prr.hec.gov.pkprr.hec.gov.pk/.../Imtiaz_Hussain_Horticulture_2015... · DECLARATION I hereby declare that contents of thesis, “Studies on the ripening aspects and fruit quality

Studies on the Ripening Aspects and Fruit Quality of Date Palm

(Phoenix dactylifera L.) Cvs. “Hillawi and Khadrawi”

By

IMTIAZ HUSSAIN

Regd. No. 2002-ag-1450

M.Sc. (Hons.) Horticulture

A thesis submitted in the partial fulfillment of the requirement for degree of

Doctor of Philosophy

in

Horticulture

Faculty of Agriculture,

UNIVERSITY OF AGRICULTURE,

FAISALABAD (PAKISTAN)

2015

DECLARATION

I hereby declare that contents of thesis, “Studies on the ripening aspects and fruit

quality of date palm (Phoenix dactylifera L.) Cvs. Hillawi and Khadrawi” are the

product of my own research and no part has been copied from any published source

(except the references, standard mathematical model/equations/formulate/protocols etc.).

I further declare that this work has not been submitted for award of any other

diploma/degree. The university may take action if the information provided is found

inaccurate at any stage (in case of any default, the scholar will be proceeded against as

per HEC plagiarism policy).

Imtiaz Hussain

(2002-ag-1450)

The Controller of Examinations,

University of Agriculture,

Faisalabad, Pakistan.

We the supervisory committee, certify that the contents and form of the thesis submitted

by Mr. Imtiaz Hussain, Reg. No. 2002-ag-1450 have been found satisfactory and

recommend that it be processed for evaluation by external examiner (s) for the award of

degree.

SUPERVISORY COMMITTEE

1. Supervisor ___________________________________

(Dr. Saeed Ahmad)

2. Member ___________________________________

(Dr. Muhammad Amjad)

3. Member ___________________________________

(Dr. Rashid Ahmad)

OPENING

HE IS THE FIRST

HE IS THE LAST HE IS THE MANIFEST

HE IS THE HIDDEN

&

HE KNOWS EVERY THING

HE BRINGS THE NIGHT INTO THE DAY

&

BRINGS THE DAY INTO THE NIGHT

&

HE KNOWS THE THOUGHTS OF THE HEARTS

S. Al-HADDID-385 (AL-QURAN)

Dedicated to

My Mother

My Father

My Sister

&

My Brothers

i

ACKNOWLEDGEMENTS

All the praises are credited to the sole creator of the entire universe ALMIGHTY

ALLAH, The Most Beneficent, The Most Merciful and The Most Compassionate, Who

granted me the power of vision and wisdom to unknot the mysteries of the universe in a

more systematic manner what people call it SCIENCE. And only by the grace of

ALLAH, I was capable to make this material contribution to already existing ocean of

knowledge. I invoke Allah’s blessings and peace for my beloved Prophet Hazrat

MOHAMMAD (Peace Be Upon Him), who is eternally present torch of direction and

knowledge for humanity as a whole and whose honorable and spiritual teachings

enlightened my heart, soul and mind.

I desire to widen most sincere thanks and deep sense of obligations to my supervisor, Dr.

Saeed Ahmad (Associate Professor) Institute of Horticultural Sciences. This manuscript

has found its way to a significant close due to his energetic supervision, and masterly

advice. I feel much happiness to utter the heartiest gratitude and sincere admiration to

Prof. Dr. Muhammad Amjad, Institute of Horticultural Sciences and Prof. Dr. Rashid

Ahmad for their generous guidance, affectionate behavior, cooperation, priceless

suggestions and moral support throughout the course of my studies.

This work was impossible without the infrastructure, facilities, and technical support

provided by “Institute of Horticultural Sciences” University of Agriculture, Faisalabad,

Pakistan, for which I am highly thankful with the core of my heart to the Director ‘Prof.

Dr. Muhammad Aslam Pervez (Late)’, faculty and staff of the Institute.

With deep sense of devotion, I wish to thank Ch. Muhammad Azhar (Director AARI)

and Mr. Abdur Rahim Khan (Research Officer), Post-harvest Research Centre Ayub

Agriculture Research Institute, Faisalabad, for his kind help and support during the

research work. I am also thankful to Pomology Lab staff (Shakil Zahid, Shakeel Latif and

M. Farhan Khalid) for their prayers and nice cooperation in lab work during the whole

period of study.

With deep sense of devotion, I wish to thank my primary education teachers (Hafiz Saif

Ullah, Ustad Mubarik, Ustad Bilal, Ustad Saeed Ahmad) for their good and valuable

initial school education, my University fellows (Dr. Waseem Ahmad, Dr. Iqbal Hussain,

Dr. Tariq Aziz, Dr. Abdul Manan, Dr. Liaqat Ali, M. Tehseen Malik, Dr. Safdar Bashir,

Dr. Adnan Bukhari, Ahmad Mustafa, Amer Farooq, M. Farooq Ahmad, M. Ishaq

Ahmad), my cousins (M. Nadir, M. Tanveer, Dr. Hassan Iqbal, M. Shakeel Tariq), my

friends (Asghar Hussain, M. Yousaf, M. Asif, M. Majeed) and all those who remember

me in their prayers.

I feel my proud privilege to mention the feelings of obligations towards my affectionate

parents, my brothers (Hafiz Khuda Bakhsh, M. Ramzan, Allah Bakhsh, M. Sajjad

Hussain, Ijaz Hussain and Fiaz Hussain), my beloved Sister, nephews and nieces for

their love, affection and prayers which enable me to acquire this long adhered aim.

I am also thankful to the Higher Education Commission, Government of Pakistan for

awarding me the financial assistance as PhD Indigenous Fellowship Programme to

achieve this goal.

Imtiaz Hussain

ii

TABLE OF CONTENTS Chapter # Title Page #

Acknowledgements i

Table of contents ii

List of tables xi

List of figures xiii

List of slides xxi

List of symbols and abbreviations xxii

Abstract 1

1 Introduction 3

2 Review of literature 7

2.1 Introduction 7

2.2 Historical milieu of date palm cultivation 7

2.3 Significance of date palm 8

2.3.1 Religious and cultural significance 9

2.3.2 Nutritional significance 9

2.3.3 Biological and curative significance 10

2.4 Nutritional composition of date fruit 11

2.4.1 Sugars composition 11

2.4.2 Phytonutritional composition 13

2.4.2.1 Antioxidants composition 13

2.4.2.2 Phenolics composition 14

2.4.2.3 Flavonoids composition 14

2.4.2.4 Polyphenols composition 14

2.5 Activity of enzymes during date fruit maturation 15

2.6 Fruits classification on the basis of ripening 16

2.6.1 Climacteric fruits 16

2.6.2 Non climacteric fruits 17

2.7 Fruit ripening mechanism 17

2.8 Date fruit maturation and development 17

2.8.1 Hababouk stage 18

2.8.2 Kimri stage 18

2.8.3 Khalal stage 18

iii

2.8.4 Rutab stage 19

2.8.5 Tamar stage 19

2.9 Monsoon rains and dates industry 22

2.10 Fruit ripening agents 22

2.10.1 Ethephon (2-chloroethyl-phosphonic acid) 22

2.10.1.1 Pre-harvest ethephon application 23

2.10.1.2 Post-harvest ethephon application 25

2.10.2 Application of NaCl and acetic acid 26

2.11 Hot water applications 27

2.12 Application of thinning practices 30

3 Material and methods 32

3.1 Experimental site description 33

3.2 Experimental material 33

3.3 Experimental details 33

3.3.1a Experiment-1a: Evaluating the potential of ethephon on

ripening acceleration and fruit quality of date palm at kimri

stage

33

3.3.1.1a Method of spray 34

3.3.1.2a Method of injection 34

3.3.1.3a Fruit harvesting 34

3.3.1.b Experiment-1b: Effectiveness of ethephon on the ripening

acceleration and physico-chemical characteristics of date

palm at khalal stage

34

3.3.1.1b Methodology 34

3.3.2 Experiment-2: Exploring the role of thinning practices on

the ripening and fruit quality of date palm

37

3.3.2.1 Method and time of thinning 37

3.3.2.2 Fruit harvesting 37

3.3.3 Experiment-3: Ripening and quality assessment of date

palm fruit by the influence of hot water treatment

39

3.3.3.1 Fruit collection and hot water treatments procedure 39

3.3.4 Experiment-4: Effects of different chemicals on the ripening

behavior and fruit quality of date palm

39

iv

3.3.4.1 Fruit collection and treatments procedure 39

3.3.5 Experiment-5: Sun-drying techniques (SDTs) affected the

fruit quality attributes of dates picked at rutab stage cv.

Hillawi.

40

3.3.5.1 Fruit collection and treatments procedure 40

3.4 Detail of field work (observations recorded) 40

3.4.1 External/physical observations recorded 40

3.4.1.1 Time taken to reach the fruit at final kimri stage (days) 40

3.4.1.2 Time taken to reach the fruit at final khalal stage (days) 40

3.4.1.3 Time taken to reach the fruit at rutab stage (days) 41

3.4.1.4 Time taken to reach the fruit at tamar stage (days) 41

3.4.1.5 Rutab fruit yield per bunch (kg) 41

3.4.1.6 Uniform fruit ripening index (%) 41

3.4.1.7 Fruit weight (g) 41

3.4.1.8 Fruit length (mm) 41

3.4.1.9 Fruit width (mm) 41

3.4.1.10 Fruit flesh weight (g) 41

3.4.1.11 Fruit stone weight (g) 41

3.4.1.12 Fruit weight loss (%) 42

3.4.2 Biochemical analysis 42

3.4.2.1 Moisture determination (%) 42

3.4.2.2 Total soluble solids concentration (oBrix) 42

3.4.2.3 Ascorbic acid (mg 100 g-1

) 42

3.4.2.4 Total titratable acidity (%) 42

3.4.2.5 Total tannin (%) 43

3.4.2.6 Total phenolics (mg GAE/100g) 43

3.4.2.7 Total antioxidants (%) 43

3.4.2.8 Total flavonoids (mg CEQ/100 ) 43

3.4.2.9 Estimation of sugars through HPLC 44

3.4.3 Organoleptic evaluation 44

3.5 Statistical analysis 45

4 Results and discussion 46

v

4.1a Study-1 Evaluating the potential of ethephon on ripening

acceleration and fruit quality of date palm at kimri stage

46

4.1.1a Results 46

4.1.1.1a Fruit maturity/ripening traits 46

4.1.1.1.1a Time taken to reach the fruit at late khalal stage (days) 46

4.1.1.1.2a Time taken to reach the fruit at rutab stage (days) 46

4.1.1.1.3a Rutab fruit yield per bunch (kg) 47

4.1.1.1.4a Uniform fruit ripening index (%) 47

4.1.1.2a Fruit physical traits 50

4.1.1.2.1a Fruit weight (g) 50

4.1.1.2.2a Fruit length (mm) 50

4.1.1.2.3a Fruit width (mm) 50

4.1.1.2.4a Fruit flesh weight (g) 50

4.1.1.2.5a Fruit pit weight (g) 50

4.1.1.3a Fruit biochemical traits 53

4.1.1.3.1a Fruit moisture content (%) 53

4.1.1.3.2a Total soluble solids concentration (oBrix) 53

4.1.1.3.3a Total titratable acidity (%) 54

4.1.1.3.4a Ascorbic acid (mg 100 g-1

) 54

4.1.1.3.5a Glucose (%) 57

4.1.1.3.6a Fructose (%) 57

4.1.1.3.7a Sucrose (%) 57

4.1.1.3.8a Reducing sugars (%) 58

4.1.1.3.9a Total sugars (%) 58

4.1.1.4a Fruit phytonutritional traits 61

4.1.1.4.1a Total phenolics (mg GAE1/00 g) 61

4.1.1.4.2a Total flavonoids (mg CEQ/100 g) 61

4.1.1.4.3a Total tannins (%) 62

4.1.1.4.4a Total antioxidants (%) 62

4.1b Study-1 Effectiveness of ethephon on the ripening

acceleration and physico-chemical characteristics of date

palm at khalal stage

65

vi

4.1.1b Results 65

4.1.1.1b Fruit maturity/ripening traits 65

4.1.1.1.1b Time taken to reach the fruit at late khalal stage (days) 65

4.1.1.1.2b Time taken to reach the fruit at rutab stage (days) 65

4.1.1.1.3b Rutab fruit yield per bunch (kg) 66

4.1.1.1.4b Uniform fruit ripening index (%) 66

4.1.1.2b Fruit physical traits 69

4.1.1.2.1b Fruit weight (g) 69

4.1.1.2.2b Fruit length (mm) 69

4.1.1.2.3b Fruit width (mm) 69

4.1.1.2.4b Fruit flesh weight (g) 69

4.1.1.2.5b Fruit pit weight (g) 69

4.1.1.3b Fruit biochemical traits 72

4.1.1.3.1b Fruit moisture content (%) 72

4.1.1.3.2b Total soluble solids concentration (oBrix) 72

4.1.1.3.3b Total titratable acidity (%) 73

4.1.1.3.4b Ascorbic acid (mg 100 g-1

) 73

4.1.1.3.5b Glucose (%) 76

4.1.1.3.6b Fructose (%) 76

4.1.1.3.7b Sucrose (%) 76

4.1.1.3.8b Reducing sugars (%) 76

4.1.1.3.9b Total sugars (%) 76

4.1.1.4b Fruit phytonutritional traits 79

4.1.1.4.1b Total phenolics (mg GAE1/00 g) 79

4.1.1.4.2b Total flavonoids (mg CEQ/100 g) 80

4.1.1.4.3b Total tannins (%) 80

4.1.1.4.4b Total antioxidants (%) 80

4.1.2 (a, b) Discussion 83

4.1.3 (a, b) Conclusion 88

4.2 Study-2 Exploring the role of thinning practices on the

ripening acceleration and fruit quality of date palm

89

4.2.1 Results 89

vii

4.2.1.1 Fruit maturity/ripening traits 89

4.2.1.1.1 Time taken from early kimri to final kimri stage (days) 89

4.2.1.1.2 Time taken from early kimri to late khalal stage (days) 89

4.2.1.1.3 Time taken from early kimri to rutab stage (days) 90

4.2.1.1.4 Rutab fruit yield per bunch (kg) 90

4.2.1.1.5 Uniform fruit ripening index (%) 91

4.2.2.1 Fruit physical traits 94

4.2.2.1.1 Fruit weight (g) 94

4.2.2.1.2 Fruit length (mm) 94

4.2.2.1.3 Fruit width (mm) 94

4.2.2.1.4 Fruit flesh weight (g) 95

4.2.2.1.5 Fruit pit weight (g) 95

4.2.3.1 Fruit biochemical traits 98

4.2.3.1.1 Fruit moisture content (%) 98

4.2.3.1.2 Total soluble solids concentration (oBrix) 98

4.2.3.1.3 Total titratable acidity (%) 99

4.2.3.1.4 Ascorbic acid (mg 100 g-1

) 99

4.2.3.1.5 Glucose (%) 102

4.2.3.1.6 Fructose (%) 102

4.2.3.1.7 Sucrose (%) 103

4.2.3.1.8 Reducing sugars (%) 103

4.2.3.1.9 Total sugars (%) 104

4.2.4.1 Fruit phytonutritional traits 107

4.2.4.1.1 Total phenolics (mg GAE1/00 g) 107

4.2.4.1.2 Total flavonoids (mg CEQ/100 g) 107

4.2.4.1.3 Total tannins (%) 107

4.2.4.1.4 Total antioxidants (%) 108

4.2.2 Discussion 111

4.2.3 Conclusion 114

4.3 Study-3 Ripening and quality assessment of date palm fruit

by the influence of hot water treatment

115

4.3.1 Results 115

viii

4.3.1.1 Fruit physical traits 115

4.3.1.1.1 Time taken to reach the fruit at tamar stage (days) 115

4.3.1.1.2 Uniform fruit ripening index (%) 115

4.3.1.1.3 Fruit weight loss (%) 116

4.3.1.1.4 Fruit moisture content (%) 116

4.3.1.1.5 Fruit flesh weight (g) 116

4.3.1.1.6 Fruit pit weight (g) 117

4.3.1.2 Fruit biochemical traits 123

4.3.1.2.1 Total soluble solids concentration (oBrix) 123

4.3.1.2.2 Total titratable acidity (%) 123


) 124

4.3.1.2.4 Glucose (%) 126

4.3.1.2.5 Fructose (%) 126

4.3.1.2.6 Sucrose (%) 127

4.3.1.2.7 Reducing sugars (%) 127

4.3.1.2.8 Total sugars (%) 128

4.3.1.3 Fruit phytonutritional traits 131

4.3.1.3.1 Total phenolics (mg GAE1/00 g) 131

4.3.1.3.2 Total flavonoids (mg CEQ/100 g) 131

4.3.1.3.3 Total tannins (%) 131

4.3.1.3.4 Total antioxidants (%) 132

4.3.1.4 Organoleptic evaluation 135

4.3.1.4.1 Color score 135

4.3.1.4.2 Taste score 135

4.3.1.4.3 Texture score 135

4.3.1.4.4 Firmness score 136

4.3.1.4.5 Astringency score 136

4.3.1.4.6 Overall acceptability score 137

4.3.2 Study-3 Effects of different chemicals on the ripening

behavior and fruit quality of date palm

141

4.3.2.1 Results 141

4.3.2.1.1 Fruit physical traits 141

ix

4.3.2.1.1.1 Uniform fruit ripening index (%) 141

4.3.2.1.1.2 Fruit weight loss (%) 141

4.3.2.1.1.3 Fruit moisture content (%) 142

4.3.2.1.1.4 Fruit flesh weight (g) 142

4.3.2.1.1.5 Fruit pit weight (g) 142

4.3.2.2.1 Fruit biochemical traits 145

4.3.2.2.1.1 Total soluble solids concentration (oBrix) 145

4.3.2.2.1.1 Total titratable acidity (%) 145

4.3.2.2.1.3 Ascorbic acid (mg 100 g-1

) 146

4.3.2.2.1.4 Glucose (%) 148

4.3.2.2.1.5 Fructose (%) 148

4.3.2.2.1.6 Sucrose (%) 149

4.3.2.2.1.7 Reducing sugars (%) 149

4.3.2.2.1.8 Total sugars (%) 150

4.3.2.3.1 Fruit phytonutritional traits 153

4.3.2.3.1.1 Total phenolics (mg GAE1/00 g) 153

4.3.2.3.1.2 Total flavonoids (mg CEQ/100 g) 153

4.3.2.3.1.3 Total tannins (%) 153

4.3.2.3.1.4 Total antioxidants (%) 154

4.3.2.4.1 Organoleptic evaluation 156

4.3.2.4.1.1 Color score 156

4.3.2.4.1.2 Taste score 156

4.3.2.4.1.3 Texture score 157

4.3.2.4.1.4 Firmness score 157

4.3.2.4.1.5 Astringency score 157

4.3.2.4.1.6 Overall acceptability score 158

4.3.2 (1, 2) Discussion 162

4.3.3 (1, 2) Conclusion 167

4.4 Study-4 Sun-drying techniques (SDTs) affected the fruit

quality attributes of dates picked at rutab stage cv. Hillawi

168

4.4.1 Results 168

4.4.1.1 Fruit weight loss (%) 168

x

4.4.1.2 Fruit moisture content (%) 168

4.4.1.3 Total soluble solids concentration (oBrix) 168

4.4.1.4 Total titratable acidity (%) 169

4.4.1.5 Reducing sugars (%) 169

4.4.1.6 Total sugars (%) 169

4.4.1.7 Total phenolics (mg GAE/100 g) 173

4.4.1.8 Total flavonoids (mg CEQ/100 g) 173

4.4.1.9 Total antioxidants (%) 173

4.4.1.10 Total tannins (%) 173

4.4.2 Discussion 176

4.4.3 Conclusion 178

5 General discussion: Conclusions: Recommendations 181

5.1 General discussion 181

5.2 Conclusions 186

5.3 Recommendations 186

4.5 Future research needed 187

LITERATURE CITED 188

xi

LIST OF TABLES Table # Title Page #

3.1 Organoleptic evaluation of Hillawi and Khadrawi date palm

cultivars.

45

4.1 Effects of different strands thinning intensities on time taken

(days) from early kimri to late kimri stage of Hillawi and

Khadrawi date palm fruit.

91


(days) from early kimri to late khalal stage of Hillawi and

Khadrawi date palm fruit.

91


(days) from early kimri to rutab stage of Hillawi and Khadrawi

date palm fruit.

91

4.4 Effects of different strands thinning intensities on rutab fruit

yield (kg) per bunch of Hillawi and Khadrawi date palm fruit.

93

4.5 Effects of different strands thinning intensities on uniform fruit

ripening index (%) of Hillawi and Khadrawi date palm fruit.

93

4.6 Effects of different strands thinning intensities on individual fruit

weight (g) of Hillawi and Khadrawi date palm fruit.

96

4.7 Effects of different strands thinning intensities on fruit length

(mm) of Hillawi and Khadrawi date palm fruit.

96

4.8 Effects of different strands thinning intensities on fruit width

(mm) of Hillawi and Khadrawi date palm fruit.

97

4.9 Effects of different strands thinning intensities on fruit flesh


97

4.10 Effects of different strands thinning intensities on fruit pit weight

(g) of Hillawi and Khadrawi date palm fruit.

98

4.11 Effects of different strands thinning intensities on fruit moisture

content (%) of Hillawi and Khadrawi date palm fruit.

100

4.12 Effects of different strands thinning intensities on total soluble

solids concentration (oBrix) of Hillawi and Khadrawi date palm

fruit.

101

4.13 Effects of different strands thinning intensities on titratable 101

xii

acidity (%) of Hillawi and Khadrawi date palm fruit.

4.14 Effects of different strands thinning intensities on ascorbic acid

(mg 100 g-1

) of Hillawi and Khadrawi date palm fruit.

102

4.15 Effects of different strands thinning intensities on glucose (%) of

Hillawi and Khadrawi date palm fruit.

104

4.16 Effects of different strands thinning intensities on fructose (%) of


105

4.17 Effects of different strands thinning intensities on sucrose (%) of


105

4.18 Effects of different strands thinning intensities on reducing

sugars (%) of Hillawi and Khadrawi date palm fruit.

106

4.19 Effects of different strands thinning intensities on total sugars

(%) of Hillawi and Khadrawi date palm fruit.

106

4.20 Effects of different strands thinning intensities on total phenolics

(mg GAE/100 g) of Hillawi and Khadrawi date palm fruit.

109

4.21 Effects of different strands thinning intensities on total

flavonoids (mg CEQ/100 g) of Hillawi and Khadrawi date palm

fruit.

109

4.22 Effects of different strands thinning intensities on total tannins


110

4.23 Effects of different strands thinning intensities on total

antioxidants (%) of Hillawi and Khadrawi date palm fruit.

110

xiii

LIST OF FIGURES Figure # Title Page #

3.1 Average meteorological data during two seasons (2011-2012) at

experimental site of date palm orchard.

45

4.1a Effects of different ethephon concentrations (spray and injection)

on time taken (days) from final kimri to late khalal stage of

Hillawi and Khadrawi date palm fruit ± S.E.

48


on time taken (days) from final kimri to rutab stage of Hillawi

and Khadrawi date palm fruit ± S.E.

48


on rutab fruit yield per bunch (kg) of Hillawi and Khadrawi date

palm fruit ± S.E.

49


on uniform fruit ripening index (%) of Hillawi and Khadrawi

date palm fruit ± S.E.

49


on fruit weight (g) of Hillawi and Khadrawi date palm ± S.E.

51


on fruit length (mm) of Hillawi and Khadrawi date palm ± S.E.

51


on fruit width (mm) of Hillawi and Khadrawi date palm ± S.E.

52


on flesh weight (g) of Hillawi and Khadrawi date palm fruit ±

S.E.

52


on pit weight (g) of Hillawi and Khadrawi date palm fruit ± S.E.

53


on fruit moisture content (%) of Hillawi and Khadrawi date palm

fruit ± S.E.

55


on total soluble solids concentration (oBrix) of Hillawi and

Khadrawi date palm fruit ± S.E.

55

xiv


on titratable acidity (%) of Hillawi and Khadrawi date palm fruit

± S.E.

56


on ascorbic acid (mg 100 g-1

) of Hillawi and Khadrawi date palm

fruit ± S.E.

56


on glucose (%) of Hillawi and Khadrawi date palm fruit ± S.E.

59


on fructose (%) of Hillawi and Khadrawi date palm fruit ± S.E.

59


on sucrose (%) of Hillawi and Khadrawi date palm fruit ± S.E.

60


on reducing sugar (%) of Hillawi and Khadrawi date palm fruit ±

S.E.

60


on total sugars (%) of Hillawi and Khadrawi date palm fruit ±

S.E.

61


on total phenolics (mg GAE/100 g) of Hillawi and Khadrawi date

palm fruit ± S.E.

63


on total flavonoids (mg CEQ/100 g) of Hillawi and Khadrawi


63


on total tannins (%) of Hillawi and Khadrawi date palm fruit ±

S.E.

64


on total antioxidants (%) of Hillawi and Khadrawi date palm

fruits ± S.E.

64

4.23b Effects of different ethephon concentrations (spray and injection)

on time taken (days) from early khalal to late khalal stage of


67

xv


on time taken (days) from early khalal to rutab stage of Hillawi


67



palm fruit ± S.E.

68


on uniform fruit ripening index (%) of Hillawi and Khadrawi


68


on individual fruit weight (g) of Hillawi and Khadrawi date palm

± S.E.

70



70



71


on flesh weight (g) of Hillawi and Khadrawi date palm fruit ±

S.E.

71



72


on moisture content (%) of Hillawi and Khadrawi date palm fruit

± S.E.

74




74


on total titratable acidity (%) of Hillawi and Khadrawi date palm

fruit ± S.E.

75




fruit ± S.E.

75

xvi



77



77



78


on reducing sugars (%) of Hillawi and Khadrawi date palm fruit

± S.E.

78


on total sugars (%) of Hillawi and Khadrawi date palm fruit ±

S.E.

79



palm fruit ± S.E.

81


on total flavonoids (mg CEQ/100 g) of Hillawi and Khadrawi


81


on total tannins (%) of Hillawi and Khadrawi date palm fruit ±

S.E.

82


on total antioxidants (%) of Hillawi and Khadrawi date palm fruit

± S.E.

82

4.45 Effects of hot water treatments at 65oC on time taken to tamar

stage (days) of Hillawi and Khadrawi date palm fruit ± S.E.

118

4.46 Effects of hot water treatments at 65oC on uniform fruit ripening

index (%) of Hillawi and Khadrawi date palm fruit ± S.E.

118

4.47 Effects of hot water treatments at 65oC on fruit weight loss (%)

of Hillawi and Khadrawi date palm fruit ± S.E.

119

4.48 Effects of hot water treatments at 65oC on moisture content (%)


119

4.49 Effects of hot water treatments at 65oC on flesh weight (%) of 120

xvii


4.50 Effects of hot water treatments at 65oC on pit weight (%) of


120

4.51 Effects of hot water treatments at 65oC on total soluble solids

concentration (oBrix) of Hillawi and Khadrawi date palm fruit ±

S.E.

124

4.52 Effects of hot water treatments at 65oC on titratable acidity (%)


125

4.53 Effects of hot water treatments at 65oC on ascorbic acid (mg 100

g-1

) of Hillawi and Khadrawi date palm fruit ± S.E.

125

4.54 Effects of hot water treatments at 65oC on glucose (%) of Hillawi


128

4.55 Effects of hot water treatments at 65oC on fructose (%) of


129

4.56 Effects of hot water treatments at 65oC on sucrose (%) of Hillawi


129

4.57 Effects of hot water treatments at 65oC on reducing sugars (%) of


130

4.58 Effects of hot water treatments at 65oC on total sugars (%) of


130

4.59 Effects of hot water treatments at 65oC on total phenolics (mg

GAE/100 g) of Hillawi and Khadrawi date palm fruit ± S.E.

133

4.60 Effects of hot water treatments at 65oC on total flavonoids (mg

CEQ/100 g) of Hillawi and Khadrawi date palm fruit ± S.E.

133

4.61 Effects of hot water treatments at 65oC on total tannins (%) of


134

4.62 Effects of hot water treatments at 65oC on total antioxidants (%)


134

4.63 Effects of hot water treatments at 65oC on color score of Hillawi


138

4.64 Effects of hot water treatments at 65oC on taste score of Hillawi


138

4.65 Effects of hot water treatments at 65oC on texture score of 139

xviii


4.66 Effects of hot water treatments at 65oC on firmness score of


139

4.67 Effects of hot water treatments at 65oC on astringency score of


140

4.68 Effects of hot water treatments at 65oC on overall acceptability

score of Hillawi and Khadrawi date palm fruit ± S.E.

140

4.69 Effects of different chemicals on uniform fruit ripening index

(%) of Hillawi and Khadrawi date palm fruit after incubation at

40±1oC for 72 h ± S.E.

143

4.70 Effects of different chemicals on fruit weight loss (%) of Hillawi

and Khadrawi date palm fruit after incubation at 40±1oC for 72 h

± S.E.

143

4.71 Effects of different chemicals on fruit moisture content (%) of

Hillawi and Khadrawi date palm fruit after incubation at 40±1oC

for 72 h ± S.E.

144

4.72 Effects of different chemicals on fruit flesh weight (g) of Hillawi


± S.E.

144

4.73 Effects of different chemicals on fruit pit weight (g) of Hillawi


± S.E.

145

4.74 Effects of different chemicals on total soluble solids

concentration (oBrix) of Hillawi and Khadrawi date palm fruit

after incubation at 40±1oC for 72 h ± S.E.

147

4.75 Effects of different chemicals on titratable acidity (%) of Hillawi


± S.E.

147

4.76 Effects of different chemicals on ascorbic acid (mg 100 g-1

) of


for 72 h ± S.E.

148

4.77 Effects of different chemicals on glucose (%) of Hillawi and

Khadrawi date palm fruit after incubation at 40±1oC for 72 h ±

150

xix

S.E.

4.78 Effects of different chemicals on fructose (%) of Hillawi and


S.E.

151

4.79 Effects of different chemicals on sucrose (%) of Hillawi and


S.E.

151

4.80 Effects of different chemicals on reducing sugars (%) of Hillawi


± S.E.

152

4.81 Effects of different chemicals on total sugars (%) of Hillawi and


S.E.

152

4.82 Effects of different chemicals on total phenolics (mg GAE/100 g)

of Hillawi and Khadrawi date palm fruit after incubation at

40±1oC for 72 h ± S.E.

154

4.83 Effects of different chemicals on total flavonoids (mg CEQ/100

g) of Hillawi and Khadrawi date palm fruit after incubation at

40±1oC for 72 h ± S.E.

155

4.84 Effects of different chemicals on total tannins (%) of Hillawi and


S.E.

155

4.85 Effects of different chemicals on total antioxidants (%) of


for 72 h ± S.E.

156

4.86 Effects of different chemicals on color score after incubation at

40±1oC for 72 h ± S.E.

158

4.87 Effects of different chemicals on taste score after incubation at

40±1oC for 72 h ± S.E.

159

4.88 Effects of different chemicals on texture score after incubation at

40±1oC for 72 h ± S.E.

159

4.89 Effects of different chemicals on firmness score after incubation

at 40±1oC for 72 h ± S.E.

160

xx

4.90 Effects of different chemicals on astringency score after

incubation at 40±1oC for 72 h ± S.E.

160

4.91 Effects of different chemicals on overall acceptability score after

incubation at 40±1oC for 72 h ± S.E.

161

4.92 Effects of sun-drying techniques on weight loss (%) in the fruits

of Hillawi cultivar analyzed at tamar stage ± S.E.

170

4.93 Effects of sun-drying techniques on moisture content (%) in the

fruits of Hillawi cultivar analyzed at tamar stage ± S.E.

170

4.94 Effects of sun-drying techniques on total soluble solids

concentration (%) in the fruits of Hillawi cultivar analyzed at

tamar stage ± S.E.

171

4.95 Effects of sun-drying techniques on total titratable acidity (%) in

the fruits of Hillawi cultivar analyzed at tamar stage ± S.E.

171

4.96 Effects of sun-drying techniques on reducing sugars (%) in the


172

4.97 Effects of sun-drying techniques on total sugars (%) in the fruits


172

4.98 Effects of sun-drying techniques on total phenolics (mg

GAE/100 g) in the fruits of Hillawi cultivar analyzed at tamar

stage ± S.E.

174

4.99 Effects of sun-drying techniques on total flavonoids (mg

CEQ/100 g) in the fruits of Hillawi cultivar analyzed at tamar

stage ± S.E.

174

4.100 Effects of sun-drying techniques on total antioxidants (%) in the


175

4.101 Effects of sun-drying techniques on total tannins (%) in the fruits


175

xxi

LIST OF SLIDES Slide # Title Page #

2.1 Different edible stages of Khadrawi fruit. 20

2.2 Different edible stages of Hillawi fruit. 21

3.1 Mature fruit of date palm at final kimri stage cv. Hillawi. 32

3.2 Mature fruit of date palm at final kimri stage cv. Khadrawi. 32

3.3 Application of ethephon by foliar spray and injection. 35

3.4 Performing strands thinning practices at early kimri stage. 38

4.1 Effects of hot water treatment (HWT) on the ripening behavior of

Hillawi fruit under ambient conditions.

121

4.2 Effects of hot water treatment (HWT) on the ripening behavior of

Khadrawi fruit under ambient conditions.

122

4.3 Different steps involved in the processing of soft Hillawi dates

by modified sun-drying techniques.

179

xxii

LIST OF SYMBOLS AND ABBREVIATIONS Abbreviation Description

@ At the rate of o Degree

% Percent

µL Microliter (s)

$ United States Dollar

A Absorbance

≤ Less than or equal to

≥ Greater than or equal to

± Plus minus

AA Abscisic acid

AARI Ayub Agricultural Research Institute

ASF Agri. Support Fund

C2H2 Ethylene

Ca Calcium

Ca+2

Calcium ions

CEQ Catechin equivalents

cm Centimeter

CRD Completely randomized design

cv Cultivar (s)

DDH2O Double distilled water

DF Date fruit

DMRT Duncan’s Multiple Range Test

DPPH 2, 2, diphenyl-1-picrylhydrazyl

ELISA Enzyme-linked immunosorbent assay

et al. et alia

FAO Food and Agriculture Organization

FC Folin-Ciocalteu

Fe Iron

g Gram (s)

GAE Gallic acid equillents

GOP Government of Pakistan

h Hour

ha Hectare

HPLC High Performance Liquid Chromatograph

HW Hot water

HWD Hot water dipping

I Inhibition

i.e. Illud est

IC Inhibition concentration

IHS Institute of Horticultural Sciences

K Potassium

kg Kilogram

KPK Khyber Pakhtunkhaw

L Liter

L-1

Per liter

LC Liquid chromatography

xxiii

LSD Least significant difference

M Molarity

m/v Mass over volume

Mg Magnesium

mg Milligram

min Minute

ml Milliliter

mm Millimeter

mM Millimolar

Mt. Metric ton

N Normality

Na2CO3 Sodium carbonate

NaCl Sodium chloride

NaHCO3 Sodium bicarbonate

NaOH Sodium hydroxide

nm Nano-meter

ns Non-significant oC Degree Celsius

P Probability

PARS Post Graduate Agricultural Research Station

PE Pectin esterase

PG Polygalacturonase

PL Pectate lyases

ppm Parts per million

R.H Relative humidity

RCBD Randomized complete block design

RCS Removal of central strands

ReID Refractive index detector

S.E Standard error

SBI Sindh Board of Investment

SDT Sun-drying technique

SL Soluble liquid

SSC Soluble solids concentrate

STT Shortening of terminal tips

TA Total titratable acidity

TFC Total flavonoids contents

TPC Total phenolic contents

TSS Total soluble solids

UV Ultra violet

v/v Volume/volume

viz. Videlicet

vs. Versus

1

ABSTRACT

Date palm is an important fruit crop in the world as well as in Pakistan. It provides a rich

and quick energy source to humans and also plays a significant role in the social and

economic life of the people living in dry areas. Monsoon rains at the time of fruit

harvesting or ripening are very harmful and heavy fruit losses occur resulting rotting, fruit

drop and uneven fruit ripening. Unfortunately, in Pakistan serious losses occur due to

these rains at the time of fruit harvesting/ripening. The research work reported in this

manuscript was conducted in the Experimental Fruit Orchard Square Number 9 and Post

Graduate Agricultural Research Station (PARS) (Latitude 31o-26´ N, Longitude 73

o-06´ E

and Altitude 184.4 m), Institute of Horticultural Sciences, University of Agriculture

Faisalabad, Punjab Province, Pakistan. In the field studies, effectiveness of ethephon

application (foliar and injection) and strands thinning practices on ripening acceleration

and fruit quality of date palm were investigated and found that ethephon application with

spray showed superiority over injection method to accelerate the maturity and ripening

processes of date fruits in both Hillawi and Khadrawi cultivars. Fruit sprayed with

ethephon (4 ml/L and 2 ml/L) at final kimri and early khalal stages reached at rutab stage

13 and 6 days earlier and showed uniform fruit ripening indexes of 60.46 and 44.85% and

rutab fruit yield (6.29 and 4.37 kg ) per bunch with good fruit quality composition than

the untreated fruits. Second field experiment was conducted to explore the role of strands

thinning on maturity enhancement and fruit quality. Strands thinning practices were

carried out with following intensities (no thinning, 20% RCS (removal of central strands),

30% RCS, 20% STT (shortening of terminal tips), 30% STT, 20% RCS + 20% STT and

30% RCS + 30% STT) at early kimri stage (4 weeks after pollination). It was observed

that strands thinning practices improved quality characteristics than the fruit those were

untreated (without thinning) in both cultivars. Strands thinning intensity @ 30% RCS

alone resulted in 10 days earlier maturity and higher rutab yield of 5.22 kg per bunch and

more uniformly ripe fruit (76.28%) at rutab stage. The total soluble solids, ascorbic acid,

sugars (glucose, fructose and sucrose), total phenolic, total flavonoids and total

antioxidants were significantly improved while titratable acidity and total tannin contents

were decreased in thinned fruits. In post-harvest experiments, hot water exposures for 3

and 5 min at 65oC in Hillawi and Khadrawi cultivars reduce the fruit ripening period up to

6 days and produced uniformly ripened fruit (73.33 and 81.66%) with better quality and

higher acceptability of organoleptic scores marked by the panellists as compared to

2

untreated fruit. Acetic acid @ 3% showed higher uniform ripening index of 64.24% with

higher total soluble solids, sugars, total phenolic, total flavonoids, total antioxidants and

organoleptic properties after incubation at 40±1oC for 72 h. In the last study different sun

drying techniques were used for the curing of soft Hillawi dates. Among different sun-

drying techniques, SDT4 (DSE with removal in baskets and covered during night) proved

good regarding the fruit quality composition such as TSS, acidity, total sugar, reducing

sugar, total phenolics, total antioxidants, total flavonoids with lower amounts of total

tannin contents. In conclusion, a spray application of ethephon @ 4 ml/L at final kimri

stage, strands thinning @ 30% RCS alone at early kimri stage, hot water treatments at

khalal stage (3 min for Hillawi and 5 min for Khadrawi) and acetic acid @ 3% at khalal

stage showed better results to accelerate the fruit ripening period and produced higher

index of uniformly ripe fruits with good fruit quality composition in both date palm

cultivars. Among different sun-drying techniques in fruits harvested at rutab stage, SDT4

(DSE with removal in baskets and covered during night) proved good regarding the fruit

quality composition in Hillawi date palm cultivar. Uniformity in ripening gave extra

benefits and higher economic returns were achieved by adopting these technologies and it

provided higher economic return.

3

Chapter-1 INTRODUCTION

Date palm (Phoenix dactylifera L.) is a primeval plant and considered as a ‘symbol of

life’ in the desert oases of Arab world countries for centuries (Baliga et al., 2011). It is

monocotyledonous, dioecious in nature and belongs to family Palmaceae (Barrow, 1998).

Date palm has 14 recognized species; dactylifera is one of the most cultivated fruit crop

in world. Dactylifera is widely spread in the tropical and subtropical regions of Africa

and southern Asia with varied geographical, soil and climatic conditions (El-Hadrami et

al., 2011). The name of date palm originates from its fruit ‘Phoenix’ which means purple

or red in Greek and ‘dactylifera’ refers due to the finger like appearance of fruit bunches.

The morphology of male and female date palm plants varies according to the structure of

inflorescence. The flowers of both male and female are covered in a hard, fibrous sheath

that protects them from heat and sunlight at early growth stages during flower initiation or

development (Nixon and Carpenter, 1978; Vandercook et al., 1980).

Globally, date palm is grown in 37 countries with more than 2000 different cultivars (Ali-

Mohamed and Khamis, 2004). A large population of date palm trees is found in the

Arabian Gulf and North Africa with a small population in North American states

(California, Arizona and Mexico). Date palm requires high temperature of 35oC for

optimum pollen development, fruit set and ripening with low relative humidity. It requires

abundance of water drained from bottom of the soil or from surface irrigation through a

deep-rooted structure. The date palm grows well in almost less rain fall areas at North

latitude ranging from 9-39o with areas represented by Sahara desert in Africa and

Southern borders of Near East commonly known as Arabian Peninsula, Southern Iraq and

Jordan. A date palm garden can survive up to an average life of 40-50 years, but few are

still productive up to 150 years (Chao and Krueger, 2007).

Presently, global production, consumption and industrialization of date palm are

increasing constantly as noticed in main date palm producing states such as Egypt (1.37

million tons), Saudi Arabia (1.12 million tons), Iran (1.01 million tons), UAE (0.900

million tons), Algeria (0.690 million tons), Iraq (0.619 million tons) and Pakistan (0.557

million tons) (FAOSTAT, 2011). World area under date palm cultivation in 2009-10 was

1.3 million hectares (FAOSTAT, 2011). However, the area under cultivation had been

increased by 0.300 million ha during the last few decades. Gulf countries are the biggest

producer of dates having an area under cultivation of 0.833 million hectares followed by

4

Africa (0.416 million hectares) and North Africa (0.392 million hectares). In American

states and European Union, the date’s production holds just a few thousand hectares.

While, Middle East and North Africa are the main dates producing centers with an annual

production of 2.70 million tons. United States is at top rank regarding dates annual

production with an average of 67.09 tons ha-1

followed by North African countries on an

average of 64.97 tons ha-1

. Although a large number of production groves exist in the

Middle East but annual production is below the world average of 53.79 tons ha-1

(FAOSTAT, 2011). The Middle-East and North African countries account for almost

60% of total world’s production with the cultivation of about 800 cultivars (Mikki, 1998).

Pakistan ranks seventh in world dates production with an annual production of 0.557

million tons on an area of 90.10 thousand hectares, contributing 10% share in global

production (GOP, 2011). Date palm is third major fruit crop of the country having more

than 325 well known cultivars (Jamil et al., 2010). These cultivars are distinctive in their

flavor and texture and are extremely practicable for commercial production and

successful cultivation in all over the country. Sindh (50-52%) and Baluchistan (38%) are

the major date producers and contributes 85-90% share in total production of country.

While Punjab and Khyber Pakhtunkhwah (KPK) contributes 10% and 3-4%, respectively.

In Baluchistan, the prime cultivated varieties are Mozawati, Begum Jangi, Kaharba,

Sabzo, Halini, Gongna, Jansor, Dashtiari, Aseel, while in Sindh, Aseel, Fasli, Bhedir,

Karbalian, Kurpo and Red Zardi are the main focusing varieties. Hillawi, Khadrawi,

Zahidi and Dorn are grown in Punjab whereas in KPK the major cultivated varieties are

Dhakki, Mozawati, Basrai, Kango, Halini, Zahidi, Gulistan and Shakri. During the year

2010-2011, Pakistan’s dates export was $48.211 million in both fresh and dried forms.

India is the major importer of dried dates of 91.47 thousand tons while other importing

countries are Australia, Bangladesh, Canada, Denmark, Germany, Malaysia, New

Zealand, Japan, Turkey, Qatar, South Africa and United Kingdom (SBI, 2010).

Date palm has a unique significance over other fruits due to historical cultivation, multi-

nutrition, consumption and use of every plant part (Barreveld, 1993). Date fruit is highly

nutritious and an important source of sugars (glucose, fructose and sucrose), fibers,

mineral elements, vitamins, minute amount of fats and proteins (Mohamed, 2000; Al-

Farsi et al., 2005; Baloch et al., 2006). Muslims widely consume dates it in the Holy

month of ‘Ramzan’ at ‘Iftar’ time as it provides a quick source of energy. Therefore,

dates are considered as an ideal food with abundant of potential health benefits

(Barreveld, 1993; Al-Shahib et al., 2003; Al-Farsi et al., 2005; Elleuch et al., 2008).

5

Dates also contain K and little quantity of Na contents which are fit for hypertensive

individuals (Al-Hooti et al., 2002). The fruit of date palm is also considered for

antimutagenic and anticancer patients (Ishurd and Kennedy, 2005). Mostly dates are

consumed in two forms; fresh or dried. But date fruit is also consumed in different ways

like; fresh table dates, frozen dates (rutab), dates filled with nuts, chocolate coverings and

mixed with seeds of sesame seeds and numerous other such types of forms.

Climate is one of the main factor affecting dates cultivation and production. In Pakistan,

the peak production period of dates begins in hot months of July and August. Monsoon

rain during these months is a real threat for date fruit crop, because at the time of fruit

ripening, monsoon rains even for very short duration can damage up to 60% date crop

(ASF, 2010). ‘Hillawi’ and ‘Khadrawi’ are the main cultured varieties of Punjab and are

totally consumed at khalal stage. There is no concept among the date growers to process

these varieties because of monsoon rains and they harvest the fruit at khalal stage. At this

stage 50-60% fruit remains immature with poor quality and sold it at lower prices in the

market. Both these varieties are soft in texture and their ripening period starts from mid-

July to August. Monsoon rains affects these varieties badly. About 60% date fruit crop is

damaged due to these rains with uneven ripening, poor fruit quality and fruit drop. In

several cases, this harm may go up to 100% loss of the date fruit crop (SBI, 2010). Thus,

to overcome these heavy losses, there is a need to force early ripening on or even off the

tree with uniform and good quality fruit.

Fruit ripening is an irreversible phenomenon which involves different physical,

biochemical and organoleptic changes. These changes are interdependent on each other.

After successful completion of these changes fruit become edible with desirable quality

(Prasanna et al., 2007). Exogenous applications of some chemicals can accelerate the

ripening process through increased respiration, starch hydrolysis, softening, flavor and

colour. The different ripening agents such as calcium carbide, acetylene, ethylene,

propylene, ethephon (2-chloroethyl phosphonic acid), glycol and ethanol are commonly

used for the ripening of fruits and vegetables (Asif, 2012). Ethephon is potentially used to

ripen the fruit before and after harvest (Cua and Lizada, 1990; Padmini and Prabha, 1997;

Singh and Janes, 2001). Ethephon once applied, penetrates into the fruit tissues and

decomposes the ethylene as it is an ethylene generating compound. Ethylene hydrolyzes

in plant tissues and initiates the ripening in climacteric fruits (Warner and Leopold, 1967;

Cooke and Randall, 1968). Post-harvest application of various other chemicals such as

sodium hydroxide, sodium chloride and acetic acid also accelerates the fruit ripening in

6

date palm (Shamshiri and Rahemi, 1999). These have a profound effect on the maturity

and ripening by advancing or delaying the fruit harvesting period (Looney, 1998).

Moreover, heat affects the fruit ripening processes in different ways which includes

change in color (Tian et al., 1996; Cheng et al., 1988), synthesis of ethylene (Ketsa et al.,

1998), respiration (Inaba and Chachin, 1988), firmness, break down of cell wall

components (Lurie and Nussinovich, 1996) and accumulation of different volatile

compounds with enhanced fruit ripening rate (McDonald et al., 1999). Thinning is also

considered as an important managerial approach in date palm to improve the fruit size,

fruit weight, fruit quality, reduces the chances of bunch breaking, and alternate bearing

(Ibrahim and Kashif, 1998; Alkhateeb and Ali-Dinar, 2002; Ali-Dinar et al., 2002) and

also shorten fruit drop and hasten the fruit ripening (Zaid, 1999).

Modifications in the fruit maturation period and uniformity in ripening are much more

important in the date fruit industry for fulfilling the early or late market demands,

staggering fruit harvest and to avoid the effects of unfavorable climatic conditions. This

facilitates the single harvest of the fruits and also reduces the labor cost. In Pakistan,

research on date palm does not have promotes as compared to other major fruit crops

(citrus, mango and guava). Therefore, very little work has been reported regarding the

ripening acceleration and fruit quality of date palm with the use of different chemicals.

Present study, therefore, was carried out with the following objectives.

To find out the ways to accelerate the date palm fruit ripening on tree and after

harvest.

To produce uniform ripening and good quality fruit.

7

Chapter-2 REVIEW OF LITERATURE

2.1 Introduction

Date palm (Phoenix dactylifera L.) is successfully cultivated in the scorching areas of

Southwest Asia and North Africa (Dowson, 1982; Zaid, 1999; Al Farsi and Lee, 2008). It

grows well under hot, arid and brackish soil than any other fruit crops (Lunde, 1978). It is

the main fruit crop in arid and semi-arid regions of Western Asia and North Africa

situated between 24oN and 34

oN (Zaid and Arias-Jimenez, 2002). A proverb is very

famous about date palm that “its head exist in fire while its feet live in water”. It is one of

the oldest mankind‟s cultivated fruit plants on earth (Yousif et al., 1987). Due to its high

nutritious worth, yield and lengthy productive life span (100 years); it is also called as

“tree of life” in Bible (UN, 2003). The fruit of date palm has been used as staple food in

hot and desert areas of the planet for thousands of years and is considered as an admired

food product of these areas (Sarig et al., 1989). It is regarded as a one of the most

important socio-economic component of the people living in hot and dry areas of world.

As well as the civilization moves out from the Middle East, date palm cultivation has

been extended up to Spain and United States (Sauer, 1993).

2.2 Historical milieu of date palm cultivation

Historically, date palm has been linked with sustaining the human life and traditional

values of the people living in old world as a chief agricultural crop. In the universe, tree

of date palm is regarded as the oldest known tree from which man has derived benefits,

and it has been cultivated since ancient times (Riad, 2006). Initially, date palm cultivation

was coextensive to the ancient civilizations and then it widely spread from Africa

(northeast) to Tigris and uplands of Euphrates (Dawson, 1982). Pre-historically,

Phoenicians introduced the cultivation of date palm in Mediterranean areas. In Iran about

4000 years ago along the banks of two large rivers „Karoon‟ and „Karkheh‟ people have

been cultivating the dates. The exact origin of date palm has been lost in past and is still

unknown due to its long cultivation history, extensive distribution and swap of different

date cultivars, but most likely it is thought that Mesopotamia or Western India are the

original centers of date palm (Wrigley, 1995). Around 5000 years ago, the cultivation of

date palm was expanded to Arabian Peninsula, North Africa and Middle East states

(Kader and Hussein, 2009). In the Middle East the date palm cultivation was started

8

around 6000 BC (Al-Qarawi et al., 2003). Its domestication goes back to 3000 B.C. in

Mesopotamia which is now called as southern Iraq and might be its cultivation goes back

to at least 5000 B.C. in the Arab and North African countries (Zohary and Hopf, 2000). In

the Middle-East it has been cultivated as early as 6000 B.C. (Al-Qarawi et al., 2003). In

Indus Valley (Pakistan) archaeological excavations reported that the cultivation of date

palm goes back to 2000 B.C. In Arabian Peninsula, the date palm is regarded as an

ancient mankind‟s cultivated fruit plant, and played a vital role in the daily life for the

people of these areas for at least 7000 years (Ahmed et al., 1995). According to

archaeological indications, date palm has been cultivated in Mehrgarh (West Pakistan)

around 7000 BCE at the time of Neolithic civilization. This evidence of date‟s cultivation

is also related to the Indus Valley civilizations which includes Harappan period around

2600-1900 BCE (Kenoyer et al., 2005). During the second millennium B.C. date‟s

cultivation spread to Egypt and with the expansion of Islam, it has been brought to

southern Spain and Pakistan. Ancient thoughts reported that Spanish were the first who

introduce the dates in the Arabian Peninsula, North Africa, and the South Asia (Middle

East), then it reached to America (Nixon, 1951). Date palm cultivation was mainly spread

by soldiers during fighting missions, traders and excavators who eat dates as energy

source and throw away the pits there (Barreveld, 1993). Some researchers believe that it

is probably originated somewhere from the North African desert oases and southwest

Asia (El-Shibli and Korelainen, 2009). Date fruit has been considered as a rich energy

source and most popular food commodity in the Arabian Gulf and its neighboring

countries for thousands of years (Khatchadourian et al. 1982).

2.3 Significance of date palm

In world dry regions, date palm has been widely cultivated as an important cash crop and

playing an important role in the history of mankind since ancient times. It has a

significant role to nourish the residents of these areas due to its high nutritional value,

health, economic, spiritual, aesthetic and environmental importance. It also plays an

important role to provide an appropriate habitation for the nomad‟s in the form of shade

to avoid the hot winds of deserts. The fruit of date palm is composed of a fleshy seeded

pericarp (Besbes et al., 2004; Erskine et al., 2004). Worldwide, date fruit has its unique

nutritional significance and it is consumed as fresh or other derived by-products. The date

palm is a mainly an important produce in scorched areas and plays a significant part in

9

economic and social life of the people living in these areas (Besbes et al., 2004; Sahari et

al., 2007).

2.3.1 Religious and cultural significance

The date palm has religious values as well as cultural significance for mankind. In the

„Holy Qur‟an more than 20 verses narrated the importance of date palm than any other

fruit bearing plant, which is associated with the religion and Muslims. The name of date

palm is cited in the holy books like Qur‟an, Torah and Buddha, due to its prized value and

historic importance (Belarbi et al., 2000; Falade and Abbo, 2007). All the Muslims in

world eat few dates (3, 5 and 7) with few sips of water at Iftar time in the Holy month of

„Ramadan‟ to break their fast. It is important in ceremonies of Judaism, Christianity,

Islam and Hinduism. A large number of people used the date fruit in religious traditions

as a part of their food which they consumed with bread. For Muslims the religious

significance of date palm goes back to Prophet Ibrahim, who was living in Ur and loved

dates. All the Muslims in the world value the life of Muhammad (PBUH) and they try to

do as much as possible as He did. During the start of Islam, Muhammad (PBUH) eats

only dates and drink water for months. Hazrat Aisha (R.A) narrated that the Prophet

(PBUH) said: A home which has dates will never go starving (Sahee Muslim, 2002).

Hazrat Sa‟ad (R.A) narrates that the Prophet (PBUH) said, „Whoever awakens to eat

seven dates of „Ajwa‟ will not be harmed by poison or black magic (Saheeh Bukhaari,

2001). In Christianity, the palm leaves (fronds) are used for celebration of Easter festival

(Zohary and Hopf, 2000).

2.3.2 Nutritional significance

Date fruit is considered as an important nutritional component in the food of the residents

where it is cultivated. The fruit of date palm also becomes a vital part in daily life of the

people for those countries which import this fruit (El-Hadrami and El-Hadrami, 2009).

Date fruit is rich source of chemical constituents which are variable due to numerous

factors such as cultivar type, area of cultivation, climatic conditions, fertilizer application

and different management operations. (Al-Rawahi et al., 2005). Dates are rich source of

carbohydrates (70%), mostly are present in the form of sugars. Invert sugar is entirely

found in most of the date varieties, as it rapidly dissolved in the human body (Ahmed et

al., 1995; Al-Hooti et al., 1997; Myhara et al., 1999). Date fruit is considered as an

important energy component mainly due to the presence of higher sugar contents of 213

10

and 314 kcal/100g in both fresh and dried forms respectively. An adult human male and

female requires the energy with amount of 2300-2900 and 1900-2200 kcal day-1

,

respectively. Date fruit (100 g flesh) provides an approximate energy of 12 to 15% for

each adult each day. Sugars such as glucose, fructose and sucrose are the key sugars and

are the major components of the date‟s fruit being a vital and rich energy source for

human beings. Glucose plays an important role to elevate the level of blood sugars

because it is freely absorbed in digestive tract of the human body (Liu et al., 2013).

However, the presence of this amount in fresh and dried dates varies from variety to

variety, different maturation phases and climatic conditions (Barreveld, 1993). Dates are

an important constituent of dietary fibers (soluble, insoluble and total dietary), mainly

celluloses, hemicelluloses, pectin and lignin. The amount of total dietary fiber varies from

7.5 g/100 g to 8.0 g/100 g in freshly consumed and dried dates, respectively. The date

fruit comprised of 25 g per day of total dietary fibers which is enough to fulfill the

recommended daily intake (RDI) requirement of the body (Marlett et al., 2002). Hence,

dates are good source of dietary fibers in daily human beings diet.

2.3.3 Biological and curative significance

In ancient times, date fruits and seeds have been used as medication in numerous

traditional systems where date palm is cultivated (Duke, 1992; Khare, 2007). Worldwide,

dates are commonly used due to its biological significance for human beings as it contains

anti-oxidant and anti-mutagenic properties (Vayalil, 2012). According to an ethno-

medicinal survey, dates have been traditionally used for the treatment of hypertensive and

diabetics patients in southeast Morocco (Tahraoui et al., 2007). Old Egyptians used dates

as a vital tonic component in numerous aphrodisiac and different types of confectionaries.

They intake the date palm male pollens and flowers on regular basis as a source of sex

stimulants or to enhance the male fertility (Khare, 2007; Zaid, 1999). Old Hindus

consumed dried dates as medicines in their routine life to balance the body system. The

regular intake of dates is supposed to strength the body system, prevents the early hair

graying, formation of crumples and provides a lush and glossy outlook to the body skin.

The seeds of date palm fruits have been used as anti-aging tonic and to diminish the

crumples formation in women‟s skin (Bauza, 2002). The flesh of date fruits boiled in the

milk until it becomes soft and then consumed as a tonic for mothers during pregnancy as

highly nutritious food (Puri et al., 2000). Date fruits are thought to strengthen the gums in

babies having teeth problems (Zaid, 1999).

11

It is believe that intake of cooked dates with black pepper and cardamom to relief the

continuous pain in the head, dry coughs, tiredness, slight illness and loss of hunger (Zaid,

1999). Mastication of dried dates early in the morning plays a vital role to increase the

resistance power against common cold and to release the asthma (Zaid, 1999). Date fruit

is recommended for the patients of gastroenteritis, coughs, difficulty in breathing, chest

problems, illnesses, higher level of blood pressure and exhaustion (Khare, 2007; Selvam,

2008). Date fruit contains antioxidants and antimutagenic properties which gives

protection against a number of long-lasting ailments e.g. cancer and cardiovascular

illnesses (Al-Farsi et al. 2005b; Vayalil, 2012, Allaith, 2008). Date fruits are widely used

for manufacturing of drinks and alcohol as traditional medication, tonics, sex stimulants

and treatment of tumor patients (Al-Qarawi et al., 2005). Muslims have a faith that

“Person who consumes seven dates early in the morning for each day he will not be

affected by any kind of poisonous or magical effects on the day he consumed these dates”

(Miller et al., 2003). Dates are rich in insoluble fibers which minimize the danger bowl

cancer and diverticular disease (Marlett et al., 2002). Fully ripened dates contain higher

amounts of sugar contents (glucose and fructose) as compared to other fruits. These

sugars exert a number of valuable effects on the human health. Occurrence of high

amounts of fructose in dates may provide several beneficial effects on human health by

delaying or preventing the long-lasting diseases. It has been reported that minute amounts

of fructose increases the carbon flux with the help of an enzyme glycogen synthetase

which stimulates the synthesis of glycogen (Van Schaftingen and Davies, 1991; Shiota et

al., 2002; Watford, 2002).

2.4 Nutritional composition of date fruit

The fruit of date palm is an important and rich source of nutrition for humans as it

provides a large amount of sugars, salts, minerals, fibers, vitamins, phytonutrients, fatty

acids, protein and amino acids etc. Thus dates are considered as highly nutritious when

consumed with other food items (Lambiote et al., 1982) and mostly people consumed

dates in the form of fresh or dried. Vayalil (2012) widely studied that date fruit has a great

health potential as medicinal diet for the ailment of different types of human diseases.

2.4.1 Sugars composition

Carbohydrates are the main chemical components found in date fruit, mainly invert or

reducing sugars such as glucose and fructose and sucrose (non-reducing) and minute

12

amount of little concentrations of starch and cellulose (Al-Shahib and Marshall, 2003).

Based on sugar content, dates are of two types: invert sugar containing dates and sucrose

containing dates (Sawaya et al., 1983). During date fruit development and especially with

the progression of ripening, a remarkable increase in total sugars such as reducing sugars

and sucrose was noted. In date palm during the kimri, khalal and tamar fruit maturity

stages, level of TSS total sugars increased progressively depends upon the cultivars and

climatic conditions (Bacha et al., 1987). This rise in sugar composition from different

maturation stages (kimri to tamar) stage is directly linked with water contents during

these phases (Al-Shahib and Marshall, 2003). However, at hababouk stage, no soluble

sugars have been noticed (Eltayeb et al., 1999) while at kimri stage, invert sugars rapidly

increases and level of sucrose increases at khalal stage. Whereas, at rutab stage, fruit loses

its weight due to loss of moisture contents and sucrose in converted into invert sugars

(Morton, 1887; Myhara et al., 1999). During date fruit development, sugar accumulation

reached to a maximum level at tamar stage with predominant invert sugars (Morton,

1887; Bacha et al., 1987). At tamar stage, the flesh of date fruit contains highest

concentration of total soluble solids and invert sugars due to decreased water contents

(Tafti and Fooladi, 2006). Eltayeb et al. (1999) found that in some Omani date varieties,

fructose is the only sugar at kimri and khalal stages. However, during storage the fructose

concentration increased due to loss of moisture contents. In some soft and semi-dry date

cultivars, the sucrose is hydrolyzed into reducing sugars and in fully matured dates

(Mejdool and Boufgouss), no sucrose is noted, however in Deglet Noor contains the

sucrose as a dominant sugar at the time of fruit harvesting (Djerbi, 1996).

Generally, in invert sugars same trend was noticed as in total sugars (Gasim, 1994). At

rutab and tamar fruit ripening stages, maximum sugars concentration was noted due to

more photosynthetic activity and higher activity of invertase enzyme (Eltayeb et al.

1999). Soft dates contain lower level of sucrose than as compared to dry dates (Tafti and

Fooladi, 2006) and these contains glucose and fructose, excluding limited varieties which

contain sucrose (Eltayeb et al., 1999). Semi dried dates have about 50% sucrose and

invert sugars (Morton, 1987) and Eltayeb et al. (1999) reported that in semi dried dates,

higher amount of sucrose is recorded as compared to invert sugars. A date cultivar

„Deglet Nour‟ cultivated in California contains only sucrose sugar (Ensminger et al.,

1995). Date cultivars grown in Saudi Arabia comprised of about 70% invert sugars with

nearly same quantity of glucose and fructose (Tafti and Fooladi, 2006). A study carried

out in the United Arab Emirates on 12 date palm cultivars showed that level of glucose

13

and fructose increased in a rapid way as the fruit goes to developmental phases, and

moisture contents decreased during ripening and reached its lowest level at harvest

(Ahmed et al., 1995). In soft or invert sugar cultivars almost sucrose is converted into

invert sugars. Presence of plenty of sugars in date fruit have an important marketable

characteristic in both fresh intake and as processing. The presence of this huge amount of

sugars in date fruits recommends that it could be a potential source of refined sugar in

agro-industry (Samarawira, 1983).

2.4.2 Phytonutritional composition

The fruit of date palm is an important source of phytochemicals such as antioxidants,

phenolic compounds, sterols, carotenoids, anthocyanins, procyanidins, tannin and

flavonoids contents. The production or accumulation of these components depends upon

the type of fruit, harvesting stage, locality and type of soils. These phytonutrients have a

role in the nutritional and sensorial characteristics of date fruit (Abdelhak et al., 2005;

Abdul and Allaith, 2008; Al Farsi et al., 2005b; Ahmed et al., 1995; Fayadh and Al-

Showiman, 1990; Hulme, 1970). Dried dates contains contain higher amounts of these

phytonutrients as compared to other kinds of dates which represents a strong relationship

among antioxidants, phenolic compounds and flavonoids (Biglari et al., 2008).

2.4.2.1 Antioxidants composition

Dates are an important source of antioxidants especially freshly harvested dates (Al-Farsi

et al., 2007) but their ability is found in variable amounts in various cultivars and

different maturity stages that might be due to the change in phenolics. Dramatic changes

occurred in the composition of antioxidant phenolics as fruit goes to ripening phase and

this can affect the post-harvest life (Brady, 1987). Substantial quantities of efforts have

been conducted on physical and biochemical changes in date fruit during its growth and

development (Myhara et al., 1999; El Arem et al., 2011). However, very short reports are

available on the total phenolics, antioxidants (Amoros et al., 2009; Awad et al., 2011),

and tannin contents (Myhara et al., 2000) of dates during different maturation phases. The

hydrophilic activity of antioxidants is higher which is interrelated to phenolics, but the

activity of lipophilic antioxidants is very low with no changes during the fruit

development (Amorós et al., 2009). Overall, date fruit is regarded as rich source of

natural antioxidants having antiradical activities.

14

2.4.2.2 Phenolics composition

The total phenolics in date fruits are found in variable amounts which depend upon the

cultivars and extraction methods that create unacceptable assessment quantitatively. At

early fruit maturity stages phenolics are present in higher amount than later stages

(Biglari et al., 2008). Drying is considered as un-favorable as there are chances of

oxidative breakdown either through enzymes or degradation of phenolics due to heat

(Shahidi and Naczk, 2004). Though, the increase in phenolics were observed in few

cultivars after drying due to the tannins degradation by heat and different ripening

enzymes which involves during whole the dehydrating procedure, which release phenolic

compounds and break the linkage between p-coumaric acid and lignin and between

ferulic acid and arabinoxylans due to high temperature (Maillard and Berset, 1995). It has

been reported that in fresh and dried dates of Fard date palm cultivar, phenolics

efficiently increased because of tannins degradation and maturation of degradative

enzymes at high temperature (Al Farsi et al., 2005b).

2.4.2.3 Flavonoids composition

In plants, flavonoids are present in abundance amounts and hold a lot of beneficial effects

on health such as antioxidants and radical scavenging activities. Flavonoids present in

plants possess diverse health benefits, which includes antioxidant and radical scavenging

activities, to relieve some long-lasting illnesses, decreased the heart problems and

different types of tumors (Tapas et al., 2008). Hong et al. (2006) measured the thirteen

different types of flavonoids in „Deglet Noor‟ cultivar at khalal phase. Now a days date

fruits have a unique significance due to the presence of huge amounts of flavonoid

sulfates in the food (Hong et al., 2006). Chaira et al. (2009) reported that Tunisian date

cultivars „Korkobbi‟ contain higher amounts of flavonoids contents.

2.4.2.4 Polyphenols composition

Polyphenols are also an important constituent found in date fruit and making up to 3% of

the date flesh on dry weight basis (Hashempoor, 1999). The principle role of these

polyphenols is to convert the astringent taste of the fruit into tasteless form mainly due to

the reaction with protein (Hashempoor, 1999). The concentration of astringency in fruits

at different maturation phases depends upon the intensity of tannin contents, lesser the

level of tannin contents fruits were less astringent (Myhara et al., 2000). The level of

tannin contents is recorded more at immature green kimri stage (Messaïtfa, 2008) but its

15

concentration decreased rapidly as the fruit enters into mature khalal phase (Mohamed,

2000; Messaïtfa, 2008) and gradually decreased at rutab ripening phase (El-Agamy et al.,

2001) and fastly declines at last stage of maturity (tamar) and reached to a lesser level

(Bacha et al., 1987). Tannins in date fruits play a double role in taste observation and

helps in the color development during the ripening and storage (Hashempoor, 1999). As

well as the date fruit drops from its greenish color and fruit turns into reddish or yellowish

color, tannin contents are stored in cells and convert into unsolvable components. In dates

a thin coating of tannins is present at immature green kimri stage under the fruit skin

which makes the fruit astringent in taste. Booij et al., (1992) reported that a significant

decrease in tannin contents occurs as the fruit proceeded from immature kimri stage to

mature khalal to rutab and finally tamar stage in „Deglet Noor‟ cultivar. In dates, mostly

blackening occurs after harvesting due to the presence of tannin contents (Hashempoor,

1999).

2.5 Activities of enzymes during date fruit maturation

In date palm the most important enzymes found at different fruit maturation phases are

invertase, polygalacturonase (PG), pectin methyl esterase (PME), cellulase, and

polyphenol oxidase (Rohani, 1988; Fallahi, 1996). Invertase is the most active enzyme

found at rutab stage of fruit maturation (Al-Kahtani et al., 1998). Mostly in soft date

cultivars the activity of invertase is high and it is the most affecting date‟s fruit quality

enzyme. It is considered as the most responsible enzyme for the accumulation of invert

sugars at tamer phase of fruit maturity (Vandercook et al., 1980). The activity of invertase

noted higher at later fruit developmental stages (Zare et al., 2002). In soft date cultivars,

invertase hydrolyzed the sucrose into glucose and fructose but to some extent in semi-dry

and dry date cultivars (Biglari, 2009). Dried date cultivars contains little or no invertase

enzyme whereas, a small quantity of this enzyme if found in semi-dried dates as

compared to soft dates cultivars have maximum level of invertase (Hui, 2006; Eltayeb et

al., 1999). Invertase enzyme in date fruit is sensitive to high temperature and storage

duration (Zare et al., 2002). During date fruit ripening, there is conversion of protopectin

into water soluble pectin through the combination of PG and PME (Biglari, 2009, Al-

Jasim and Al-Delaimy, 1972). At kimri stage PG is not present but it progressively rises

as well as fruit goes to maturity (Mustafa et al., 2006). The higher activity of PG enzyme

found at later red or yellow fruit developmental stage and soft date cultivars showed

higher level of this PG activity (Hasegawa et al., 1969). In date fruit a adjacent

16

correlation found among the PG activity and fruit softening throughout ripening

(Hasegawa et al., 1969; Eltayeb et al., 1999). The activity of PG is found maximum in

soft dates (Hui, 2006). As the fruit goes to khalal and rutab fruit maturity stages, PME

activity increases (Biglari, 2009) which are mainly due to loss of pectin content (Al-

Shahib and Marshall, 2003). The activity of cellulase rises as the date fruit matures (Hui,

2006). At kimri phase cellulase is absent and its activity rises as the fruit goes to maturity,

reaching its highest level at final rutab phase while it remains constant at tamar phase of

fruit development (Hasegawa and Smolensky, 1971). Fruit softening in dates is mainly

occurred due to the breakdown of cellulase to cellulose into more soluble constituents,

ultimately glucose with decreased fiber contents (Biglari, 2009). The polyphenol oxidase

is the enzyme which is mainly involved to break down the tannins. The activity of

polyphenol oxidase remains higher at kimri stage than khalal and tamar date fruit

maturation phases (Hui, 2006). The natural brown color of all date fruit might be due to

the activity of polyphenol oxidase by oxidation of polyphenols (Al-Qarni, 2005).

2.6 Fruit classification on the basis of ripening

Harvesting of fruits should be practiced at their accurate physiological maturity and status

of ripeness (Harman and Patterson, 1984). Fruits are classified into two classes depends

on the respiration pattern and production of ethylene; as climacteric and non-climacteric

fruits.

2.6.1 Climacteric fruits

These types of fruits can be ripened of after harvest at proper physiological maturity. At

maturity both the respiration and ethylene generation however negligible at ripeness,

increased drastically as the fruit ripening progressed just at the start but it further declines

(Gamage and Rehman, 1999). Ripening is escorted by a piercing rise in respiration and

ethylene generation in such type of fruits. Ethylene production at during fruit ripening is

supposed to regularize the entrance of several genetic factors associated with ripening

which are liable for ethylene synthesis, break down of cell wall components, loss of green

pigments, carotenoids formation, and transformation of starch into sugar (Gray et al.,

1992; Theologis, 1993; Alexander and Grierson, 2002). The date palm is a climacteric

fruit because the respiration rate is more during fruit growth which preceded the higher

ethylene production and then it decreases as the fruit goes to maturation phase but again a

rise in ethylene production occurs as fruits goes to ripening stage (Abdel-Latif, 1988).

17

2.6.2 Non-climacteric fruits

Such kinds of fruits are not accomplished their ripening progression, when they are

removed from the mother plant. At this stage a little amount of ethylene is produced in

fruits which do not give any response after the application of exogenous ethylene

production. Such fruits show relatively slow decline in the respiration rate and ethylene

formation, during progression of ripening (Gamage and Rehman, 1999). These fruit do

not demonstrate any significant change in their respiration rate and production of ethylene

which persists at a minor degree. Nevertheless, in certain plant species, various features

of ripening, such as loss of green pigments and fruit softening occurs in fruits due to the

accumulation of precise ethylene level (Goldschmidt et al., 1993; Wills and Kim, 1995).

2.7 Fruit ripening mechanism

Ripening involves a number of physiological and biochemical alterations after the

maturation in fruits. It can be defined as variations that "happen since the final phases of

progression and expansion over the initial phases of senescence and outcome in

distinguishing aesthetic and/or food value" (Watada et al., 1984). A varied range of

biochemical variations occur in fruits during ripening such as increased rate of

respiration, loss of green pigments, carotenoids formation, anthocyanin and improved

action of cell wall loosening enzymes (Brady, 1987). During ripening the loss in color is

mainly due to the degradation of chlorophyll and disassembling of photosynthetic

mechanism and creation of numerous forms of anthocyanin and their buildup in vacuoles

(Tucker and Grierson, 1987; Lizada, 1993). Fruit flavor enhancement is owing to an

overall rise in sugariness that is due to enlarged gluconeogenesis, polysaccharides

hydrolysis, chiefly starch, reduced acidity, and build-up of sugars and organic acids

(Grierson et al., 1981; Lizada, 1993). In fruit, firmness is mainly linked with

disassembling of the cell wall (Seymour and Gross, 1996) and alterations in the level of

pectin are certain understandable variations in the fruit outer layer during ripening

(Marin-Rodriguez et al., 2002). Various types of enzymes such as PE, PG and PL plays

an important role during the fruit softening and solubilization of pectin and starch

hydrolysis (White, 2002) and starch hydrolysis.

2.8 Date fruit maturation and development

The date fruit ripening is a complex phenomenon which involves the breakdown of

chlorophyll, carotenoids formation, degradation of cell wall and transformation of starch

18

into sugars (Eltayeb et al., 1999). Date palm plant bears fruit only once a year as its fruit

development or maturation period is very length and it takes about 6-7 months. A large

number of physiological and biochemical changes occur during all these maturation

stages. During the fruit formation and ripening date fruit passes through five different

phases i.e. Hababouk (baby fruit), Kimri (immature fruit), Khalal (full colored mature

fruit), Rutab (soft brown) and Tamar (hard raisin like appearance) and these are common

Arabic terms but also accepted in English languages (Fayadh and Al- Showiman, 1990;

Al-Shahib and Marshall, 2003; Fadel et al., 2006).

2.8.1 Hababouk stage

It is the earliest stage of fruit development which starts after fertilization and it lasts for 4

to 5 weeks by the loss of two unfertilized carpals (Eltayeb et al., 1999). The fruits are

immature and also called as‟ baby fruit‟ which turns into calyx (fruit cap). At this stage

the fruit is just like a pea sized, round, creamy to faint green in color and weighs up to a

gram by holding the moisture content of 85 to 90% (Al Noimi and Al-Amir, 1980;

Ahmed et al., 1995; Al-Shahib and Marshall, 2003; Fadel et al., 2006).

2.8.2 Kimri stage

It is the longest stage (period) of date fruit development and it appears in first 17 weeks

after fertilization (Morton, 1887) depending upon location and cultivar. The fruit at this

stage remains immature young, elongated (Eltayeb et al., 1999) and hard surface with

greenish color (Hui, 2006). In this phase fruit weight increases and tannin concentration

reached at maximum level (Eltayeb et al., 1999). It is categorized into two stages. In first

stage, fruit size and weight rapidly increases with more sugars accumulation and water

contents. While in seconds phase, reduction in fruit size, weight, acidity and sugars

occurs with higher water contents as compared to first stage (Fallahi, 1996; Hashempoor,

1999; Najeh et al., 1999; Al-Shahib and Marshall, 2003).

2.8.3 Khalal stage

This stage starts next 6 weeks to kimri phase (Morton, 1987) in which the fruit gains its

maximum size and weight, turns into yellowish or reddish color depends upon the variety

and surface is hard (Hui, 2006). At this stage fruit volume, sugars, acidity and water

contents continuously decrease. Sugars accumulation gradually increases and this phase

takes about 5 weeks for completion depends on the cultivars (Eltayeb et al., 1999). In this

19

fruit maturation stage, mostly fruit is consumed in raw or fresh form or used for making

of jams and date syrup (Hui, 2006).

2.8.4 Rutab stage

This stage remains 4 weeks (Morton, 1987) after khalal stage and fruit loses water

contents (Al-shahib and Marshall, 2003). At this stage, fruit starts ripening from the point

of apex and fruit becomes firmer, sweet in taste with dark brown appearance, lower

astringency, and sucrose transforms into glucose and fructose (Morton, 1987). Fruit starts

to lose weight due to consistent loss of water contents (35-40%). The concentrations of

total sugars and SSC were increased and sucrose is converted into reducing sugars with

minimum intensity of tannin contents (Al-Hooti et al., 1995; Ahmed et al., 1995; Fadel et

al., 2006) and this phase is the beginning of fruit ripening (Najeh et al., 1999). Fruits of

this stage are mainly consumed as jams, date bars paste etc. In some cultivars the fruit at

this stage is mostly eaten as fresh rutab dates which are highly nutritious and full of

energy (Hui, 2006).

2.8.5 Tamar stage

This is the last phase of date fruit ripening and it takes about two weeks depends on the

variety (Morton, 1987). At this stage, fruit attains higher amounts of SSC, sweeter, less

astringent, and softer and color turns into darkish brown with presence of furrows on the

outer surface (Hui, 2006). At this phase, glucose and fructose are present in abundance

while sucrose is lacking (Al-Hooti et al., 1997; Myhara et al., 1999). Fruits of this stage

loses higher amount of water for with accumulation of more sugars which plays an

important role for the prevention of fermentation (Najeh et al., 1999). In dried varieties,

the fruit of tamar stage becomes light colored with hard surface as compared to soft date

varieties (Fallahi, 1996). The fruit of this stage is almost used for storage purpose due to

presence of lower water contents and higher amounts of sugars (Hong et al., 2006; Awad,

2007). These dates can be used for storage up to one year under ambient conditions if

firmly pressed (Najeh et al., 1999).

20

Khalal stage (cv. Khadrawi)

Rutab stage (cv. Khadrawi)

Tamar stage (cv. Khadrawi)

Slide-2.1: Different edible stages of Khadrawi fruit

21

Khalal stage (cv. Hillawi)

Rutab stage (cv. Hillawi)

Tamar stage (cv. Hillawi)

Slide-2.2: Different edible stages of Hillawi fruit

22

2.9 Monsoon rains and dates industry

Date palm industry is highly affected due to the occurrence of monsoon rains at the time

of fruit harvesting and ripening which starts from July to August. Mostly the dates are

harvested during these months at different maturity stages according the customer

demands. Most of the growers harvest the dates at mature khalal or early rutab stage and

process them into dried dates (Khajoor) after adopting hydration or de-hydration

techniques to fulfill the market demands. The occurrence of rains during this period is

very harmful especially for the fruits which were going to be harvest. Experts say that

these rains destroy up to 60% of dates and in few cases this harm may go to 100%

damage of the dates. This threatening situation is not bearable for the poor date growers

as they wish to earn some money for their living after a long span of field work. This

condition becomes further worsens when the poor growers do not save a little part of their

crop from full flourishing fruit crop (SBI, 2011). Date palm growers mostly convert the

dates in full dried form (Chohara) with less economic value by harvesting the fruit at

early maturity stage (un-ripened) to avoid the risk of monsoon rains. Similarly they adopt

old drying techniques which decreased the quality of the produces under unhygienic

conditions which harshly affects their profit. Processing of dates through such ways or

means contributes about 20 to 30% post-harvest losses every year (ASF, 2010).

2.10 Fruit ripening agents

The ripening agents probably disturb the epidermal cells and protoplasm, thus liberating

and triggering the activity of enzymes. Ripening by contribution of enzymes different

enzymes such as invertase, polygalacturonase (PG), cellulase, polyethylene (PE) and

peroxidase (PO), causes alterations in the structural parts e.g. pectin and cellulose that

grasp the cells organized, to become soluble, and tannin contents precipitates. Hence, it

facilitates the ripening process of fruits from khalal to tamar, which involve; precipitating

out of tannins, increasing small sugars causing sweetness, texture softening, color

changes and other ripening related quality compositional characters. This degree of

modification is variable depends upon the fruit maturation phase and lot of others

environmental factors which are liable for the ripening and or curing of date fruits

(Shamshiri and Rahemi, 1999).

23

2.10.1 Ethephon (2-chloroethyl-phosphonic acid)

The fruit ripening hormone ethylene is released by ethephon which is hydrolyzed in plant

tissues and initiates the ripening in climacteric fruits, is now commercially used in various

fruit species (Cooke and Randall, 1968; Warner and Leopold, 1967). The main reaction

which is generated by the ethephon is to breakdown the ethylene (Anderson, 1968).

Ethephon is now being widely used in agriculture sector for the promotion of flowering,

defoliation, and fruit ripening and so on. Ethephon applications had to be accompanied

with severe pruning in order to be able to enhance ripening of Samany dates (Hussein et

al., 1993). Thus, many researchers have been attempting to accelerate ripening of dates

after harvest (Khalifa et al., 1975; Rouhani and Bassiri, 1977). It was found that due to

the hydrophilic nature of ethephon, its diffusion across the cuticle is very slow (Farag,

1989) and its penetration across the cuticle could be enhanced by changing its

formulation (Farag and Palta, 1992). Application of ethephon in newly emerging fruits

and leaves increased the level of ethylene in two days. In most of the fruit crops ethephon

plays a vital role to enhance the chlorophyll degradation and carotenoids formation

(Sonkar and Ladaniya, 1999; Drake et al., 2006). The effectiveness of ethephon depends

upon its rate (Sims et al., 1970; Knavel and Kemp, 1973), time (Hoyer, 1996),

formulation (Conrad and Sundstorm, 1987), fruit maturation phase (Beaudry and Kays,

1988; Hoyer, 1996; Kahn et al., 1997), and environmental features (Beaudry and Kays,

1988). Ethephon hasten and liberate the fruit maturation cycle in pepper fruits as a

ripening agent (Sims et al., 1970; Batal and Granberry, 1982). Fruit maturity is the key

factor which affects the ethephon efficacy during the ripening of pepper fruit (Batal and

Granberry, 1982; Armitage, 1989). Furthermore, initial application of ethephon after fruit

set resulted in a significant yield reduction (Mougheith and Hassaballa, 1979). The

application of ethephon is known to increase total soluble solids contents (Khalifa et al.,

1975; Rouhani and Bassiri, 1977). Application of ethephon before and after harvest

mostly causes the changes in skin color however; some internal compositional changes

have also been reported such as TSS, sugars, and juice contents increased (Mazumdar and

Bhatt, 1976) while loss of green pigments, level of acidity, and vitamin-C contents

decreased during degreening (Ramana et al., 1973; Singh et al., 1978).

2.10.1.1 Pre-harvest ethephon application

Pre-harvest ethephon application with different concentrations gives irregular results

regarding the color development and defoliation which linked to each other (Stewart,

24

1977). Pre-harvest ethephon hasten the fruit maturity time in apples (Edgerton and

Blanpied, 1970). According to Kamal (1995) revealed that fruit ripening enhanced about

one month by foliar application of ethephon in „Zaghloul‟ and „Samani‟ date palm

cultivars. The significant increase in rutab fruit yield per bunch was noted in date palm

cv. Hilali by pre-harvest application of ethephon either it sprayed or injected two weeks

from fruit color turning phase as compared to untreated fruits (Awad, 2007). Fruit

ripening accelerates by about one month with application of ethephon @ 1500 ppm in

„Zaghloul‟ and „Samani‟ date cultivars soon after complete blooming (Kamal, 1995).

Musa (2001) revealed that by injecting ethephon @ 2 ml/bunch in „Mishrigi Wad Khatib‟

and „Mishrigi Wad Lagi‟ cultivars fruit ripening time accelerates two to three folds than

fruits those were sprayed with ethephon @ 1000 ppm.

Pre-harvest application of ethephon also accelerates the fruit maturation time in other fruit

crops. In rabbiteye blueberry the application of ethephon promotes the fruit ripening,

however the stimulatory action of ethephon on the ripening of fruits was dissimilar

regarding the fruit grade and ripening properties (Ban et al., 2007). Similarly, in apple

and cranberry the influence of ethephon has been well known for the improvement of skin

color (Murphey and Dilley, 1988). In Satsuma the fruit ripening accelerates by fifteen to

twenty days with uniform and thin peel and superior bio-chemical composition by the

application of ethephon before the onset of yellow fruit stage (Nodiya and Mikaberidze,

1991). In Beladi oranges the application of ethephon two times before fruit colour break,

improved the chlorophyll breakdown and increases the production of carotenoids (Al-

Mughrabi et al., 1989). The commercial application of ethephon is done two to three

weeks in „Delicious‟ apples before harvest to increase the fruit color development and

obtain early maturity (Hammett, 1976). It has been shown that ethephon accelerates the

physiological process of fruit maturation by promoting the ethylene production in blue

berry plants (Lieberman, 1979). Prohens et al. (1999) reported that ethephon spraying @

500 mg/L improves the earliness and fruit quality without any significant effect on yield

in the hybrid clones of pepino (Solanum muricatum Aiton). In „Delicious‟ apples the

application of ethephon at early fruit maturation phases accelerates the fruit ripening to

breakdown the cell wall and soften the fruit tissues (Curry, 1994). Bal et al. (1996)

reported that pre-harvest application of ethephon @ 400 ppm hasten the fruit ripening

period of ber (Zizyphus mauritiana Lamk.) by about two weeks. In Figs, pre-harvest

ethephon application (at the end of slow growth period ), when most of the basal figs

showed color break, stimulated the growth and shortened the maturity period of fruits

25

without any adverse effect on fruit quality. The fruits those were treated started to ripen 5

days earlier than untreated ones, and most of the fruits were harvested when control fruits

had just started to mature (Çelikel et al., 1997). Kim et al. (2004) elucidated the effect of

ethephon on fruit quality and maturity of astringent persimmon cv. Tone Wase and

reported that ethephon accelerates the fruit maturity by 13 to 22 days when sprayed 120

days after bloom. According to Yuzo and Tomoya (2002) that ethephon application 140

days after full bloom in 'la France' accelerated the harvesting time by about 5-10 days.

Ross (1993) revealed that ethephon at 1000 to 1500 mgL-1

significantly increased the fruit

soluble solids concentration and substantially reduced the fruit starch when applied 12 to

26 days after full bloom in apple (Malus domestia Borkh., spur „Delicious‟ strains). Pre-

harvest application of ethephon was found to enhance the ripening processes and

noticeably increased the total soluble solids (Mougheith and Hassaballa, 1979). Pre-

harvest ethephon application was also found to improve the fruit quality composition

(Maximos et al., 1980), SSC, sugars, and juice percentage increased (Mazumdar and

Bhatt, 1976) while degradation of chlorophyll and level of acidity and vitamin-C contents

lower down during degreening (Ramana et al., 1973; Singh et al., 1978). Juice percentage

and total soluble solid remained higher in fruits those were sprayed with ethephon before

harvesting (Chauhan and Rana, 1974; Soni and Ameta, 1983).

2.10.1.2 Postharvest application of ethephon

Most of the citrus species i.e. oranges, tangerine, grapefruit, and lemon when dipped in

the solutions of ethephon for a few seconds to quite a few minutes gave attractive colour

within 7-10 days after application (Fuch and Cohen, 1969; Yong et al., 1970). In Meiwa

kumquat fruits the orange red fruit colour developed by the application of ethephon (400

ppm) and a rapid increase in color development was recorded in treated fruits than non-

treated fruits which were stored at 10oC. The application of ethephon at the rate of 5%

increased the average fruit weight and peel/fruit and juice/fruit ratio by reducing the

acidity without affecting the sugar composition (Hashinaga and Itoo, 1985). Dipping of

mango fruits in ethephon @ 1000-2000 mgL-1

for 1 to 2 min accelerates the ripening with

acceptable product quality (Sergent et al., 1993). Fresh market pineapples (Ananas

comosus L.) treated with ethephon produced uniform full yellow color 2-3 days earlier

than untreated ones with superior eating quality (Smith, 1991). In „Coorg‟ mandarins

color was improved by ethephon dipping @ 1000 ppm (Ramana et al., 1973). In Green

Valencia and Mosambi sweet oranges, yellow color appeared in 5-7 days when fruits

26

were dipped in ethephon @ 1000-2000 ppm under ambient conditions (Arora et al., 1973;

Chauhan and Parmar, 1981; Purandhare et al., 1992). Treatment of Mosambi oranges

with ethephon dipping @ 3000 ppm showed superior bright yellowish color in short time

(Sanghvi and Patil, 1983).

2.10.2 Application of NaCl and acetic acid

Acetic acid is a universal metabolic agent and occurs in plants and animals. It is a plant

bio-regulating agent which belongs to auxin group and plays a crucial role for some

particular physiological processes within the plant body. These bio-regulators can speed

up or slow down the growth or maturity rate or otherwise change the plants action or their

products (Lemaux, 1999; Olaiya and Osonubi, 2009). In date palm fruit ripening with salt

and acetic acid is insufficient and only a few evidences are reported which are variety

specific (Kalra et al., 1977; Asif and Al Taher, 1983). Saleem et al. (2005) reported that

NaCl (2%) is more effective to accelerate the fruit ripening in „Dhakki‟ date palm cultivar

with good quality fruits as compared to untreated fruits. It has been reported that CaCl2

plays an important role to reduce the post-harvest problems and improved the produce

quality during the ripening (Stanly et al., 1995). Furthermore, it improves the strength

ability of fruit skin and makes the cell wall and tissues more resistant against different

types of infections (Mignani et al., 1995; Hong et al., 1999). It has been documented that

by increasing the salt concentration, ripening increased progressively in Khadrawi and

Shamran cultivars while by adding acetic acid showed greater effect (Kalra et al., 1977).

Sodium chloride (3-6 gL-1

) significantly increased the fruit ripening characters such as

color, flavor, and production of ethylene and rate of carbon dioxide production.

Farahnaky and Afshari-Jouybari (2011) conducted a study on „Mazafati‟ date cultivar by

incubating the fruits in hot solution of acetic acid 0.5% at 40 ± 1oC for 72 h. They

reported that the treated fruits contain more TSS and acidity than control fruits. Great

losses of fruit softness were recorded for the duration of 12 h incubation and were

acceptable to the customers in terms of organoleptic properties. The applications of NaCl

and acetic acid alone or in combination significantly enhance the total soluble solids;

reduced the water contents and fruit firmness. Acetic acid (2%) showed superior effect on

fruit ripening than NaCl; however the fruits treated with NaCl were better in appearance

(Shamshiri and Rahemi, 1999). Farahnaky et al., (2009) indicated that during ripening of

„Kabkab‟ dates with NaCl and acetic acid, the moisture content and colour changed

significantly. The major change was observed for firmness where a maximum force for

27

puncture test varied from about 1000 to 50 g force for all samples after 72 h of incubation

at 40°C. Harvesting at khalal stage followed by treating the fruits with NaCl and/or acetic

acid solutions and an incubation stage at 40°C showed to be a promising method for

accelerating the ripening of „Kabkab‟ dates from khalal to tamar stage. Tafti and Fooladi

(2004) postulated that treatment of „Mozafati‟ fruits at the end of khalal stage with acetic

acid (4%) and placing them in a maturation room at 38-40oC with 70-80% relative

humidity for 3-5 days is the effective and economical method for artificial ripening of the

fruits. Chatha et al. (1985) reported that best curing of „Khadrawi‟ dates harvested at

khalal stage was performed in the solution of acetic acid at 0.09% + NaCl at 1.5%. Haq

(1990) treated the „Zahidi‟ dates for curing with acetic acid and NaCl alone or in

combination. He concluded that combined application of acetic acid (2.5%) + NaCl

(12%) showed significantly superior results by affecting the early ripening of the fruit and

make the fruit soft over all other treatments. Another study conducted by Mirza and

Meraj-ud-Din (1988) by treating the fruits of „Dhakki‟ and „Basra‟ cultivars at khalal

stage with 3% brine solution, 0.25% acetic acid and 0.25% citric acid solution for 5

minutes. Their results indicated that different chemical treatments enhanced the fruit

ripening process significantly with better fruit quality.

2.11 Hot water applications

Fruit and vegetables can be treated with heat by means of hot water dipping, vapor, or hot

dry air. Recently, extensive global concern in the heat treatment for maintaining the food

quality and diseases has been shown in many of the literatures. Water is the most efficient

and preferred medium in many of the applications than the others. Hot water treatments

have a number of benefits such as: comparatively simple in use, short time exposure,

consistent handling of fruits and temperature of water and burning of disease causing

agents with economic advantage as it is cheap as compared to other heat application

methods (Fallik et al., 1999; Garcia-Jimenez et al., 2004). Higher temperature exposure

in agricultural products alters the various physiological processes such as heat shock

proteins transcripts and different level of proteins in such type of products (Lurie, 1998).

Presently, hot water treatments in fruits and vegetable have got the extensive worldwide

attention for the maintenance of product quality and to control various types of diseases.

Higher temperature increased the intensity of heat shock proteins in exposed agricultural

products (Lurie, 1998). Moreover, heat affects a number fruit ripening processes which

includes the color (Cheng et al, 1988; Tian et al., 1996), ethylene production (Ketsa et

28

al., 1999), rate of respiration (Inaba and Chachin, 1988), firmness of fruits, breakdown of

cell wall (Lurie and Nussinovich, 1996) and formation of different volatile compounds

(McDonald et al, 1999). All the agricultural products showed a variable response to heat

treatments. Inappropriate application of heat to agricultural commodities can cause

ripening progression or heat damage (McDonald et al., 1999). Heat treatment triggered by

significantly increasing the rate of respiration and production of certain types of organic

acids (Lurie and Klein, 1990). The harshness of heat contact regulates the thermo

tolerance reaction of treated produce which depends upon the exposure temperature

(Lurie, 1998).

Hot water is an efficient means of heat transfer and it maintained the uniform

temperature within a short time limit (Couey, 1989). Hot water has been widely adopted

as heat disinfestation due to its effectiveness and more economic (Jacobi et al., 1995).

Heat treatments increased the thermal tolerance in exposed produce against various

environmental features such as time of application, duration and application type. These

can alter the fruit ripening by hindering, promoting and or disturbing all the processes

involved during the fruit ripening. In mango fruits, heat treatments accelerates the yellow

color and uniformity of the fruit skin, however fruit becomes softer in a number of

varieties (Jacobi et al., 2001). The concrete mechanism by which heat treatments

accelerates the ripening in mango fruits is still unknown. Post-harvest heat application in

fruits and vegetables plays a wide role to overcome the problems of diseases and insects

(Lurie, 1998). In banana fruits, hot water treatments stimulated the antioxidants activities

due to increase in phytochemicals and decreases of ethylene during the progression of

ripening which cause delay in banana fruit ripening processes (Nittaya et al., 2011). Hot

water treatments significantly affected the rate of respiration, C2H2 production and

activities of different ripening enzymes (aminocyclopropane carboxylic acid) in fruits

during ripening Marrero and Paull (1998). The exposure time of hot water treatments is

more effective as compared to the temperature of hot water during the ripening of banana

fruits Wall (2004). Higher temperature for long exposure significantly reduced the

conversion process of starch into sugars without any significant effect of total soluble

solids and acidity level. Bananas exposed at 51oC for 20 minutes had delayed respiratory

peaks and ethylene production. Mild peel injury was observed on fruits exposed to higher

temperatures (49-51oC) for longer durations (15-20 minutes).

Shahnawaz et al. (2012) reported that mango fruit treated in HW ripened earlier under

ambient conditions (38 ± 4oC) as compared to fruits those were untreated. These early

29

ripened mango fruits received higher organoleptic scores in terms of color, firmness,

taste, texture and aroma. Hot water treatments significantly increased the level of acidity

in ripened mango fruit under ambient conditions than untreated fruit. This rise may be

due to the degradation of bio-chemical constituents of the un-ripened fruits during

respiration, resulting in certain acids (Anwar and Malik, 2007). In another study HWT at

55oC and 45

oC has reduced the vitamin C content of mango as compared to control. This

attributed to susceptibility of ascorbic acid to oxidative destructions particularly slow in

hot water treatment as compared to ambient temperature. These findings were also

confirmed by Pudmini and Prabha (1997) and Thomas and Oke (1980) claimed that the

reduction of vitamin C during fruit ripening. Furthermore, total soluble solids of mango

fruit was significantly affected by hot water treatments. They reported that the increase in

total soluble solids might be due to the alteration in the cell wall structure and break down

of complex carbohydrates into simple sugar and this hydrolytic changes in starch is may

be due to hot water treatment whereas slow changes in TSS was also observed in control

samples. There was a gradual increase of total sugars in mangoes treated with hot water

treatment at 55oC and stored at room temperature as compared to 45

oC and control stored

at room temperature. The increase in total sugar level could be attributed mainly due to

breakdown of starch into simple sugars during ripening along with a proportional increase

in total sugars which was attributed to the increased activity of amylase and other

enzymes converted into sucrose, glucose and fructose during storage (Aina, 1990;

Rajwana et al., 2010). Increase in non-reducing sugar by HWT may be due to acidity by

physiological changes during storage (Anwar and Malik, 2007). Jabbar et al. (2011)

found that when fruits were given hot water treatment, reducing sugar remained higher

than non-reducing sugar throughout ripening process under ambient temperature. Carillo

et al. (2000) and Malik et al. (2003) reported that fruit pulp color turned into pale yellow

due to hot water treatment that increased enzymatic oxidation and photo discretion as

compared to control. Warm water at 45oC for 30 minutes increases the soluble solids

concentrate (SSC), weight loss, enhanced the fruit firmness, reducing the decay,

prolonging the shelf life and improving some quality characteristics in tomato fruit (El-

Assi, 2004). In date palm the hot water dipping temperature for artificial ripening of soft

date varieties ranges from 60-65oC (Kader and Hussein, 2009).

2.12 Application of thinning practices

In date palm, fruit thinning is a very critical managerial operation which effects the

development of fruits, gives early maturity, larger fruit size; regulate the tree yearly

30

bearing and better quality fruits by reducing the competition among the remaining fruits.

Fruit thinning is one of the main principles of commercial date production. Usually fruit

thinning is carried out physically or by using different chemicals. However, to avoid the

risk of various environmental issues or health hazards, thinning is considered as an

effective managerial approach for getting the desired quality traits.

Several methods have been used to thin the date palm trees such as bunch thinning,

strands thinning and single fruit removal thinning (Ali-Dinar et al., 2002). Combination

of single fruit removal and strands thinning had substantially improved the fruit quality in

„Medjool‟ date cultivar (Osman and Abdulrida, 1989). Thinning by progressive removal

of strands improves the physical and chemical parameters while overall yield was reduced

in „Sewi‟ date cultivar (Moustafa, 1993). The methods of thinning used in these

experiments included removal of part of the length of the strands (Tavakkoli et al., 1994;

Samavi, 1998; Sayyahpoor, 2002); removal of some of the entire central strands

(Tavakkoli et al., 1994); removal of some of the fruit on the strand (Tavakkoli et al.,

1994); and removal of some of the bunches (Davoodian, 1999). Removal of fruit bunches

at the intensity of 10 to 30% significantly increased the yield per bunch than fruits those

were untreated (Akl et al., 2004; El-Assar, 2005 and Alwasfy and Mostafa, 2008).

Removal of 30% strands from the center of the bunch resulted in better yield, accelerates

the ripening and produces superior quality fruit as compared to fruit without thinning in

„Shamran‟ and „Nabetet ali‟ (Godara et al., 1990; Al-Ghamdi et al., 1993). In „Zaghloul‟

date palm cultivar, shortening of strands or by reducing their number 2-4 weeks after

pollination positively increased the total soluble solids and sugars with optimum fruit

yield than un-thinned fruits (Khalifa et al., 1987; Abdel-Hamid, 2000; Hammam et al.,

2002; Bassal and El-Deeb, 2002; Marzouk et al., 2007 and Al-Wasfy and Mostafa, 2008).

Bloom thinning improved the fruit quality compositional parameters by regulating the

yield in „Zaghloul‟, „Haiany‟, „Seewy‟ and „Amry‟ date palm cultivars.

Removal of central strands four weeks after pollination led to optimum fruit quality in the

„Succary‟ date palm cultivar (Soliman and Harhash, 2012). Al-Obeed et al. (2005) on

„Succary‟ dates found that the shortening of strands by 40% gave the highest value of

total sugars. Bunch thinning significantly increased the fruit physical and biochemical

characteristics of tamar stage fruits in „Khalas‟ date cultivar (Soliman et al., 2011). Al-

Darwish (2010) found that fruit thinning reduces the fruit shrivel percentage and

improved the quality. Similarly fruit thinning increases the fruit size, accelerates the fruit

ripening, and minimizes the fruit drop and alternate bearing, one of the main principles of

31

commercial date‟s production. It increases fruit size and quality, reduces alternate bearing

and fruit drop, enhances the fruit ripening and has other advantages (Zaid, 1999).

Behseresht et al. (2007) reported that the thinning at kimri stage had no significant effects

on fruit quality and quantity when compared with that at pollination stage. Although,

removal of one third (control and strand-tip) of strands reduced yield; this treatment

increased fruits in top grade. Sayyahpoor (2002) reported that cutting 5, 10 or 15 cm of

the strand one week after pollination had no effect on fruit volume, but thinning intensity

@ 10 and 15 cm resulted in significant increases in fruit length and in fruit weight and

diameter of „Sayer‟ dates, respectively. Samavi (1998) also found that in „Mordasang‟

cultivar, removing the tip of strands @ 10 or 15 cm levels 3 weeks after pollination

improved the fruit size and weight but without affecting the fruit quality parameters such

as TSS and total sugar and also seed weight and volume. Furthermore, it has been

indicated that in „Shahani‟ cultivar, cutting back one third of the tip or central strands at

the beginning of kimri stage (identical to the treatments used in our study) increased the

fruit weight and length, pulp to seed ratio, fruit water content and TSS but did not affect

fruit diameter (Tavakkoli et al., 1994). It was also found that in „Samani‟ cultivar,

removing one third of the tips or central strands eight weeks after pollination resulted in

significant increases in fruit weight, length and diameter, pulp weight and fruit TSS

percentage. Khademi (1998) reported that cutting back one third of the central strands at

pollination time is much more effective to increase the fruit size and quality and

accelerating the ripening period of „Kabkaab‟ dates than the same treatment at the time of

bunch lowering at mid kimri stage. Hence in date palm fruit thinning is considered as an

important management practice to hasten the maturity or ripening and improves the

physical and biochemical composition by reducing the competition in remaining fruits.

The research findings described in the preceding lines throw light on the status and

challenges faced by date palm industry in Pakistan. It also suggested making some plan to

combat these challenges; therefore, the current studies were intended and executed.

32

Chapter-3 MATERIAL AND METHODS

The research studies reported in this manuscript were conducted during 2011-2012 on

two date palm cultivars including ‘Hillawi’ (Slide 3.1) and ‘Khadrawi’ (Slide 3.2),

commercially grown in Punjab, Pakistan. On the basis of texture, these are soft date

cultivars but completely consumed at khalal stage due to occurrence of monsoon rains at

the time of harvesting and/or ripening during the months of mid-July to August, which is

a peak monsoon period that badly affects the production, processing and quality of these

date palm cultivars.

Slide 3.1: Mature fruit of date palm at final kimri stage cv. Hillawi

Slide 3.2: Mature fruit of date palm at final kimri stage cv. Khadrawi

33

3.1 Experimental site description

The research work reported in this manuscript was conducted in the Experimental Fruit

Orchard Square Number 9 and Post Graduate Agricultural Research Station (PARS) and

Pomology Laboratory Institute of Horticultural Sciences, University of Agriculture

Faisalabad, Pakistan. Analytical work was conducted in the laboratories of Post-harvest

Research Centre, Ayub Agricultural Research Institute (AARI), Faisalabad, Pakistan,

Central High-Tech Laboratory, University of Agriculture Faisalabad and Biological and

Bioassay Laboratory of Chemistry and Biochemistry Department, University of

Agriculture Faisalabad, Pakistan.

3.2 Experimental material

The plants of two date palm (Phoenix dactylifera L.) cultivars ‘Hillawi’ and ‘Khadrawi’

having the age of about 20-22 years grown at Experimental Fruit Orchard Sq. No. 9 and

Post Graduate Agricultural Research Station (Latitude 31o-26´ N, Longitude 73

o-06´ E

and Altitude 184.4 m), Institute of Horticultural Sciences, University of Agriculture

Faisalabad, Punjab Province, Pakistan, were selected for this study work. All the selected

plants were uniform in size, manually pollinated and uniform agronomic practices

(fertilizers application and irrigation) were adopted throughout the period of

investigations (2011-2012).

3.3 Experimental details

3.3.1a Evaluating the potential of ethephon on ripening acceleration and fruit

quality of date palm at kimri stage.

Twenty one trees of each cultivar (Hillawi and Khadrawi) with uniform size and age were

selected as experimental material under RCBD (Factorial) with three replications (2

bunches per replication). A liquid plant growth regulator [(Ethephon 480g/L SL (48%

m/v)] was purchased from Shanghai Mingdou Agrochemical Co., Ltd. China. A wooden

step ladder was used for climbing up on the date palm trees during the experimentation.

Following concentrations of ethephon [(Ethephon 480g/L SL (48% m/v)] were applied at

final kimri stage with following treatments given as under.

T1: Control (without ethephon application)

T2: Ethephon spray @ 2 ml/L at final kimri stage



T5: Ethephon injection @ 1 ml/bunch at final kimri stage


34


3.3.1.1a Method of spray

For spraying ethephon was dissolved in 1000 ml water. Tween-20 at 0.01% was added as

surfactant with foliar application as a wetting agent. For each bunch 250 ml solution was

used as a spraying material. Spraying was done with a hand carrying plastic sprayer

having the capacity of 500 ml.

3.3.1.2a Method of injection

For injection a small pit was made in the peduncle with a sharp budding knife made up of

stainless steel. The pit was made 20 cm away from the start of fruiting and ethephon

solution was injected into the pit with the help of a 5 ml BD Plastipak TM Luer Tip

syringe (diameter: 12.05 mm) mounted with stainless steel needle having the dimension

of (21G×11/2”-0.08×40 mm). After injection pit was covered with cellotape to avoid any

contamination.

3.3.1.3a Fruit harvesting

During the entire harvesting season, rutab/ripe fruits were periodically collected from the

selected bunches and weighed. Fruits showing soft brownish tip were considered as ripe

or rutab fruits. From each replication 100 rutab fruits were randomly selected for physical

and biochemical analysis.

3.3.1b Effectiveness of ethephon on the ripening acceleration and physico-

chemical characteristics of date palm at khalal stage.

3.3.1.1b Methodology

Same methodology was adopted as mentioned in the section 3.3.1.1a regarding the

ethephon treatments, concentrations used, application procedure and fruits harvesting. In

this part of experiment, treatments were applied at color break stage (early khalal stage)

of both date palm cultivars.

35

Khadrawi fruit at final kimri stage Hillawi fruit at final kimri stage

Calibration of ethephon Ethephon spray

Removal of thorns Scaling for injection

36

Making pit for injection Injecting ethephon in the peduncle

Covering of injection site

Slide-3.3: Application of ethephon by foliar spray and injection

37

3.3.2 Exploring the role of thinning practices on the ripening and fruit quality of

date palm.

In this experiment, seven trees of each cultivar (Hillawi and Khadrawi) with uniform size

and age were selected as experimental material under RCBD (factorial) with three

replications (2 bunches per replication). The treatments detail is given below.

T1: Control (no thinning)

T2: 20% removal of central strands

T3: 30% removal of central strands

T4: 20% shortening of terminal tips

T5: 30% shortening of terminal tips

T6: 20% removal of central strands + 20% shortening of terminal tips (T2+T4)

T7: 30% removal of central strands + 30% shortening of terminal tips (T3+T5)

3.3.2.1 Method and time of thinning

Thinning was performed with a small hand carrying pruning scissor made up of stainless

steel at early kimri stage (4 weeks after pollination). Thinning was carried out with

removal of central strands and shortening of terminal tips with different intensities and

combination of both. For the removal of central strands, firstly these were counted from

each selected bunch for performing the required intensity of thinning. Whereas, for

shortening of terminal tips, the strands length was measured with a hand scale from

selected bunches and then the required intensity of thinning was executed as mentioned

above in the treatments layout.

3.3.2.2 Fruit harvesting

During the entire harvesting season, rutab/ripe fruits were periodically collected from the

selected bunches and weighed. Fruits showing soft brownish tip were considered as ripe

or rutab fruits. From each replication 100 rutab fruits were randomly selected for physical

and biochemical analysis.

38

Performing thinning operation Removal of central strands

Removal of terminal tips Tagging of thinned bunches

Slide-3.4: Performing strands thinning practices at early kimri stage

39

3.3.3 Ripening and quality assessment of date palm fruit by the influence of hot

water treatment.

The experiment was comprised of five treatments under completely randomized design

(factorial) with three replications and two date palm cultivars ‘Hillawi and ‘Khadrawi’.

The treatments detail is given as under.

T1: Control T4: HWD at 65oC for 5 min

T2: HWD at 65oC for 1 min T5: HWD at 65

oC for 7 min

T3: HWD at 65oC for 3 min

3.3.3.1 Fruit collection and hot water treatments procedure

The fruit was collected at khalal stage from Post Graduate Agricultural Research Station,

Institute of Horticultural Sciences, University of Agriculture Faisalabad, Pakistan. The

collected fruits along with strands were brought to the laboratory for further procedure.

After cleaning and washing, fruits of both cultivars (Hillawi and Khadrawi) were dipped

in hot water at a fixed temperature of 65oC but timing was ascending to the treatments.

The treated samples were placed under ambient conditions (25 ± 4oC, 70-75% R.H.) for

ripening until the fruit reached at tamer stage. From each replication 100 tamar fruits

were randomly selected for physical and biochemical analysis.

3.3.4 Effects of different chemicals on the ripening behaviour and fruit quality of

date palm.

The experiment was comprised of nine treatments under completely randomized design

(factorial) with three replications and two date palm cultivars ‘Hillawi and ‘Khadrawi’.

The treatments detail is given below.

T1: Control (without chemical dipping)

T2: Dipping in 2% acetic acid solution

T3: Dipping in 3% acetic acid solution

T4: Dipping in 2% NaCl solution

T5: Dipping in 3% NaCl solution

T6: Dipping in 2 ml/L ethephon solution

T7: Dipping in 4 ml/L ethephon solution

T8: Dipping in 2% acetic acid+2% NaCl+2 ml/L ethephon solution

T9: Dipping in 3% acetic acid+3% NaCl+4 ml/L ethephon solution

3.3.4.1 Fruit collection and treatments procedure

The fruits were collected at khalal stage from Post Graduate Agricultural Research

Station, Institute of Horticultural Sciences, University of Agriculture Faisalabad,

40

Pakistan. The collected fruits were brought to the laboratory for further procedure. After

cleaning and washing fruits were immersed in the aforementioned chemicals solutions for

4 to 5 minutes at ambient temperature (25 ± 4oC, 70-75% R.H.) and then incubated in an

aerated incubator at 40 ± 1oC for 72 h (Chakraverty et al., 2003). After incubation 100

tamar fruits were randomly selected for physical and biochemical analysis.

3.3.5 Sun-drying techniques (SDTs) affected the fruit quality attributes of dates

picked at rutab stage cv. Hillawi.

The experiment was comprised of five treatments under completely randomized design

with three replications (5 kg fruit per replication) in Hillawi date palm cultivar. The

treatments detail is given below.

SDT1: Control (DSE without covering and removal during night)

SDT2: DSE on mat and covered with polythene sheet during night

SDT3: DSE on mat and removal in baskets during night

SDT4: DSE on mat with removal in baskets and covered during night

SDT5: DSE on mat and removal with mats during night

3.3.5.1 Fruit collection and treatments procedure

The fruit of Hillawi cultivar was harvested at rutab stage from Post Graduate Agricultural

Research Station, Institute of Horticultural Sciences, University of Agriculture

Faisalabad, Pakistan (Latitude 31o-26´ N, Longitude 73

o-06´ E and Altitude 184.4 m).

The collected fruit was dried under direct sun light exposure (DSE) by adopting different

sun drying techniques (SDTs). The sun drying practices were carried out continuously for

6 to 8 days (depends on daily temperature) until fruit goes to <25% moisture level. From

each replication 100 tamar fruits were randomly selected for biochemical analysis.

3.4 Detail of field work (observations recorded)

The detail of all collected data during the research work is given as under.

3.4.1 External/physical observations recorded:

All the external/physical parameters were collected randomly from the tagged fruit

bunches/experimental units. The following parameters were recorded:

3.4.1.1 Time taken to reach the fruit at final kimri stage (days)

Time taken to reach the fruit at final kimri stage (full hard green fruit) after the treatments

application was recorded from tagged bunches and then average was calculated.

3.4.1.2 Time taken to reach the fruit at final khalal stage (days)

Time taken to reach the fruit at khalal stage (yellow fruit) after the treatments application

was recorded from the tagged bunches and then average was calculated.

41

3.4.1.3 Time taken to reach the fruit at rutab stage (days)

Time taken to reach the fruit at rutab stage (fruit showing soft/brown tip portion) after the

treatments applications were recorded from the tagged bunches of each treatment and

then average was calculated.

3.4.1.4 Time taken to reach the fruit at tamar stage (days)

Time taken to reach the fruit at tamar stage after the treatments application was recorded

from the tagged experimental units and then average was calculated.

3.4.1.5 Rutab fruit yield per bunch (kg)

Rutab fruit yield per bunch was calculated from tagged bunches with a digital weighing

balance during the entire harvesting season and then average was calculated. Fruit tips

showing soft/brown portion are considered as rutab/ripe fruits.

3.4.1.6 Uniform fruit ripening index (%)

Uniform fruit ripening index was calculated by using the following formula as given

below.

Uniform fruit ripening index (%) = X/Y×100

Where,

X = Number of ripe fruits Y = Total number of fruits

3.4.1.7 Fruit weight (g)

For fruit weight, thirty fruits were randomly selected from each replication and weighed

with digital balance and then average of individual fruit was calculated.

3.4.1.8 Fruit length (mm)

The fruit length of thirty selected fruits was recorded with a digital vernier calliper and

then average of individual fruit length was calculated.

3.4.1.9 Fruit width (mm)

The fruit width of thirty selected fruits was recorded with a digital vernier calliper and

then average of individual fruit width was calculated.

3.4.1.10 Fruit flesh weight (g)

For calculating the flesh weight, cut thirty selected fruits with a knife and remove the

stone then weighed with digital balance and calculate the mean value.

3.4.1.11 Fruit stone weight (g)

After removing the flesh from thirty selected fruits, stone weight was measured with a

digital balance and then average was calculated.

42

3.4.1.12 Fruit weight loss (%)

For the determination of fruit weight loss, fruits were weighed before imposing the

treatments which served as the initial fruit weight. The loss in weight was recorded at the

final day of observation which served as the final fruit weight. The loss in weight was

determined by the following formula and expressed as percentage.

Fruit weight loss = Initial fruit weight – Fruit weight at final observation × 100

Initial fruit weight

3.4.2 Biochemical analysis

3.4.2.1 Moisture determination (%)

Moisture percentage was determined by an automatic electronic computer operated

moisture tester (Brabender® MT-C, made by GmbH & Co. KG, Germany).

3.4.2.2 Total soluble solids concentration (oBrix)

Total soluble solids concentration was measured by using digital refractometer (ATAGO,

RX-5000, Japan) at room temperature (20oC) and readings were expressed as

oBrix.

3.4.2.3 Ascorbic acid (mg 100 g-1

)

Ascorbic acid contents were determined following the method described by Ruck (1961)

by titrating the extracted juice samples against 2, 6-dichlorophenolindophenol dye, to

light pink color end point, persisted at least for 15 seconds. The vitamin-C was calculated

by using following formula as given below.

Ascorbic acid / Vit. C (mg 100 g-1

) = 1 × R1 × V × 100

R × W × V1

R: ml of dye used to titrate against 2.5 ml (1 ml standard ascorbic acid + 1.5 ml 0.4%

oxalic acid) of reference solution (standard reading)

R1: ml of dye used to titrate against V1 of aliquot (sample reading)

V: Volume of the aliquot made by 0.4% oxalic acid

V1: ml of juice taken for titration

W: ml of aliquot used for titration

Dye was prepared by adding 42 mg NaHCO3 and 52 mg 2, 6-dichlorophenol indophenols

in a 200 ml volumetric flask. Volume was made up to the mark by adding distilled water.

It was filtered and used as freshly prepared dye.

3.4.2.4 Total titratable acidity (%)

Total titratable acidity (TA) was determined by the method described by Hortwitz (1960)

by titrating the extracted juice samples against 0.1N NaOH, using 2-3 drops of

phenolphthalein as an indicator till pink color end point was achieved. Total acidity was

measured according to the following formula:

43

Total titratable acidity (%) = 0.1N NaOH used × 0.0064 × 100

ml of juice taken for titration

3.4.2.5 Total tannins

Total tannins contents were estimated according to the method of (AOAC, 1980) by

titrating the extracted fruit samples with standard potassium permanganate solution by

using indigo caramine as in indicator until colour changed to faint pink and values were

expressed as percentage.

3.4.2.6 Total phenolics

Total phenolic contents (TPC) were calculated by using Folin-Ciocalteu reagent method

as reported by Ainsworth and Gillespie (2007). The FC-reagent (10 mL) was dissolved in

distilled water to make the solution 100 mL. In each sample (100 mL), FC-reagent (200

μL) was added and vortex thoroughly. The 700 mM Na2CO3 (800 μL) was added into

each sample and incubated at room temperature for 2 h. Sample (200 μL) was transferred

to a clear 96-well plate and absorbance of each well was measured at 765 nm. Amount of

TPC was calculated using a calibration curve for Gallic acid. The results were expressed

as Gallic acid equivalent.

3.4.2.7 Total antioxidants

Total antioxidants activity of the date fruits (skin+pulp) was assessed by measuring their

scavenging abilities to 2, 2-diphenyl-1-picrylhydrazyl stable radicals as described by

Amira et al. (2012). The absorbance was read against blank at 517 nm using micro-plate

ELISA reader (BioTek, USA). Inhibition of free radical by DPPH in percent was

calculated by following formula:

I % = (Ablank -Asample /Ablank) × 100

Where Ablank is the absorbance of the control reaction mixture excluding fruit sample, and

Asample is the absorbance of the test compounds. IC50 values, which represented the

concentration of date fruit extracts that caused 50% neutralization of DPPH radicals, were

calculated from the plot of inhibition percentage against concentrations.

3.4.2.8 Total flavonoids

Flavonoids were determined by the method of Kim et al. (2003). Distilled water (4 ml)

was added to 1 ml of extracted aliquot. Then, 5% sodium nitrite solution (0.3 ml) was

added, followed by 10% aluminum chloride solution (0.3 ml). Test tubes were incubated

at ambient temperature for 5 min, and then 2 ml of 1M sodium hydroxide were added to

the mixture and then the volume of reaction mixture was made up to 10 ml with distilled

water. The mixture was thoroughly vortex and the absorbance of the pink colour

44

developed was determined in a UV-visible spectrophotometer (IRMECO, U2020-

Germany) at 510 nm. A calibration curve was prepared with catechin and the results were

expressed as mg catechin equivalents. All the measurements were taken in triplicate and

the mean values were calculated.

3.4.2.9 Estimation of sugars through HPLC

For the estimation of sugars date fruit was extracted from the date flesh (2 g) in HPLC

grade ethanol (80% v/v). The available extracts were then centrifuged at 13000 xg for 10

min and then supernatants were separated and analysed by high performance liquid

chromatography (HPLC).

Liquid chromatographic (LC) separation was carried out at room temperature on a Razex

RCM-Monosaccharide Ca+2, Phenomenex column with flow rate of 0.60 ml/min at 80oC.

The mobile phase was 100% double distilled water (DDH2O). The HPLC was connected

to a refractive index detector (ReID) RID-10 AL (Shimadzu, Japan) having the range of

(bipolar, 1250 mV,) with peak width of 0.200 min. Identified sugars were quantified on

the basis of peak areas of external standards consisting of glucose (1%), fructose (1%)

and sucrose (1%) solutions. Reducing sugars were calculated as a sum of glucose and

fructose values and total sugars were calculated by sum of glucose, fructose and sucrose.

Each sample was carried out from integrated peak areas of the sample against the

corresponding standard graph. Results were expressed as percentage of fresh weight.

3.4.3 Organoleptic evaluation

Organoleptic evaluation of the fruit for color, taste, texture, astringency, firmness and

overall acceptability was performed using the 5 point hedonic scale. Five master level

students were chosen from the Institute of Horticultural Sciences, as panelists who were

asked to mark the following parameters by using the 5 point hedonic scale:

Product: _____________ Variety: __________________ Date: ________________

Name of Judge:_________________________ Signature: _______________________

Please follow the numerical system for scoring the samples.

Very poor ---------------1 Good -------------------- 4

Poor ----------------------2 Excellent-----------------5

Satisfactory-------------- 3

Please do not disturb the sequence of the samples provided.

Please wash the tongue before testing next sample, with water provided.

45

Table 3.1 Organoleptic evaluation of Hillawi and Khadrawi date palm cultivars.

Sample

No.

Colour Taste Texture Astringency Firmness Overall

acceptability

1

2

3

4

5

3.5 Statistical analysis

The collected data were statistically analyzed using computer software MSTAT-C.

Analysis of variance was used to test the significance of variance. While difference

among treatment means were compared using LSD test (p = 0.05) (Steel et al., 1997).

Figure 3.1 Average meteorological data during two seasons (2011-2012) at

experimental site of date palm orchard.

0

20

40

60

80

100

120

140

Feb March April May June July August

Rela

tive h

um

idit

y (

%)

RH Temp Sunshine Wind speed Total Rain fall

46

Chapter-4 RESULTS AND DISCUSSION

4.1a Study-1 Evaluating the potential of ethephon on ripening acceleration and

fruit quality of date palm at kimri stage.

4.1.1a Results

4.1.1.1a Fruit maturity/ripening traits

4.1.1.1.1a Time taken to reach the fruit at late khalal stage (days)

Statistically significant differences (p ≤ 0.05) were found regarding the effects of

ethephon treatments and cultivars while interaction between them showed non-significant

results for time taken to reach the fruit at khalal stage (Figure 4.1a). Higher

concentrations of ethephon (spray and injection) accelerate the fruit maturity period two-

fold as compared to lower doses of ethephon in both date palm cultivars. The fruits those

were sprayed with ethephon @ 6 ml/L and 4 ml/L took shorter time (15.25 and 16.25

days) to complete the period from final kimri to late khalal stage, respectively and these

were statistically at par with each other. Whereas, more time of 27.50 days were noted in

the untreated fruits to complete the period from final kimri to late khalal stage. The fruits

of Hillawi cultivar took shorter time of 19.76 days to accomplish the period from final

kimri to late khalal stage as compared to the fruits of Khadrawi where more time of 22.92

days were noted to complete that period. Meanwhile, fruits those were sprayed with

ethephon @ 2 ml/L and by injection @ 3 ml/bunch showed intermediate effect in

accelerating the fruit maturity period (time taken to reach the fruit at late khalal stage) of

both date palm cultivars.

4.1.1.1.2a Time taken to reach the fruit at rutab stage (days)

The analyzed data presented in Figure 4.2a showed significant differences at p ≤ 0.05

regarding the effects of ethephon treatments and cultivars while their interaction was

found non-significant for time taken to reach the fruit at rutab stage. Higher

concentrations of ethephon (spray and injection) speed up the process of fruit maturity

two-fold than lower doses of ethephon in both date palm cultivars. The fruits those were

sprayed with ethephon @ 6 ml/L took shorter time of 32.83 to complete the period from

final kimri to rutab stage followed by fruits those were sprayed with ethephon @ 4 ml/L.

Whereas, more time of 47.66 and 46.25 days were recorded in the fruit those were

untreated and by ethephon injection @ 1 ml/bunch, respectively to complete the period

from final kimri to rutab stage and these were at par with each other. The fruits of Hillawi

47

cultivar took shorter time of 38.59 days to accomplish the period from final kimri to rutab

stage as compared to the fruits of Khadrawi where 41.35 days were noted to complete that

period. In the meanwhile, fruits sprayed with ethephon @ 2 ml/L and by injection @ 3

ml, 2 ml/bunch showed intermediate effect on time taken to reach the fruit at rutab stage


4.1.1.1.3a Rutab fruit yield per bunch (kg)

Rutab fruit yield per bunch showed significant differences at p ≤ 0.05 regarding the

effects of ethephon treatments and cultivars while interaction between them was found

non-significant (Figure 4.3a). The increased concentration of ethephon also increased the

rutab fruit yield per bunch in both cultivars. Higher rutab fruit yield of 7.78 kg per bunch

was recorded in the fruits those were sprayed with ethephon @ 6 ml/L followed by fruits

those were sprayed with ethephon @ 4 ml/L. While, minimum rutab fruit yield of 1.91,

2.13 and 2.47 kg per bunch was noted in the fruits those were untreated and by injection

@ 1ml and 2ml/bunch, respectively and these were at par with each other. More rutab

fruit yield (4.43 kg) per bunch was noted in Hillawi cultivar as compared to the fruits of

Khadrawi where rutab fruit yield of 3.31 kg per bunch was recorded. Similarly, fruits

sprayed with ethephon @ 2 ml/L and by injection @ 3 ml, 2 ml/bunch showed

intermediary effect on rutab fruit yield of both date palm cultivars.

4.1.1.1.4a Uniform fruit ripening index (%)

Statistically significant differences were found at p ≤ 0.05 regarding the effects of


results for uniform fruit ripening index (Figure 4.4a). The rate of uniform fruit ripening

increased as well as the concentration of ethephon increased. Fruits those were sprayed

with ethephon @ 6 ml/L and 4 ml/L showed higher uniform fruit ripening indexes of

62.35 and 60.46%, respectively and these were statistically at par with each other. While,

lower uniform fruit ripening index of 34.14% was recorded in the untreated fruits and

these were at par with the fruits those were treated with ethephon injection @ 1 ml/bunch

where uniform fruit ripening index was 35.24%. The Hillawi fruits attained higher

uniform fruit ripening index of 50.01% as compared to the fruits of Khadrawi where fruit

ripening index of 44.75% was measured. The in

termediate effect was observed in fruits those were sprayed with ethephon @ 2 ml/L and

by injection @ 3 ml, 2 ml/bunch regarding the uniform fruit ripening of both date palm

cultivars.

48

Figure 4.1a Effects of different ethephon concentrations (spray and injection) on

time taken (days) from final kimri to late khalal stage of Hillawi and



time taken (days) from final kimri to rutab stage of Hillawi and


0

5

10

15

20

25

30

35

Control 2ml/L 4ml/L 6ml/L 1ml/bunch 2ml/bunch 3ml/bunch

Foliar spray Injection

Tim

e t

ak

en

to

kh

ala

l st

ag

e (

da

ys)

Hillawi Khadrawi

0

10

20

30

40

50

60



Tim

e t

ak

en

to

ru

tab

sta

ge (

da

ys)

Hillawi Khadrawi

49


rutab fruit yield per bunch (kg) of Hillawi and Khadrawi date palm

fruit ± S.E.


uniform fruit ripening index (%) of Hillawi and Khadrawi date palm

fruits ± S.E.

0

1

2

3

4

5

6

7

8

9



Ru

tab

yie

ld p

er b

un

ch

(k

g)

Hillawi Khadrawi

0

10

20

30

40

50

60

70

80



Un

iform

fru

it r

ipen

ing

in

dex

(%

)

Hillawi Khadrawi

50

4.1.1.2a Fruit physical traits

4.1.1.2.1a Fruit weight (g)

Statistically non-significant differences were found at p ≥ 0.05 regarding the effects of

ethephon treatments and interaction while both cultivars showed significant results for

fruit weight (Figure 4.5a). The fruits of Hillawi attained higher weight (7.19 g) as

compared to fruits of Khadrawi where fruit weight of 6.32 g was recorded.

4.1.1.2.2a Fruit length (mm)

The analyzed data presented in Figure 4.6a showed non-significant differences (p ≥ 0.05)

regarding the effects of ethephon treatments and interaction while both cultivars differ

significantly for fruit length. Regarding the response of cultivars, Hillawi fruits attained

maximum length (36.52 mm) than the fruits of Khadrawi where fruit length of 32.56 mm

was noted.

4.1.1.2.3a Fruit width (mm)

Effects of ethephon treatments and interaction were found non-significant (p ≥ 0.05)

while both cultivars showed significant results for fruit width (Figure 4.7a). The fruits of

Khadrawi cultivar attained higher width (22.50 mm) as compared to the fruits of Hillawi

where fruit width of 18.52 mm was noted.

4.1.1.2.4a Fruit flesh weight (g)

Statistically non-significant differences (p ≥ 0.05) were found regarding the effects of


fruit flesh weight (Figure 4.8a). The fruits of Hillawi attained higher flesh weight (6.17 g)

than the fruits of Khadrawi where flesh weight of 5.62 g was recorded.

4.1.1.2.5a Fruit pit weight (g)

Fruit pit weight showed non-significant differences at p ≥ 0.05 regarding the effects of

ethephon treatments and interaction while a significant differences was found in cultivars

(Figure 4.9a). The fruits of Hillawi attained higher pit weight (1.02 g) as compared to the

fruits of Khadrawi where pit weight of 0.69 g was measured.

51


fruit weight (g) of Hillawi and Khadrawi date palm ± S.E.


fruit length (mm) of Hillawi and Khadrawi date palm ± S.E.

4

4.5

5

5.5

6

6.5

7

7.5

8



Fru

it w

eig

ht

(g)

Hillawi Khadrawi

30

32

34

36

38

40



Fru

it l

en

gth

(m

m)

Hillawi Khadrawi

52


fruit width (mm) of Hillawi and Khadrawi date palm ± S.E.


flesh weight (g) of Hillawi and Khadrawi date palm fruit ± S.E.

10

12

14

16

18

20

22

24



Fru

it w

idth

(m

m)

Hillawi Khadrawi

5

5.2

5.4

5.6

5.8

6

6.2

6.4

6.6

6.8

7



Fru

it f

lesh

weig

ht

(g)

Hillawi Khadrawi

53


pit weight (g) of Hillawi and Khadrawi date palm fruit ± S.E.

4.1.1.3a Fruit biochemical traits

4.1.1.3.1a Fruit moisture content (%)

The analyzed data presented in Figure 4.10a showed statistically significant differences (p

≤ 0.05) regarding the effects of ethephon treatments, cultivars and their interaction for

fruit moisture content. The progression of ripening decreased the fruit moisture contents.

Higher ethephon concentrations showed more reduction in fruit moisture content as

compared to lower concentrations in both cultivars. Lower level of moisture content

36.48% was noted in the fruit of Hillawi those were sprayed with ethephon @ 6 ml/L

followed by fruits sprayed with ethephon @ 4 ml/L. Whereas, higher level of moisture

content (39.50 and 39.22%) was recorded in the untreated fruits and those were treated

with ethephon injection @ 1 ml/bunch and these were statistically similar to each other.

The fruits of Hillawi showed lower level of moisture content (37.86%) than the fruits of

Khadrawi where moisture contents of 38.72% were noted. The fruits those were sprayed

with ethephon @ 2 ml/L and by injection @ 3 ml/bunch showed intermediate effect

regarding the fruit moisture content of both date palm cultivars.

4.1.1.3.2a Total soluble solids concentration (oBrix)

Total soluble solids concentration in fruit showed significant differences (p ≤ 0.05)

regarding the effects of ethephon treatments and cultivars while interaction between them

0

0.2

0.4

0.6

0.8

1

1.2



Hillawi Khadrawi

54

was found non-significant (Figure 4.11a). Total soluble solids increased positively with

the progression of fruit ripening. The fruits those were sprayed with ethephon @ 4 ml/L

showed higher amount of total soluble solids contents (9.45 oBrix) followed by fruits

sprayed with ethephon @ 6 ml/L. While, lower amount of TSS contents of 7.87 and 8.04

oBrix were noted in untreated fruits and these were at par with the fruits those were

treated with ethephon injection @ 1 ml/bunch where TSS contents were 8.04 oBrix.

Hillawi fruits showed higher amounts of TSS contents (9.08 oBrix) as compared to the

fruits of Khadrawi where TSS contents of 8.37 oBrix were recorded. The intermediary

effect on TSS contents was noted in fruits those were sprayed with ethephon @ 2 ml/L

and by injection @ 3 ml/bunch in both date palm cultivars.

4.1.1.3.3a Total titratable acidity (%)


ethephon treatments and cultivars while their interaction showed non-significant results

for total titratable acidity (Figure 4.12a). Lower levels of total titratable acidity (0.174,

0.203 and 0.213%) were recorded in the fruits those were sprayed with ethephon @ 4, 6

and 2 ml/L and these were statistically similar to each other. Whereas, higher levels of

total titratable acidity (0.287%) was noted in the untreated fruits and these were at par

with the fruits those were treated with ethephon injection @ 1ml/bunch, 2ml/bunch and

3ml/bunch where titratable acidity values were 0.276, 0.256 and 0.246%, respectively and

these were at par with each other. Hillawi fruits showed lower level of titratable acidity

(0.207%) as compared to the fruits of Khadrawi where titratable acidity of 0.266% was

recorded.

4.1.1.3.4a Ascorbic acid (mg 100 g-1

)

The analyzed data presented in Figure 4.13a showed significant differences at p ≤ 0.05


was found non-significant for ascorbic acid. Higher ascorbic acid contents (1.39 and 1.29

mg 100 g-1

) were recorded in the fruits those were sprayed with ethephon @ 4 ml/L, 6

ml/L. While, lower amounts of ascorbic acid of 0.94 mg 100 g-1

were noted in control

fruits and these were at par with the fruits those were treated with ethephon injection @ 1

ml/bunch where level of ascorbic acid values was 1.01 mg 100 g-1

recorded. The Hillawi

fruits showed higher amounts of ascorbic acid (1.21 mg 100 g-1

) as compared to the fruits

of Khadrawi where ascorbic acid contents of 1.12 mg 100 g-1

were noted. The fruits those

were sprayed with ethephon @ 2 ml/L and by injection @ 3 and 2 ml/bunch showed

intermediate effect regarding ascorbic acid in both date palm cultivars.

55


fruit moisture content (%) of Hillawi and Khadrawi date palm fruit

± S.E.


total soluble solids concentration (oBrix) of Hillawi and Khadrawi


30

32

34

36

38

40

42



Mo

istu

re c

on

ten

t (%

)

Hillawi Khadrawi

0

2

4

6

8

10

12



TS

S (

oB

rix

)

Hillawi Khadrawi

56

Figure 4.12a Effects of different ethephon concentrations (spray and injection)


fruit ± S.E.




fruit ± S.E.

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35



Acid

ity

(%

)

Hillawi Khadrawi

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8



Asc

orb

ic a

cid

(m

g 1

00

g-1

)

Hillawi Khadrawi

57

4.1.1.3.5a Glucose (%)

The analyzed data presented in Figure 4.14a showed significant differences regarding the

effects of ethephon treatments and cultivars while interaction between them was found

non-significant for glucose. Higher levels of glucose (23.32, 22.81 and 22.40%) were

noted in fruits those were sprayed with ethephon @ 4 ml/L, 6 ml/L and 2 ml/L and these

were at par with each other. While, lower amounts of glucose (18.25%) were recorded in

fruits those were untreated and these were at par with the fruits those were treated with

ethephon injection @ 1 ml/bunch where glucose of 18.52% were noted. The fruits of

Hillawi showed higher glucose contents (21.96%) as compared to the fruits of Khadrawi

where glucose of 20.20% was noted. Fruits treated with ethephon injection @ 3 ml/bunch

showed intermediate effect regarding glucose of both date palm cultivars.

4.1.1.3.6a Fructose (%)



results for fructose (Figure 4.15a). Higher fructose contents (21.65 and 21.19%) were

recorded in fruits those were sprayed with ethephon @ 4 ml/L and 6 ml/L, respectively

and these were at par with each other. Whereas, lower level of fructose (17.08%) were

noted in fruits those were untreated and these were at par with the fruits those were

treated with ethephon injection @ 1 ml/bunch. Hillawi fruits showed higher amounts of

fructose contents (20.24%) than the fruits of Khadrawi where fructose of 19.06% were

recorded. Fruits those were sprayed with ethephon @ 2 ml/L and by injection @ 3

ml/bunch showed intermediary effect regarding the fructose on both date palm cultivars.

4.1.1.3.7a Sucrose (%)

Effects of ethephon treatments and cultivars showed significant differences (p ≤ 0.05)

while interaction between them were found non-significant regarding the sucrose (Figure

4.16a). Fruits those were sprayed with ethephon @ 4 ml/L and 6 ml/L showed higher

level of fructose (5.81 and 5.52%), respectively and these were at par with each other.

While, fruits those were untreated showed lower value of sucrose of 3.99%. The fruits of

Hillawi attained higher level of sucrose (5.21%) as compared to the fruits of Khadrawi

where sucrose of 4.55% was noted. The intermediate effect was recorded in fruits those

were sprayed with ethephon @ 2 ml/L and by injection @ 3 ml/bunch regarding the

fructose in both cultivars.

58

4.1.1.3.8a Reducing sugars (%)

Statistically significant differences (p≤0.05) were found regarding the effects of ethephon

treatments and cultivars while their interaction showed non-significant results for

reducing sugars (Figure 4.17a). Fruits those were treated with foliar spray @ 4 ml/L, 6

ml/L and 2 ml/L achieved higher values of reducing sugars (44.97, 44.00 and 43.47%),

respectively and these were at par with each other. Whereas, lower level of reducing

sugar contents (35.33%) were recorded in untreated fruits and these were at par with the

fruits those were treated with ethephon injection @ 1 ml/bunch where reducing sugars of

35.75% were noted. The fruits of Hillawi showed higher amounts of reducing sugars

(42.20%) than the fruits of Khadrawi where reducing sugars of 39.27% were recorded.

Meanwhile, fruits those were treated with ethephon injection @ 3 ml/bunch showed

intermediate effect on reducing sugars of both date palm cultivars.

4.1.1.3.9a Total sugars (%)

The analyzed data presented in Figure 4.18a showed significant differences at p≤0.05


was found non-significant for total sugars. The fruits those were sprayed with ethephon

@ 4 ml/L and 6 ml/L showed higher levels of total sugars of 50.78 and 49.52%,

respectively and these were at par with each other. While, fruits those were untreated

showed lower level of total sugars (39.32%) and these were at par with the fruits those

were treated with ethephon injection @ 1 ml/bunch where total sugars of 40.07% were

noted. Hillawi fruits attained higher level of total sugars (47.42%) as compared to the

fruits of Khadrawi where total sugars of 43.82% were recorded. The intermediary effect

regarding total sugars was noted in fruits those were sprayed with ethephon @ 2 ml/L and

by injection @ 3 ml/bunch in both date palm cultivars.

59





0

5

10

15

20

25

30



Glu

co

se (

%)

Hillawi Khadrawi

0

5

10

15

20

25



Fru

cto

se (

%)

Hillawi Khadrawi

60




on reducing sugars (%) of Hillawi and Khadrawi date palm fruit ±

S.E.

0

1

2

3

4

5

6

7



Su

cro

se (

%)

Hillawi Khadrawi

0

10

20

30

40

50

60



Red

ucin

g s

ug

ars

(%)

Hillawi Khadrawi

61


on total sugars (%) of Hillawi and Khadrawi date palm fruit ± S.E.

4.1.1.4a Fruit phytonutritional traits

4.1.1.4.1a Total phenolics (mg GAE/100 g)

Total phenolics in the fruits at rutab stage showed significant differences (p ≤ 0.05)


was found non-significant (Figure 4.19a). Fruits those were sprayed with ethephon @ 4

ml/L and 6 ml/L showed higher amounts of total phenolics (158.72 and 152.50 mg

GAE/100 g), respectively and these were at par with each other. While, fruits those were

untreated showed lower amounts of total phenolics (116.57 mg GAE/100 g) and these

were at par with the fruits those were treated with ethephon injection @ 1 ml/bunch

where total phenolics of 121.71 mg GAE/100 g were noted. The fruits of Khadrawi

attained higher amounts of total phenolics (141.35 mg GAE/100 g) as compared to the

fruits of Hillawi where total phenolics of 132.37 mg GAE/100 g were recorded. The fruits

those were sprayed with ethephon @ 2 ml/L and by injection @ 3 ml/bunch showed

intermediate effect regarding the total phenolics in both date palm cultivars.

4.1.1.4.2a Total flavonoids (mg CEQ/100 g)



results for total flavonoids in fruit at rutab stage (Figure 4.20a). Higher amounts of total

flavonoids (49.51 mg CEQ/100 g) were recorded in fruits those were sprayed with

0

10

20

30

40

50

60



To

tal

sug

ars

(%)

Hillawi Khadrawi

62

ethephon @ 4 ml/L. While, lower amounts of total flavonoids (21.29 mg CEQ/100 g)

were noted in control fruits and these were at par with the fruits those treated with

ethephon injection @ 1 ml/bunch and 2 ml/bunch where values of total flavonoids were

21.70 and 22.78 mg CEQ/100 g, respectively and these were at par with each other. The

Hillawi fruits attained higher amounts of total flavonoids (33.79 mg CEQ/100 g) as

compared to the fruits of Khadrawi where total flavonoids of 30.02 mg CEQ/100 g were

noted. The intermediate effect regarding the total flavonoids was observed in fruits those

were sprayed with ethephon @ 6, 2 ml/L and by injection @ 3 ml/bunch in both date

palm cultivars.

4.1.1.4.3a Total tannins (%)

The analyzed data presented in Figure 4.21a showed statistically significant differences (p

≤ 0.05) for total tannins regarding the effects of ethephon treatments and cultivars while

interaction between them was found non-significant. The fruit those were sprayed with

ethephon @ 4 ml/L and 6 ml/L showed lower levels of total tannins (0.48 and 0.52%) and

these were at par with each other. Whereas, higher amounts of total tannins (0.87%) were

noted in fruits those were untreated and these were at par with the fruits those were

treated with ethephon injection @ 1 ml/bunch where total tannins were 0.84%. The fruits

of Hillawi showed lower amounts of total tannins (0.63%) than the fruits of Khadrawi

where total tannin contents of 0.73% were recorded. The fruits those were sprayed with

ethephon @ 2 ml/L and by injection @ 3 ml/bunch showed intermediate effect regarding

the total tannins in both dates palm cultivars.

4.1.1.4.4a Total antioxidants (%)



results for total antioxidants activities in fruits at rutab stage (Figure 4.22a). Higher total

antioxidants activities of 61.79 and 59.78% were recorded in fruits those were sprayed

with ethephon @ 4 ml/L and 6 ml/L, respectively and these were at par with each other.

Whereas, lower total antioxidants activities (40.20%) were noted in untreated fruits and

these were at par with the fruits those were treated with ethephon injection @ 1 ml/bunch

where total antioxidants activities of 42.49% were recorded. The fruits of Khadrawi

showed higher total antioxidants activities (51.49%) as compared to the fruits of Hillawi

where total antioxidants activities of 48.16% were noted. The intermediary effect

regarding the total antioxidants activities was noted in fruits those were sprayed with

ethephon @ 2 ml/L and by injection @ 3, 2 ml/bunch in both date palm cultivars.

63



palm fruit ± S.E.


on total flavonoids (mg CEQ/100 g) of Hillawi and Khadrawi date

palm fruit ± S.E.

0

20

40

60

80

100

120

140

160

180



TP

C (

mg

GA

E/1

00

g)

Hillawi Khadrawi

0

10

20

30

40

50

60



TF

C (

mg

CE

Q/1

00

g)

Hillawi Khadrawi

64


on total tannins (%) of Hillawi and Khadrawi date palm fruit ± S.E.


on total antioxidants (%) of Hillawi and Khadrawi date palm fruits

± S.E.

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1



To

tal

tan

nin

s (%

)

Hillawi Khadrawi

0

10

20

30

40

50

60

70



To

tal

an

tio

xid

an

ts (

%)

Hillawi Khadrawi

65

4.1b Study-1 Effectiveness of ethephon on the ripening acceleration

and physico-chemical characteristics of date palm at

khalal stage.

4.1.1b Results

4.1.1.1b Fruit maturity/ripening traits

4.1.1.1.1b Time taken to reach the fruit at late khalal stage (days)



results for time taken to reach the fruit at late khalal stage (Figure 4.23b ). Fruits those

were sprayed with ethephon @ 4 ml/L and 2 ml/L took shorter time of 9.25 and 11.58

days to complete the period from early khalal to late khalal stage, respectively and these

were statistically similar to each other. Whereas, fruits those were untreated took more

time (16.41 days) to accomplish that period and these were at par with the fruits those

were treated with ethephon injection @ 1 ml/bunch, 2 ml/bunch and 3 ml/bunch those

took 15.00, 14.75 and 14.50 days to complete the period from early khalal to late khalal

stage, respectively. The fruits of Hillawi completed the period in shorter time of 12.57

days as compared to the fruits of Khadrawi those took 14.19 days to accomplish the

period from early khalal to late khalal stage. The fruits those were sprayed with ethephon

@ 6 ml/L showed intermediate effect regarding the time taken to reach the fruit at late

khalal stage in both date palm cultivars.

4.1.1.1.2b Time taken to reach the fruit at rutab stage (days)

The analyzed data presented in Figure 4.24b showed statistically significant differences


was found non-significant for time taken to reach the fruit at rutab stage. The fruits those

were sprayed with ethephon @ 4 ml/L took shorter time of 15.91 days to complete the

period from early khalal to rutab stage. While, fruits those were untreated took more time

of 26.41 days to accomplish the period from early khalal to rutab stage. The Hillawi fruits

completed the period from early khalal to rutab stage in shorter time (19.40 days) than the

fruits of Khadrawi those took 22.64 days to accomplish that period. The intermediary

effect was observed in fruits those were sprayed with ethephon @ 2 ml/L, 6 ml/L and by

injection @ 3 ml/bunch regarding the time taken to reach the fruit at rutab stage in both


66

4.1.1.1.3b Rutab fruit yield per bunch (kg)


ethephon treatments and cultivars while their interaction showed non-significant results

for rutab fruit yield per bunch (Figure 4.25b). Ethephon treatments effectively increased

the rutab fruit yield per bunch as compared to control fruits in both date palm cultivars.

Higher rutab fruit yield (4.91 and 4.37 kg) per bunch was recorded in fruits those were

sprayed with ethephon @ 4 ml/L and 2 ml/L, respectively and these were at par with each

other. Whereas, lower rutab fruit yield of 1.67 kg per bunch was noted in untreated fruits

and these were at par with the fruits those were treated with ethephon injection @ 1

ml/bunch and 2 ml/bunch where rutab fruit yield was 1.86 and 1.96 kg per bunch,

respectively. Hillawi fruits attained more rutab fruits yield (3.27 kg) per bunch as

compared to the fruits of Khadrawi where rutab fruit yield of 2.49 kg per bunch was

noted. The fruits those were sprayed with ethephon @ 6 ml/L and by injection @ 3

ml/bunch showed intermediate effect on rutab fruit yield per bunch in both date palm

cultivars.

4.1.1.1.4b Uniform fruit ripening index (%)

Uniform fruit ripening index showed statistically significant differences at p ≤ 0.05


was found non-significant (Figure 4.26b). Ethephon treatments significantly increased the

uniform fruit ripening index as compared to the fruits those were untreated in both

cultivars. Maximum uniform fruit ripening indexes of 46.65 and 44.85% were noted in

fruits those were sprayed with ethephon @ 4 ml/L and 2 ml/L, respectively and these

were at par with each other. Whereas, minimum uniform fruit ripening index of 31.62%

was recorded in control fruits and these were at par with the fruits those were treated with

ethephon injection @ 1 ml/bunch, 2 ml/bunch and 3 ml/bunch where uniform fruit

ripening indexes were 31.90, 32.61 and 36.08%, respectively. The fruits of Hillawi

showed higher uniform fruit ripening index (39.46%) than the fruits of Khadrawi where

uniform fruit ripening index of 35.48% was recorded. The fruits those were sprayed with

ethephon @ 6 ml/L showed intermediate effect regarding the uniform fruit ripening index


67

Figure 4.23b Effects of different ethephon concentrations (spray and injection)

on time taken (days) from early khalal to late khalal stage of



on time taken (days) from early khalal to rutab stage of Hillawi and


0

2

4

6

8

10

12

14

16

18

20



Tim

e t

o l

ate

kh

ala

l st

ag

e (

da

ys)

Hillawi Khadrawi

0

5

10

15

20

25

30



Tim

e t

o l

ate

ru

tab

stg

ae (

da

ys)

Hillawi Khadrawi

68



palm fruit ± S.E.


on uniform fruit ripening index (%) of Hillawi and Khadrawi date

palm fruit ± S.E.

0

10

20

30

40

50

60



Ru

tab

fru

it y

ield

bu

nch

-1 (

kg

)

Hillawi Khadrawi

0

1

2

3

4

5

6

7



Un

ifo

rm

fru

it r

ipen

ing

in

dex (

%)

Hillawi Khadrawi

69

4.1.1.2b Fruit physical traits

4.1.1.2.1b Individual fruit weight (g)


ethephon treatments and interaction while both cultivars differ significantly (4.27b). The

fruits of Hillawi cultivar attained maximum weight (7.35 g) as compared to the fruits of

Khadrawi where weight of 6.27 g was noted.

4.1.1.2.2b Fruit length (mm)

Effects of ethephon treatments and interaction showed non-significant differences (p ≥

0.05) while a significant difference were found in cultivars regarding the fruit length at

rutab stage (Figure 4.28b). Hillawi fruits achieved greater length (36.22 mm) than the

fruits of Khadrawi where fruit length of 32.36 mm was recorded.

4.1.1.2.3b Fruit width (mm)

The analyzed data presented in Figure 4.29b showed non-significant differences at p ≥

0.05 regarding the effects of ethephon treatments and interaction while a significant

difference was found in cultivars. The fruits of Khadrawi attained higher fruit width

(22.42 mm) as compared to the fruits of Hillawi where width of 18.46 mm was recorded.

4.1.1.2.4b Fruit flesh weight (g)

Fruit flesh weight at rutab stage showed non-significant differences (p ≥ 0.05) regarding

the effects of ethephon treatments and interaction while a significant difference was found

in cultivars (4.30b). Hillawi fruits showed higher flesh weight (6.41 g) than the fruits of

Khadrawi where flesh weight of 5.51 g was recorded.

4.1.1.2.5b Fruit pit weight (g)


ethephon treatments and interaction while cultivars showed significant results for fruit pit

weight at rutab stage (Figure 4.31b). The fruits of Hillawi attained higher pit weight (0.94

g) as compared to the fruits of Khadrawi where pit weight of 0.76 g was noted.

70


on individual fruit weight (g) of Hillawi and Khadrawi date palm ±

S.E.



1

2

3

4

5

6

7

8



Fru

it w

eig

ht

(g)

Hillawi Khadrawi

0

5

10

15

20

25

30

35

40



Fru

it l

en

gth

(m

m)

Hillawi Khadrawi

71




on fruit flesh weight (g) of Hillawi and Khadrawi date palm fruit ±

S.E.

0

5

10

15

20

25



Fru

it w

idth

(m

m)

Hillawi Khadrawi

1

2

3

4

5

6

7



Fru

it f

lesh

weig

ht

(g)

Hillawi Khadrawi

72



4.1.1.3b Fruit biochemical traits

4.1.1.3.1b Fruit moisture content (%)

The analyzed data presented in Figure 4.32b showed statistically significant differences (p

≤ 0.05) regarding the effects of ethephon treatments and cultivars while interaction

between them was found non-significant for moisture content in fruit at rutab stage. The

moisture content decreased positively as well as the fruit goes to ripening. Fruits those

were sprayed with ethephon @ 4 ml/L and 2 ml/L showed lower levels of moisture

contents (35.22 and 36.01%), respectively and these were at par with each other.

Whereas, fruits those were untreated showed higher value of moisture content (37.64%)


ml/bunch where moisture content of 37.14% in fruits were noted. The fruits of Hillawi

attained lower level of moisture content (36.08%) than the fruit of Khadrawi where

moisture contents of 37.00% were noted. The fruits those were sprayed with ethephon @

6 ml/L and by injection @ 3 ml/bunch showed intermediary effect on fruit moisture

content of both date palm cultivars.

4.1.1.3.2b Total soluble solids concentration (oBrix)



0

0.2

0.4

0.6

0.8

1

1.2



Fru

it p

it w

eig

ht

(g)

Hillawi Khadrawi

73

results for total soluble solids in fruits at rutab stage (Figure 4.33b). Total soluble solids

increased positively with the progression of ripening. Higher doses of ethephon at khalal

stage decreased the level of TSS as compared to lower doses. Higher total soluble solids

of 8.03 and 7.55 oBrix were noted in fruits those were sprayed with ethephon @ 2 ml/L

and 4 ml/L, respectively and these were at par with each other. While, lower amounts of

total soluble solids (6.75 oBrix) were noted in untreated fruits and these were at par with

the fruits those were treated with ethephon injection @ 1ml/bunch, 2 ml/bunch and 3

ml/bunch and sprayed @ 6 ml/L where TSS values were 6.86, 6.90, 7.06 and 7.22 oBrix,

respectively and these were at par with each other. The Hillawi fruits attained higher total

soluble solids (7.57 oBrix) as compared to the fruits of Khadrawi where total soluble

solids of 6.81 oBrix were recorded.

4.1.1.3.3b Total titratable acidity (%)

The effects of ethephon treatments and cultivars were found significant (p ≤ 0.05) while

interaction between them showed non-significant results for total titratable acidity in

fruits at rutab stage (Figure 4.34b). The fruits those were sprayed with ethephon @ 2 ml/L

and 4 ml/L showed lower values of total titratable acidity (0.180 and 0.207%) and these

were at par with the fruits those were treated with ethephon injection @ 3 ml/bunch

where titratable acidity of 0.221% was recorded. Whereas, higher total titratable acidity

values (0.296%) were noted in control fruits and these were at par with the fruits those

were treated with ethephon injection @ 1 ml/bunch where total titratable acidity of

0.273% was recorded. The Hillawi fruits showed lower value of total titratable acidity

(0.213%) than the fruits of Khadrawi where total titratable acidity of 0.260% was noted.

The fruit sprayed with ethephon @ 6 ml/L and by injection @ 2 ml/bunch showed

intermediate effect regarding the total titratable acidity of both date palm cultivars.

4.1.1.3.4b Ascorbic acid (mg 100 g-1

)

The analyzed data presented in Figure 4.35b showed significant differences (p ≤ 0.05)


was found non-significant for ascorbic acid in fruit at rutab stage. Higher ascorbic acid

(1.43 and 1.32 mg 100 g-1

) was recorded in the fruits those were sprayed with ethephon

@ 2 ml/L and 4 ml/L, respectively and these were at par with each other. While, lower

ascorbic acid (1.00 mg 100 g-1

) were noted in untreated fruit and these were at par with

ethephon injection @ 1 ml, 2 ml, 3 ml/bunch and by spray @ 6 ml/L. The Hillawi fruits

attained higher ascorbic acid (1.29 mg 100 g-1

) as compared to the fruit of Khadrawi

where ascorbic acid contents of 1.06 mg 100 g-1

were noted.

74


on moisture content (%) of Hillawi and Khadrawi date palm fruit ±

S.E.




32

33

34

35

36

37

38

39



Mo

istu

re c

on

ten

t (%

)

Hillawi Khadrawi

0

1

2

3

4

5

6

7

8

9

10



TS

S (

oB

rix

)

Hillawi Khadrawi

75



fruit ± S.E.




fruit ± S.E.

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4



Acid

ity

(%

)

Hillawi Khadrawi

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8



Asc

orb

ic a

cid

(m

g 1

00

g-1

)

Hillawi Khadrawi

76

4.1.1.3.5b Glucose (%)


ethephon treatments and interaction while both cultivars differ significantly for glucose in

fruit at rutab stage (Figure 4.36b). The application of ethephon (spray and injection) at

khalal stage did not show any response regarding the glucose in fruit of both cultivars.

The fruit of Hillawi showed higher level of glucose (20.70%) as compared to the fruit of

Khadrawi where glucose of 18.73% was recorded.

4.1.1.3.6b Fructose (%)

Fructose in fruit at rutab stage showed non-significant differences at p ≥ 0.05 regarding


in cultivars (Figure 4.37b). The application of ethephon (spray and injection) at khalal

stage did not show any positive effect on fructose in fruit of both cultivars. Hillawi fruit

achieved higher amounts of fructose (19.65%) than the fruits of Khadrawi where fructose

of 17.61% was noted.

4.1.1.3.7b Sucrose (%)

The analyzed data presented in Figure 4.38b showed statistically non-significant results (p

≥ 0.05) regarding the effects of ethephon treatments and interaction while a significant

difference was found in sucrose of both cultivars. The application of ethephon (spray and

injection) at khalal stage did not show any response regarding the sucrose in fruits of both

cultivars. The fruits of Hillawi attained higher amounts of sucrose (3.85%) than the fruits

of Khadrawi where sucrose of 2.93% was noted.

4.1.1.3.8b Reducing sugars (%)



reducing sugars in fruit at rutab stage (Figure 4.39b). The application of ethephon (spray

and injection) at khalal stage did not show any response regarding the reducing sugars in

fruit of both cultivars. The Hillawi fruit achieved higher level of reducing sugars

(40.36%) as compared to the fruit of Khadrawi where reducing sugars of 36.34% were

noted.

4.1.1.3.9b Total sugars (%)

Total sugars in fruit at rutab stage showed non-significant differences (p ≥ 0.05) regarding


in cultivars (Figure 4.40b). The application of ethephon (spray and injection) at khalal

stage did not show any response regarding the total sugars in fruit of both cultivars.

77

Hillawi fruit attained higher amounts of total sugars (43.98%) as compared to the fruit of

Khadrawi where total sugars of 38.80% were noted.





0

5

10

15

20

25



Glu

co

se (

%)

Hillawi Khadrawi

0

5

10

15

20

25



Fru

cto

se (

%)

Hillawi Khadrawi

78




on reducing sugars (%) of Hillawi and Khadrawi date palm fruit ±

S.E.

0

1

2

3

4

5



Su

cro

se (

%)

Hillawi Khadrawi

0

10

20

30

40

50



Red

ucin

g s

ug

ar (

%)

Hillawi Khadrawi

79


on total sugars (%) of Hillawi and Khadrawi date palm fruit ± S.E.

4.1.1.4b Fruit phytonutritional traits

4.1.1.4.1b Total phenolics (mg GAE/100 g)

Total phenolics in fruit measured at rutab stage showed significant differences (p ≤ 0.05)


was found non-significant (Figure 4.41b). Ethephon application (spray and injection) at

khalal stage positively improved the total phenolic contents as compared to untreated fruit

of both date palm cultivars. Higher amounts of total phenolics (146.36, 143.74 and 136.43

mg GAE/100 g) were noted in fruit those treated with ethephon spray @ 2 ml/L, 4 ml/L

and 6 ml/L, respectively and these were at par with each other. Whereas, lower amounts

of total phenolics of 112.99 mg GAE/100 g were recorded in fruit those were untreated

and these were at par with the fruit those were treated with ethephon injection @ 1

ml/bunch and 2 ml/bunch where total phenolics of 114.97 and 119.39 mg GAE/100 g,

respectively were noted. The fruit of Khadrawi attained higher amounts of total phenolics

(133.87 mg GAE/100 g) as compared to the fruit of Khadrawi where total phenolics of

122.66 mg GAE/100 g were recorded.

4.1.1.4.2b Total flavonoids (mg CEQ/100 g)


ethephon treatments and interaction while cultivars showed significant results for total

0

10

20

30

40

50



To

tal

sug

ar (

%)

Hillawi Khadrawi

80

flavonoids in fruit at rutab stage (Figure 4.42b). The application of ethephon (spray and

injection) at khalal stage did not show any response regarding the total flavonoids in fruit

of both date palm cultivars. The Hillawi fruit showed higher amounts of total flavonoids

contents (44.11 mg CEQ/100 g) as compared to the fruit of Khadrawi where total

flavonoids contents of 38.82 mg CEQ/100 g were noted.

4.1.1.4.3b Total tannins (%)

The analyzed data presented in Figure 4.43b showed significant differences at p ≤ 0.05

regarding the effects of ethephon treatments and cultivars while their interaction was

found non-significant for total tannins in fruit at rutab stage. Total tannins decreased

significantly with the progression of fruit ripening. The fruit sprayed with ethephon @ 2

ml/L and 4 ml/L showed lower levels of total tannins (0.515 and 0.546 %), respectively

and these were at par with each other. Whereas, higher amounts of total tannins of 0.897

and 0.810% were noted in fruits those were untreated and by injection @ 1 ml/bunch,

respectively and these were at par with each other. Hillawi fruits attained lower amounts

of total tannins (0.607%) than the fruit of Khadrawi where total tannins of 0.776% were

recorded. The fruits those were sprayed with ethephon @ 6 ml/L and by injection @ 3

ml/bunch showed intermediary effect on total tannins of both date palm cultivars.

4.1.1.4.4b Total antioxidants (%)

Total antioxidants activities in fruit at rutab stage showed statistically significant

differences (p ≤ 0.05) regarding the effects of ethephon treatments and cultivars while

interaction between them was found non-significant (Figure 4.44b). Higher total

antioxidants activities of 55.73 and 52.35% were noted in fruits those were sprayed with

ethephon @ 2 ml/L and 4 ml/L, respectively and these were at par with each other.

Whereas, lower total antioxidants activities of 45.92% were recorded in untreated fruits


ml/bunch, 2 ml/bunch, 3 ml/bunch and by foliar spray @ 6 ml/L where total antioxidants

activities of 46.33, 47.06, 47.67 and 47.86%, respectively and these were at par with each

other. The fruit of Khadrawi showed higher total antioxidants activities (51.66%) as

compared to the fruit of Hillawi where total antioxidants activities of 46.31% were

recorded.

81



palm fruit ± S.E.


on total flavonoids (mg CEQ/100 g) of Hillawi and Khadrawi date

palm fruit ± S.E.

0

20

40

60

80

100

120

140

160

180



TP

C (

mg

GA

E/1

00

g)

Hillawi Khadrawi

0

10

20

30

40

50

60



TF

C (

mg

CE

Q/1

00

g)

Hillawi Khadrawi

82


on total tannins (%) of Hillawi and Khadrawi date palm fruit ± S.E.


on total antioxidants (%) of Hillawi and Khadrawi date palm fruit

± S.E.

0

0.2

0.4

0.6

0.8

1

1.2



To

tal

tan

nin

s (%

)

Hillawi Khadrawi

0

10

20

30

40

50

60

70



To

tal

an

tio

xid

an

ts (

%)

Hillawi Khadrawi

83

4.1.2 (a, b) Discussion

Monsoon rains at the time of fruit harvesting and/or ripening are extremely harmful and

causes heavy fruit loss in the form of rotting, fruit drop and uneven ripening and quality.

Present study therefore, was started to investigate the effects of ethephon (foliar and

injection) at final kimri and early khalal stages on the ripening acceleration and fruit

quality of Hillawi and Khadrawi date palm cultivars. Fruit maturation from final kimri to

rutab and early khalal to rutab stages indicated that application of ethephon (spray and

injection) played an important role to shorten the fruit transition period, however foliar

spray performed better as compared to injection application in both cultivars date palm

cultivars. This reduction in fruit transition period might be due to the influence of

ethylene which was released by the application of ethephon and hasten the fruit ripening

process. It is because ethylene is hydrolyzed in plant tissues (Cooke and Randall, 1968;

Warner and Leopold, 1967) and accelerates the physiological process of maturation in

fruits (Liberman, 1979). It is also reported that ethephon regulates many aspects of fruit

ripening (Szyjewicz et al., 1984; Abeles et al., 1992) and is considered as the hormone of

fruit maturation (Hartmann, 1992) as it promotes the degradation of chlorophyll that

alters the fruit texture and internal quality characters (Worku et al., 1975; Lopez et al.,

2000). Ethephon application at early fruit maturation phases accelerate the fruit ripening

processes to breakdown the cell wall which leads to tissue softening in apples (Curry,

1994). Ethephon fasten up the level of ripeness in grapevines (Han et al., 1996; Nikolaou

et al., 2003; Delgado et al., 2004), apples (Jones, 1979) and Rabbit eye blueberry (Ban et

al., 2007).

Foliar spray of ethephon applied at both fruit maturity stages (final kimri and early khalal)

gave better results as compared to injection application in both date palm cultivars.

However, ethephon application at final kimri stage was more effective as compared to

early khalal stage in both cultivars. Foliar spray of ethephon (6 ml/L and 4 ml/L) at final

kimri stage accelerated the fruit ripening period by about two weeks from final kimri to

rutab stage. Meanwhile, foliar spray of ethephon (4 ml/L and 2 ml/L) at early khalal stage

accelerated the ripening period by about 6 days form early khalal to rutab stage. Our

results are confirmed with Mougheith and Hassaballa (1979) who reported that pre-

harvest ethephon application speed up the fruit maturation period in ‘Hayany’ date palm.

These findings are also correlated with Kamal (1995) who reported that foliar application

of ethephon hasten the fruit ripening about one month in ‘Zaghloul’ and ‘Samani’ date

84

palm cultivars. Musa (2001) reported that application of ethephon accelerated the fruit

ripening period two to three folds in ‘Mishrigi Wad Khatib’ and ‘Mishrigi Wad Lagi’ date

palm cultivars. This effect of ethephon is also reported in other fruit crops such as in ber

(Zizyphus mauritiana L.) foliar application of ethephon accelerated the fruit ripening

period about 2 weeks (Bal et al., 1996), 13 to 22 days in persimmon (Kim et al., 2004)

and 8 days in fig fruits (Puech et al., 1976).

The fruit of date palm do not ripe uniformly on the tree and required more number of

pickings which ultimately increases the labor cost and is too expensive. Regarding the

effectiveness of ethephon on uniform fruit ripening in date palm, rare literature is

available. In our study foliar application of ethephon significantly increased the rutab fruit

yield per bunch and produced more uniformly ripe fruits as compared to untreated fruits

in both cultivars. More rutab fruit yield per bunch and higher uniform fruit ripening index

were noted in fruits treated with foliar spray @ 6 ml/L and 4 ml/L at final kimri and early

khalal fruit stages, respectively. The increase in rutab fruit yield per bunch and uniform

fruit ripening index were mainly due to the action of ethylene that generates from

ethephon. These findings are correlates with Ed Peter (2009) who reported that pre-

harvest spray of ethephon resulted in earlier fruit maturation and higher uniformity in

ripening with good quality composition in grapes, strawberry and cranberry fruits. These

findings are also correlated with Awad (2007) who reported that higher rutab fruit yield

per bunch or evenly ripe fruits were obtained from ethephon treated fruits in ‘Hilali’ date

palm as compared to untreated fruits. He also reported that no significant difference was

found between the foliar and injection application methods. However, in the present study

method of application showed a great variation in their response as foliar spray performed

better as compared to injection method. It is because foliar spray might have a direct

contact with fruits cuticle layer that fasten up the respiration process and fruits reached at

maturity within shorter time. Whereas, ethephon application by injection could not

showed quick and fast response due to its slow translocation from the peduncle to

individual fruit strands. It might also be possible that the whole amount of ethephon

concentrations used could not reach in proper way to the desired place.

The current findings regarding the fruit physical traits (fruit weight, fruit length, fruit

width, fruit flesh weight, fruit pit weight) showed statistically non-significant (p ≥ 0.05)

differences against ethephon application while both date palm cultivars differ

significantly. The difference in cultivars might be due to the genetic character that

responds differently to fruit physical traits.

85

Fruit moisture content is an important feature of fruit quality. Application of ethephon at

final kimri and early khalal fruit stages significantly decreased the moisture contents in

fruits of Hillawi and Khadrawi cultivars. More reduction in fruit moisture contents were

noted in fruits treated with foliar spray as compared to injection application. Foliar spray

@ 6 ml/L and 4 ml/L at final kimri and early khalal fruit stages showed more reduction in

moisture contents of both cultivars, respectively. This decline in fruit moisture contents

might be due to the progression of ripening process due the action of ethylene. The

findings of Frenkel and Hartman (2012) support our results; they reported that water

contents in potato tubers and tomato fruit were lower down due to the action of ethylene

that stimulated the onset of ripening processes, suggesting that a relationship exist

between decreased water contents and onset of ripening. They concluded that the decline

in tissue water contents induced by ethylene is strongly correlated with a decrease in

hydration efficacy of cell wall that might account for changes in tissue water contents.

Maximum total soluble solids contents in treated fruits especially where ethephon was

applied by foliar spray in both date palm cultivars during both years. It is because the

starch hydrolyzed into sugar during the progression of ripening and higher sugar contents

were noted at advanced stage of maturity or ripening (rutab). Fruit treated with foliar

spray (4 ml/L and 2 ml/L) at final kimri and early khalal stages attained higher TSS

contents in both cultivars, respectively. This increase in TSS in ethephon-treated fruits

might be due to the rise of sugar contents which depends upon the conversion of starch on

hydrolysis or it might be due to the enhanced ripening initiated by the ethylene. These

results are confirmed with the findings of (Khalifa et al., 1975; Rouhani and Bassiri,

1977) who reported that pre-harvest ethephon application efficiently improved the total

soluble solid contents in date fruits than the untreated fruits. These results were later

confirmed by (Mougheith and Hassaballa (1979; Shamshiri and Rahemi, 1999) who

reported that pre-harvest application of ethephon noticeably increased the TSS in

‘Hayany’ and Mazafati date palm cultivars. Ben-yehoshua et al. (1970) and Mougheith

and El-Banna (1974) also found similar results regarding the total soluble solids in fig

fruits. According to Sandhu et al. (1989) foliar spray of ethephon in ber (Ziziphus

mauritiana L.) fruits significantly increased the amount of total soluble solids as

compared to fruits where no ethephon was applied. Pre-harvest spray of ethephon

increased the TSS contents in table grapes (Nikolaou et al., 2003) and ‘Cripp’s Pink’

apple (Whale et al., 2008) at the time of commercial fruit harvest.

86

In ethephon treated fruits, acidity level was decreased as compared to untreated fruits.

More reduction in fruits acidity was recorded in foliar spray of ethephon as compared to

injection application. Foliar application of ethephon @ 4 ml/L and 2 ml/L at final kimri

and early fruit stages significantly decreased the level of fruit acidity, respectively. The

reduction in fruit acidity might be due to the effect of ethylene on the activity of enzymes

that promotes the fruit ripening process and lower down the acidity level (Sisler, 1984;

McGlasson, 1985; Yang, 1985). Our findings are also in line with Hashinaga and Itoo

(1985) who reported that ethephon application significantly reduced the acidity level in

‘Meiwa Kumquat’ fruits. Foliar spray of ethephon @ 4 ml/L and 2 ml/L at final kimri and

early khalal stages increased the ascorbic acid contents in treated fruits as compared to

control fruits. This is because ethephon treated fruits reached at maturity or ripening in

shorter time and fruits have less time to loss the ascorbic acid contents. These findings are

supported by various co-workers who reported that ethephon application increased the

ascorbic acid contents in different fruit crops such as cape gooseberry (Yadava et al.

2008), mango (Mann, 1985) and ‘Allahabad Safeda’ guava cultivar (Brar et al., 2012).

In the present study ethephon treatments at final kimri stage significantly increased the

accumulation of sugar contents in treated fruits while non-significant differences were

found when ethephon was applied at early khalal stage. Foliar spray of ethephon @ 4

ml/L at final kimri stage produced higher sugar contents (glucose, fructose, sucrose) as

compared to injection application in both cultivars. These results are in line with (Bal et

al., 1996; Gala et al., 2001; Singh et al., 2001; Suresh and Singh, 2003; Kulkarni et al.,

2004) they all reported that ethephon treatments significantly improved the sugar contents

in different fruits as compared to untreated fruits. The rise in sugar contents might also be

due to the onset of ripening process. However, in date fruit, no evidence is reported in the

literature which ensures that ethephon application increased the sugars contents.

Ethephon application at final kimri stage had a significant influence on the

phytonutritional composition in both date palm cultivars. More accumulation of

phytonutrients was observed in fruits treated with foliar spray as compared to injection

application. Foliar spray of ethephon @ 4 ml/L at final kimri stage showed higher amount

of total phenolics, total flavonoids and total antioxidants with lower level of total tannin

contents. However, ethephon application at early khalal stage did not show significant

variation except reduction of total tannin contents in the ethephon-treated fruit. Our

results are correlates with the findings of Lin et al. (2009) they reported that application

of ethephon generates the ethylene that plays an important role for the synthesis of

87

phenolic compounds. These findings correlates with Whale et al. (2008) who reported

that pre-harvest ethephon application significantly increased the level of phenolics and

flavonoids due to the increased concentration of cyaniding 3-galactoside in the exposed

fruit skin at commercial harvest as compared to untreated fruits. It has also been reported

that, ethephon application increased the activity of PAL in the fruit skin of apples

(Larrigaudiere et al., 1996; Li et al., 2002). A transitory exposure to ethylene can trigger

or enhance the activity of anthocyanin biosynthetic pathway (Wang and Dilley, 2001;

Awad and de Jager, 2002). Liu et al., (2013) reported that ethylene released from

ethephon significantly increased the total phenolic contents and antioxidants activities.

This increase in total phenolics might be due to the increased activity of glucose-6P

dehydrogenase (G6PDH) enzyme by the application of ethephon. Guaiacol peroxidase

(GPX) is the enzyme which is responsible for polymerization of phenolic compounds.

Higher concentration of ethephon significantly increased the GPX activity (Liu et al.,

2013). According to El-Kereamy et al. (2000) ethephon treatments enhanced the gene

expression of some enzymes that advanced the synthesis of phenolic compounds. It is

also reported that ethylene exposure in asparagus promoted the metabolism of

phenylpropanoind that leads to the accumulation of phenolic compounds and tissue

lignification (Lipton, 1990). The increase in antioxidants activities of both date palm

cultivars treated with ethephon demonstrated an increase in their nutritional value.

Ethephon treatments also build up the level of total flavonoids contents. These results are

also supported by different workers (Nikolaou et al., 2003; Lombard et al., 2004; El-

Kereamy et al., 2000); they all reported that pre-harvest ethephon application produced

higher contents of total polyphenols, flavonoids and proanthocyanidins in table grapes. In

our study total tannin contents were also decreased in fruits subjected to ethephon

treatments as compared to untreated fruits. These results are associated with the findings

of (Kato, 1990; Itamura et al., 1991; Taira et al., 1991; Park et al., 1998; Tamura et al.,

1999) they reported that higher concentration of ethephon greatly accelerated the

coagulation process of tannins in persimmon fruits due to the disappearance of

astringency and fruits become sweeter in taste. This reduction in fruit astringency might

be due to the coagulation of tannin cells into insoluble tannins.

The results of current study have an important commercial implication as pre harvest

ethephon application at final kimri stage effectively accelerated the fruit ripening period

and also improved the fruit quality composition in date palm. Foliar spray of ethephon @

4 ml/L at final kimri stage proved as the most effective to accelerate the fruit ripening

88

period by about 13 days with good fruit quality characters in both date palm cultivars.

However, ethephon application @ 2 ml/L at early khalal stage also accelerated the fruit

ripening period about 6 days but fruit quality is least affected at this stage of maturity in

both cultivars. Accelerating the fruit ripening period or shortening the period of about two

weeks between final kimri to rutab stage, growers can harvest the fruit earlier (13 days)

before the onset of peak monsoon rains. For this purpose pesticide companies should be

involved to commercialize this ethylene releasing chemical. Nonetheless, more research

is needed to investigate the response of ethephon on other commercial date palm

cultivars. The present research work suggests that more attention should be given to use

the ethephon as foliar spray at final kimri fruit maturity stage on commercial scale or at

farm level.

4.1.3 (a, b) Conclusion

In conclusion, pre-harvest spray of ethephon (4 ml/L) at final kimri stage is effective to

accelerate the fruit maturation period about 13 days, attained uniformity index of 60.46%,

rutab fruit yield (6.29 kg) per bunch and also improved the fruit quality composition in

terms of total soluble solids concentration, ascorbic acid, sugars, total phenolics, total

flavonoids and total antioxidants with decreased levels of acidity and total tannins in both

date palm cultivars. Whereas, foliar application of ethephon (2 ml/L) at early khalal stage

also accelerate the fruit maturity period about 6 days, attained uniformity index of

44.85% and rutab fruit yield (4.37 kg) per bunch while fruit quality composition is least

affected at this stage of fruit maturity in both Hillawi and Khadrawi cultivars. In

conclusion, foliar application of ethephon (4 ml/L) at final kimri stage is an effective

cultural practice to accelerate the fruit maturity period and to combat the seasonal

fluctuations in the form of monsoon rains at the time of fruit harvesting and/or ripening of

both tested date palm cultivars.

89

4.2 Study-2 Exploring the role of thinning practices on the ripening

acceleration and fruit quality of date palm

4.2.1 Results

4.2.1.1 Fruit maturity/ripening traits

4.2.1.1.1 Time taken from early kimri to final kimri stage (days)

The presented data demonstrated that strands thinning treatments and cultivars showed

significant differences (p ≤ 0.05) regarding the time taken to reach final kimri stage while

their interaction effect was found non-significant (Table 4.1). Strands thinning treatments

significantly reduced the degree days and reached the fruits earlier at maturity as

compared to fruits where no thinning was practiced. Thinning intensity @ 30% RCS +

30% STT took shorter time (95.83 days) to complete the period from early kimri to late

kimri stage that was statistically at par with thinning intensity @ 30% RCS alone which

took 97.00 days to accomplish that period. More time (107.50 days) to accomplish this

period was recorded in fruits those were without thinning treatments (control) (Table 4.1).

The fruits of Hillawi cultivar took shorter time (99.55 days) to reach from early kimri to

late kimri stage than the fruits of Khadrawi which took 102.81 days. The fruits those were

treated with thinning intensity @ 20% RCS alone and in combination with 20%

RCS+20% STT tended to have an intermediate effect regarding time taken from early

kimri to final kimri stage in both date palm cultivars.

4.2.1.1.2 Time taken from early kimri to late khalal stage (days)

Effects of strands thinning treatments and cultivars showed statistically significant

differences (p ≤ 0.05) while their interaction did not differ significantly regarding the time

taken to reach the fruit from early kimri to khalal stage (Table 4.2). Strands thinning

treatments significantly reduced the period from early kimri to late khalal stage by the

fruits as compared to no thinning treatments (control fruits). Thinning intensity @ 30%

RCS alone took shorter time of 123.25 days to complete the period from early kimri to

late khalal stage by the fruits that was statistically at par with thinning degree at the

combination of 30% RCS + 30% STT as compared to other thinning treatments.

However, maximum time (133.67 days) was noted in fruits to accomplish this period

where no thinning treatments were practiced and that was at par with thinning intensity @

20% SST alone which took 133.08 days to complete that period in both date palm

cultivars (Table 4.2). Hillawi fruits took shorter times of 126.62 days to complete the

90

period from early kimri to late khalal stage than Khadrawi fruits those took 129.69 days.

Meanwhile, strands thinning @ 20% RCS alone and in combination with 20% RCS+20%

SST showed intermediary effect on time taken from early kimri to late khalal stage of


4.2.1.1.3 Time taken from early kimri to rutab stage (days)

Statistical analysis showed that strands thinning treatments and cultivars differ

significantly at p ≤ 0.05 while interaction between cultivars and treatments was found

non-significant regarding time taken from early kimri to rutab stage by the fruits (Table

4.3). Thinning treatments significantly shortened the fruit transition period from early

kimri to rutab stage as compared to control fruits (no thinning). Thinning intensity @

30% RCS alone took minimum degree days (141.75 days ) to complete the period from

early kimri to rutab stage that was at par with thinning degree at combination of 30%

RCS + 30% STT which took 141.83 days to complete that period. Whereas, fruits with no

thinning treatments took 152.58 days to accomplish this period and these were

statistically similar to thinning intensity @ 20% STT and 30% STT alone which took

152.00 and 151.58 days to complete that period (Table 4.3). Fruits of Hillawi took shorter

time (144.31days) to complete the period from early kimri to rutab stage as compared to

the fruits of Khadrawi cultivar those took 149.24 days to reach from early kimri to rutab

stage. In the meanwhile, the strands thinning intensity @ 20% RCS alone and in

combination with 20% RCS+20%STT showed intermediate effect to accelerate the fruit

maturity from early kimri to rutab stage of both date palm cultivars.

4.2.1.1.4 Rutab fruit yield per bunch (kg)

Rutab fruit yield per bunch was significantly affected by strand thinning treatments,

cultivars and their interaction in both date palm cultivars (Table 4.4). Thinning treatments

significantly increased the rutab fruit yield per bunch in both cultivars than those fruits

where no thinning was practiced. Thinning degree @ 30% RCS alone achieved higher

rutab fruit yield of 5.22 kg per bunch as compared to all other treatments. Minimum rutab

fruit yield (3.00 kg) per bunch was recorded in untreated fruits where no thinning was

practiced and these were at par with strands thinning @ 20% STT alone in both date palm

cultivars (Table 4.4). Regarding the response of both cultivars, Hillawi attained higher

rutab fruit yield of 4.25 kg per bunch as compared to Khadrawi where rutab fruit yield of

3.69 kg per bunch was recorded. The strands thinning intensity @ 20% RCS alone and in

combination of 20% RCS+20% STT tended to have an intermediary effect on rutab fruit

yield per bunch of both date palm cultivars.

91

4.5 Uniform fruit ripening index (%)

Effects of strands thinning treatments and cultivars showed statistically significant

differences (p ≤ 0.05) while interaction between cultivars and treatments did not differ

significantly regarding uniform fruit ripening index (Table 4.5). Thinning treatments by

different intensities produced more uniformly ripe fruits as compared to control fruits

where no thinning was practiced in both date palm cultivars. Degree of thinning @ 30%

RCS alone showed higher uniform fruit ripening index (76.28%) as compared to all other

treatments during both years. Minimum uniform fruit ripening indexes of 34.33 and

39.79% were recorded in untreated fruits (no thinning) of both cultivars during the both

study years (Table 4.5). Hillawi cultivar showed higher uniform fruit ripening indexes

(59.09 and 56.89%) than Khadrawi where uniform fruit ripening indexes were 53.24 and

52.45% during the both years, respectively.

Table 4.1 Effects of different strands thinning intensities on time taken (days)

from early kimri to late kimri stage of Hillawi and Khadrawi date palm

fruit.

Thinning treatments Time taken from early kimri to late kimri stage (days)

Hillawi Khadrawi Mean

No thinning 105.50 109.50 107.50 A

20% RCS 97.83 101.33 99.58 C

30% RCS 95.33 98.67 97.00 DE

20% STT 103.67 107.00 105.33 B

30% STT 103.00 106.00 104.50 B

20% RCS+20%STT 97.33 99.67 98.50 CD

30%RCS+30%STT 94.17 97.50 95.83 E

Mean 99.55 B 102.81 A

LSD values Treatments= 2.01, Varieties= 1.07, Interaction= ns

RCS= Removal of central strands, STT= Shortening of terminal tips

Means sharing same case letter for main effects and interaction, do not differ significantly

at 5% probability level.

92


from early kimri to late khalal stage of Hillawi and Khadrawi date palm

fruit.

Thinning treatments Time taken from early kimri to late khalal stage (days)


No thinning 131.67 135.67 133.67 A

20% RCS 123.50 126.33 124.92 C

30% RCS 121.83 124.67 123.25 D

20% STT 131.33 134.83 133.08 AB

30% STT 130.00 134.17 132.08 B

20% RCS+20%STT 124.50 126.83 125.67 C

30%RCS+30%STT 123.50 125.33 124.42 CD

Mean 126.62 B 129.69A

LSD (P ≤ 0.05) Treatments= 1.31, Varieties= 0.70, Interaction= ns





from early kimri to rutab stage of Hillawi and Khadrawi date palm

fruit.

Thinning treatments Time taken from early kimri to rutab stage (days)


No thinning 149.83 155.33 152.58 A

20% RCS 141.67 146.17 143.92 B

30% RCS 139.50 144.00 141.75 C

20% STT 149.33 154.67 152.00 A

30% STT 149.00 154.17 151.58 A

20% RCS+20%STT 140.83 146.67 143.75 B

30%RCS+30%STT 140.00 143.67 141.83 C

Mean 144.31 B 149.24 A





93

Table 4.4 Effects of different strands thinning intensities on rutab fruit yield (kg)

per bunch of Hillawi and Khadrawi date palm fruit.

Thinning treatments Rutab fruit yield per bunch (kg)


No thinning 3.11 hi 2.90 i 3.00 F

20% RCS 4.89 c 3.73 e 4.31 C

30% RCS 5.62 a 4.81 c 5.22 A

20% STT 3.19 gh 3.06 hi 3.12 EF

30% STT 3.37 fg 3.18 gh 3.28 E

20% RCS+20%STT 4.38 d 3.56 ef 3.97 D

30%RCS+30%STT 5.19 b 4.56 d 4.87 B

Mean 4.25 A 3.69 B

LSD (P ≤ 0.05) Treatments= 0.17, Varieties= 0.09, Interaction= 0.24




Table 4.5 Effects of different strands thinning intensities on uniform fruit

ripening index (%) of Hillawi and Khadrawi date palm fruit.

Thinning treatments Uniform fruit ripening index (%)


No thinning 39.33 34.79 37.06 E

20% RCS 64.44 59.99 62.21 C

30% RCS 80.42 72.14 76.28 A

20% STT 40.31 36.38 38.34 DE

30% STT 41.44 38.66 40.05 D

20% RCS+20%STT 64.27 58.89 61.58 C

30%RCS+30%STT 75.73 69.07 72.40 B

Mean 57.99 A 52.84 B





94

4.2.2.1 Fruit physical traits

4.2.2.1.1 Individual fruit weight (g)

Statistically significant differences were found for strands thinning treatments and

cultivars while their interaction did not differ significantly regarding individual fruit

weight at rutab stage (Table 4.6). Thinning treatments significantly increased the

individual fruit weight in both cultivars than those fruits where no thinning was practiced

during both years. A gradual increase in individual fruit weight was noted as thinning

intensity increased in both cultivars. Thinning degree at the combination of @ 30% RCS

+ 30% STT produced fruits with greater weight of 8.23 g that was statistically at par with

thinning intensity @ 30% RCS alone where fruit weight of 8.11 g was measured. Lower

individual fruit weight of 5.88 g was recorded in fruits where no thinning was performed

in both cultivars (Table 4.6). The fruits of Hillawi cultivar attained higher individual fruit

weight (7.82 g) as compared to the fruits of Khadrawi where fruit weight of 6.86 g was

measured. The strands thinning intensity @ 20% RCS alone and in combination with

20% RCS + 20%STT showed intermediary effect on individual fruit weight of both date

palm cultivars.

4.2.2.1.2 Fruit length (mm)

The analyzed data presented in Table 4.7 showed statistically significant differences for

strands thinning treatments and cultivars while their interaction was found non significant

regarding the fruit length at rutab stage. Thinning treatments significantly increased the

fruit length as compared to fruits of control (no thinning). A significant increase in fruit

lengths were observed in fruits subjected to higher degree of thinning in both cultivars.

Thinning intensity @ 30% RCS + 30% STT produced fruits with greater length of 34.53

mm and these were at par with the fruits where thinning intensity @ 30% RCS alone was

practiced with fruit length of 33.88 mm but it was greater than the fruits of all other

treatments. Minimum fruit length of 26.54 mm was noted in untreated fruits (no thinning)

of both date palm cultivars (Table 4.2.2.1.2). The fruits of Hillawi achieved greater fruit

length of 33.40 mm than the fruits of Khadrawi where fruit length of 28.03 mm was

recorded. In the meanwhile, the thinning intensity @ 20% RCS alone tended to have an

intermediate effect regarding the fruit length of both date palm cultivars.

4.2.2.1.3 Fruit width (mm)

The effects of strands thinning treatments, cultivars and their interaction were found

statistically significant regarding the fruit widths at rutab stage (Table 4.8). Thinning

treatments significantly increased the fruit width as compared to fruits where no thinning

95

was performed during both years. A gradual increase in fruit width was noted where

thinning was practiced at higher intensity than the fruits subjected to lower thinning

intensities. The interaction effect between thinning treatments and cultivars showed that

strands thinning @ 30% RCS alone produced fruits with greater width of 22.71 mm these

were statistically at par with fruit having thinning intensity @ 30% RCS + 30% STT

where fruit width of 22.32 mm was noted in Khadrawi cultivar. Whereas, minimum fruit

width of 17.10 mm was recorded in the fruits of Hillawi cultivar where no thinning was

practiced (Table 4.8). Meanwhile, regarding the response of cultivars, the fruits of

Khadrawi attained higher width of 20.78 mm than the fruits of Hillawi where fruit width

of 18.86 mm was measured. Similarly, strands thinning intensity @ 20% RCS alone and

in combination of 20% RCS + 20% STT showed intermediary effect on fruit width of


4.2.2.1.4 Fruit flesh weight (g)

The analyzed data presented in Table 4.9 indicated that strands thinning treatments and

cultivars showed statistically significant differences while their interaction was found

non-significant regarding fruit flesh weight at rutab stage. Strands thinning treatments

significantly increased the fruit flesh weight as compared to the fruits of no thinning

treatments. Strands thinning intensity @ 30% RCS + 30% STT produced fruits with

greater flesh weight of 7.38 g and these were at par with fruits treated with thinning

intensity @ 30% RCS alone where fruit flesh weight of 7.23 g was noted. Minimum fruit

flesh weight of 5.03 g was recorded in fruits with no thinning in both cultivars (Table

4.9). The Hillawi fruits attained higher fruit flesh weight (6.85 g) as compared to

Khadrawi fruits where flesh weight of 6.10 g was recorded. Meanwhile, the fruits with

thinning intensity @ 20% RCS alone tended to have an intermediate effect on fruit flesh

weight of both date palm cultivars.

4.2.2.1.5 Fruit pit weight (g)

Statistically non significant differences were found for strands thinning treatments and

interaction effect while both date palm cultivars differ significantly between each other

regarding the fruit pit weight at rutab stage (Table 4.10). Regarding the response of both

cultivars, greater fruit pit weight (0.97 g) was recorded in Hillawi as compared to

Khadrawi where fruit pit weight of 0.76 g was measured.

96

Table 4.6 Effects of different strands thinning intensities on individual fruit


Thinning treatments Individual fruit weight (g)


No thinning 6.32 5.45 5.88 F

20% RCS 8.29 7.31 7.80 C

30% RCS 8.66 7.57 8.11 AB

20% STT 6.92 6.05 6.49 E

30% STT 7.29 6.47 6.88 D

20% RCS+20%STT 8.47 7.49 7.98 BC

30%RCS+30%STT 8.77 7.69 8.23 A

Mean 7.82 A 6.86 B





Table 4.7 Effects of different strands thinning intensities on fruit length (mm) of


Thinning treatments Fruit length (mm)


No thinning 28.83 24.25 26.54 D

20% RCS 35.14 28.93 32.04 B

30% RCS 36.62 31.15 33.88 A

20% STT 29.79 25.19 27.49 C

30% STT 30.19 25.45 27.82 C

20% RCS+20%STT 35.81 29.56 32.69 B

30%RCS+30%STT 37.40 31.67 34.53 A

Mean 33.40 A 28.03 B





97

Table 4.8 Effects of different strand thinning intensities on fruit width (mm) of


Thinning treatments Fruit width (mm)


No thinning 17.10 g 18.54 e 17.82 E

20% RCS 19.56 cd 21.42 b 20.49 B

30% RCS 19.76 cd 22.71 a 21.23 A

20% STT 17.73 f 19.29 d 18.51 D

30% STT 18.18 ef 19.56 cd 18.87 C

20% RCS+20%STT 19.72 cd 21.63 b 20.67 B

30%RCS+30%STT 19.97 c 22.32 a 21.14 A

Mean 18.86 B 20.78 A





Table 4.9 Effects of different strands thinning intensities on fruit flesh weight (g)

of Hillawi and Khadrawi date palm fruit.

Thinning treatments Fruit flesh weight (g)


No thinning 5.38 4.67 5.03 F

20% RCS 7.27 6.51 6.89 C

30% RCS 7.65 6.81 7.23 AB

20% STT 5.97 5.35 5.66 E

30% STT 6.29 5.70 5.99 D

20% RCS+20%STT 7.53 6.72 7.13 B

30%RCS+30%STT 7.83 6.93 7.38 A

Mean 6.85 A 6.10 B





98

Table 4.10 Effects of different strands thinning intensities on fruit pit weight (g)


Thinning treatments Fruit pit weight (g)


No thinning 0.938 0.773 0.855

20% RCS 1.021 0.805 0.913

30% RCS 1.005 0.761 0.883

20% STT 0.950 0.705 0.827

30% STT 1.000 0.778 0.889

20% RCS+20%STT 0.933 0.763 0.848

30%RCS+30%STT 0.941 0.760 0.850

Mean 0.970 A 0.763 B

LSD (P ≤ 0.05) Treatments= ns, Varieties= 0.027, Interaction= ns




4.2.3.1 Fruit biochemical traits

4.2.3.1.1 Fruit moisture content (%)

The results presented in Table 4.11 illustrated that effects of strand thinning treatments

and cultivars were found statistically significant while their interaction did not differ

significantly regarding fruit moisture content at rutab stage. Fruit moisture decreased

progressively with the onset of fruit ripening. Thinning treatments significantly decreased

the level of moisture content in fruit as compared to non thinning fruits. Fruits thinned @

30% RCS + 30% STT showed lower levels of moisture content of 35.88% and these were

statistically at par with the fruits treated with thinning intensity @ 30% RCS alone where

moisture content of 35.91% was recorded in Hillawi cultivar. Higher level of moisture

contents of 40.85% was recorded in fruits where no thinning was practiced in Khadrawi

cultivar (Table 4.11). Whereas, the Hillawi fruits attained minimum level of moisture

content of 37.17% as compared to the fruits of Khadrawi where moisture content of

38.24% was observed. Meanwhile, the strands thinning intensity @ 20% RCS alone and

in combination of 20% RCS + 20% STT tended to have an intermediate effect on fruit

moisture content of both date palm cultivars.

4.2.3.1.2 Total soluble solids concentration (oBrix)

Strands thinning treatments and cultivars showed statistically significant results while

their interaction was found non-significant regarding the total soluble solids concentration

99

at rutab stage (Table 4.12). Thinning treatments significantly increased the TSS contents

in fruits as compared to untreated fruits (no thinning) in both date palm cultivars during

both years. Thinning intensity @ 30% RCS + 30% STT achieved higher amounts of TSS

concentration (10.95 oBrix) in fruits and these were at par with the fruits treated with

thinning intensity @ 30% RCS alone where TSS concentration 10.83 oBrix was recorded

in both date palm cultivars. However, lower amounts (7.81 oBrix) of TSS contents were

noted in control fruits subjected to no thinning in both date palm cultivars (Table 4.12).

Regarding the response of both cultivars, Hillawi fruits attained higher (10.39 oBrix) TSS

contents than Khadrawi fruits where TSS concentration of 9.24 oBrix was recorded.

Similarly, strands thinning intensity @ 20% RCS alone and in combination with 20%

RCS + 20% STT showed intermediary effect on TSS concentration of both date palm

cultivars.

4.2.3.1.3 Total titratable acidity (%)

Statistical analysis showed significant differences for strand thinning treatments and

cultivars whereas non-significant difference was found between their interactions

regarding fruit titratable acidity at rutab stage (Table 4.13). Thinning treatments

significantly decreased the acidity level in fruits as compared to fruits where no thinning

was practiced. Higher intensity of strands thinning effectively reduced the level of acidity

in fruit than lower thinning intensity. Fruit thinned @ 30% RCS + 30% STT showed

lower level of acidity (0.131%) and these were statistically at par with the fruits treated

with thinning intensity @ 30% RCS alone where level of acidity in fruits was 0.139%

while the acidity of these fruits were significantly lower as compared to fruits of other

thinning treatments in both cultivars. Maximum level (0.290%) of acidity was noted in

fruits subjected to no thinning treatments in both cultivars (Table 4.13). The fruits of

Khadrawi cultivar attained higher titratable acidity level (0.206%) than the fruits of

Hillawi where titratable acidity value of 0.165% was measured. The intermediate effect

was noted in fruits subjected to thinning intensity @ 20% RCS alone on total titratable

acidity of both date palm cultivars.


)

Ascorbic acid at rutab stage was significantly affected by strand thinning, cultivars and

their interaction in both date palm cultivars (Table 4.14). Strands thinning treatments

significantly increased the amount of ascorbic acid in fruit as compared to control fruit

(no thinning). Thinning intensity @ 30% RCS + 30% STT produced greater (1.61 mg 100

g-1

) amount of ascorbic acid contents in Hillawi fruits and these were statistically similar

100

to the fruit of Hillawi having thinning intensity @ 20% RCS + 20% STT and 30% RCS

alone where ascorbic acid values of 1.58 and 1.56 mg 100 g-1

, respectively. Whereas,

lower levels (1.02 and 1.09 mg 100 g-1

) of ascorbic acid were noted in untreated fruits (no

thinning) of Khadrawi and Hillawi cultivars, respectively (Table 4.14). The Hillawi fruit

attained higher ascorbic acid of 1.44 mg 100 g-1

as compared to Khadrawi fruits where

ascorbic acid of 1.36 mg 100 g-1

was recorded. The fruits subjected to strands thinning

intensity @ 20% RCS alone and in combination of 20% RCS + 20% STT showed

intermediate effect on ascorbic acid of both date palm cultivars.

Table 4.11 Effects of different strands thinning intensities on fruit moisture

content (%) of Hillawi and Khadrawi date palm fruit.

Thinning treatments Fruit moisture contents (%)


No thinning 38.89 b 40.85 a 39.87 A

20% RCS 36.39 f 37.42 d 36.91 C

30% RCS 35.91 g 37.17 e 36.54 D

20% STT 38.41 c 38.85 b 38.63 B

30% STT 38.38 c 38.83 b 38.60 B

20% RCS+20%STT 36.37 f 37.40 d 36.88 C

30%RCS+30%STT 35.88 g 37.15 e 36.51 D

Mean 37.17 B 38.24 A





101

Table 4.12 Effects of different strands thinning intensities on total soluble solids

concentration (oBrix) of Hillawi and Khadrawi date palm fruit.

Thinning treatments Total soluble solids (

oBrix)


No thinning 8.20 7.42 7.81 F

20% RCS 10.79 9.54 10.16 C

30% RCS 11.42 10.23 10.83 A

20% STT 9.78 8.40 9.09 E

30% STT 9.98 8.98 9.48 D

20% RCS+20%STT 10.96 9.82 10.39 B

30%RCS+30%STT 11.58 10.31 10.95 A

Mean 10.39 A 9.24 B





Table 4.13 Effects of different strands thinning intensities on total titratable

acidity (%) of Hillawi and Khadrawi date palm fruit.

Thinning treatments Total titratable acidity (%)


No thinning 0.271 0.310 0.290 A

20% RCS 0.142 0.187 0.165 C

30% RCS 0.122 0.155 0.139 D

20% STT 0.189 0.239 0.214 B

30% STT 0.178 0.227 0.202 B

20% RCS+20%STT 0.140 0.173 0.156 C

30%RCS+30%STT 0.114 0.148 0.131 D

Mean 0.165 B 0.206 A





102

Table 4.14 Effects of different strands thinning intensities on ascorbic acid (mg

100 g-1

) of Hillawi and Khadrawi date palm fruit.

Thinning treatments Ascorbic acid (mg 100 g

-1)


No thinning 1.09 h 1.02 h 1.05 F

20% RCS 1.46 cd 1.39 efg 1.42 D

30% RCS 1.56 ab 1.41 def 1.48 BC

20% STT 1.34 fg 1.32 g 1.33 E

30% STT 1.44 de 1.46 cde 1.45 CD

20% RCS+20%STT 1.58 ab 1.44 de 1.51 B

30%RCS+30%STT 1.61 a 1.52 bc 1.56 A

Mean 1.44 A 1.36 B





4.2.3.1.5 Glucose (%)

Analyzed data presented in Table 4.15 showed statistically significant results for strand

thinning treatments, cultivars and their interaction on glucose in fruit at rutab stage.

Strands thinning significantly increased the level of glucose in fruit as compared to fruits

where no thinning was practiced in both date palm cultivars. Fruits subjected to higher

degree of strand thinning showed maximum level of glucose than fruits treated with lower

thinning intensities. The interaction between thinning treatments and cultivars shows that

strands thinning intensity @ 30% RCS + 30% STT attained higher level of glucose

(30.36%) in Hillawi fruits and these were statistically at par with the fruits treated with

thinning intensity @ 30% RCS alone in Hillawi cultivar. Minimum value of glucose

(16.88%) was recorded in fruits subjected to no thinning treatments in Khadrawi cultivar

(Table 4.15). Regarding the response of both cultivars, the fruits of Hillawi attained more

glucose (26.38%) as compared to the fruits of Khadrawi where glucose of 23.67% were

recorded. The fruits subjected to strands thinning @ 20% RCS and in combination of

20% RCS + 20% STT showed intermediate effect on glucose of both date palm cultivars.

4.2.3.1.6 Fructose (%)

Statistical analysis of fructose at rutab stage showed significant differences for strands

thinning treatments, cultivars and their interaction (Table 4.16). Fruit treated with

different strand thinning intensities showed greater amounts of fructose than untreated

103

fruits (no thinning). Thinning intensity @ 30% RCS + 30% STT showed higher level of

fructose (29.40%) in the fruits of Hillawi and these were statistically at par with those

fruits treated with thinning intensity @ 30% RCS alone where fructose of 28.56% were

noted in Hillawi cultivar. Whereas, minimum level of fructose (16.10%) were noted in

control fruits of Khadrawi cultivar and these were at par with the Hillawi fruits with no

thinning (control) where fructose level of 16.86% was measured (Table 4.16). The

Hillawi fruits attained higher amounts of fructose (25.16%) than the fruits of Khadrawi

where fructose of 22.53% was recorded. In the meanwhile, the strands thinning intensity

@ 20% RCS and in combination of 20% RCS + 20% STT tended to have an intermediary

effect on fructose of both date palm cultivars.

4.2.3.1.7 Sucrose (%)

The effects of strands thinning treatments, cultivars and their interaction were found

statistically significant regarding the sucrose in fruit at rutab stage (Table 4.17). Strands

thinning treatments significantly increased the level of sucrose in fruit as compared to

fruits where no thinning was practiced in both date palm cultivars. Strands thinning

intensity @ 30% RCS + 30% STT achieved higher amounts of sucrose (6.96%) in Hillawi

fruit and these were at par with fruits treated with thinning intensity @ 30% RCS alone

where sucrose contents of 6.77% were noted in Hillawi cultivar. The minimum amounts

of sucrose (3.22%) were noted in fruits subjected to no thinning treatments in Khadrawi

date palm (Table 4.17). The fruit of Hillawi attained maximum sucrose of 5.83% as

compared to Khadrawi fruits where sucrose of 5.06% was recorded. The intermediate

effect was observed in fruits those were treated with thinning intensity @ 20% RCS alone

and in combination with 20% RCS + 20% STT regarding the sucrose of both date palm

cultivars.

4.2.3.1.8 Reducing sugars (%)

Statistical analysis in Table 4.18 showed significant differences for strand thinning

treatments, cultivars and their interaction regarding the reducing sugars in fruit at rutab

stage. Strands thinning significantly increased the reducing sugar contents in fruits as

compared to the fruit of no thinning. Strands thinning intensity @ 30% RCS + 30% STT

showed higher level of reducing sugars (59.76%) in Hillawi fruits and these were at par

with thinning intensity @ 305 RCS alone in Hillawi date palm. Whereas, lower amounts

of reducing sugars (32.99%) were recorded in control fruit of Khadrawi cultivar and these

were statistically similar to the fruits of Hillawi having no thinning where reducing sugars

of 35.12% were noted (Table 4.18). However, fruit of Hillawi attained higher level of

104

reducing sugar contents (51.55%) than the fruit of Khadrawi where reducing sugars level

of 46.21% was recorded. The strands thinning @ 20% RCS alone and in combination of

20% RCS + 20% STT showed intermediate effect on reducing sugars of both date palm

cultivars.

4.2.3.1.9 Total sugars (%)

Total sugars in fruit at rutab stage were significantly affected by strand thinning

treatments, cultivars and their interaction (Table 4.19). Strands thinning treatments

effectively increased accumulation of total sugars in fruit as compared to fruits of control

(no thinning). Thinning at higher intensity showed maximum production of total sugar

contents than the fruits subjected to lower thinning intensities. Strands thinning @ 30

RCS + 30% STT achieved higher level of total sugars (66.73%) in Hillawi fruits and

these were statistically at par with the fruit having thinning intensity @ 30% RCS alone in

Hillawi fruit. The fruit subjected to no thinning treatments showed minimum level

(36.21%) of total sugars in Khadrawi date palm (Table 4.19). Hillawi fruit attained more

total sugars of 57.38% than Khadrawi fruits where total sugars of 51.27% were recorded.

The fruits subjected to strands thinning intensity @ 20% RCS alone and in combination

with 20% RCS + 20% STT tended to have an intermediary effect on total sugars of both


Table 4.15 Effects of different strands thinning intensities on glucose (%) of


Thinning treatments Glucose contents (%)


No thinning 18.25 g 16.88 h 17.56 E

20% RCS 27.66 c 25.40 de 26.53 C

30% RCS 29.72 ab 25.73 de 27.72 AB

20% STT 24.74 e 22.31 f 23.52 D

30% STT 24.93 e 23.35 f 24.14 D

20% RCS+20%STT 29.03 b 25.37 de 27.20 BC

30%RCS+30%STT 30.36 a 26.67 cd 28.52 A

Mean 26.38 A 23.67 B





105

Table 4.16 Effects of different strands thinning intensities on fructose (%) of


Thinning treatments Fructose contents (%)


No thinning 16.86 j 16.10 j 16.48 E

20% RCS 26.60 cd 23.82 fg 25.21 C

30% RCS 28.56 ab 24.60 ef 26.58 AB

20% STT 23.06 gh 21.42 i 22.24 D

30% STT 23.75 fg 22.21 hi 22.98 D

20% RCS+20%STT 27.90 bc 24.04 fg 25.97 BC

30%RCS+30%STT 29.40 a 25.54 de 27.47 A

Mean 25.16 A 22.53 B





Table 4.17 Effects of different strands thinning intensities on sucrose (%) of


Thinning treatments Sucrose contents (%)


No thinning 3.91 j 3.22 k 3.56 E

20% RCS 6.21 bc 5.16 gh 5.68 C

30% RCS 6.77 a 5.82 de 6.29 A

20% STT 5.15 gh 4.77 i 4.96 D

30% STT 5.42 fg 4.89 hi 5.16 D

20% RCS+20%STT 6.38 b 5.54 ef 5.96 B

30%RCS+30%STT 6.96 a 5.99 cd 6.48 A

Mean 5.83 A 5.06 B





106

Table 4.18 Effects of different strands thinning intensities on reducing sugars (%)


Thinning treatments Reducing sugar contents (%)


No thinning 35.12 h 32.99 h 34.05 E

20% RCS 54.27 c 49.22 e 51.74 C

30% RCS 58.28 ab 50.34 de 54.31 AB

20% STT 47.81 ef 43.73 g 45.77 D

30% STT 48.68 e 45.57 fg 47.12 D

20% RCS+20%STT 56.93 b 49.42 e 53.17 BC

30%RCS+30%STT 59.76 a 52.22 cd 55.99 A

Mean 51.55 A 46.21 B





Table 4.19 Effects of different strands thinning intensities on total sugars (%) of


Thinning treatments Total sugar contents (%)


No thinning 39.03 i 36.21 j 37.62 E

20% RCS 60.48 c 54.38 ef 57.43 C

30% RCS 65.06 ab 56.16 de 60.61 AB

20% STT 52.96 fg 48.50 h 50.73 D

30% STT 54.11 ef 50.46 gh 52.29 D

20% RCS+20%STT 63.31 b 54.97 ef 59.14 BC

30%RCS+30%STT 66.73 a 58.22 cd 62.47 A

Mean 57.38 A 51.27 B





107

4.2.4.1 Fruit phytonutritional traits

4.2.4.1.1 Total phenolics (mg GAE/100 g)

Total phenolics in fruit at rutab stage were significantly affected by strands thinning

treatments and cultivars while their interaction was non-significant (Table 4.20). Strands

thinning significantly increased the level of total phenolics in treated fruits as compared

to fruits of control (without thinning) in both date palm cultivars. Strands thinning

intensity @ 30% RCS + 30% STT showed higher level of total phenolics (179.86 mg

GAE/100 g) in fruits and these were statistically at par with the fruits having thinning

intensity @ 30% RCS alone where TPC of 176.73 mg GAE/100 g was recorded.

Whereas, lower amounts of TPC (114.64 mg GAE/100 g) were noted in untreated fruits

(no thinning) (Table 4.20). The fruit of Khadrawi showed more TPC contents (162.87 mg

GAE/100 g) as compared to the Khadrawi fruits where TPC of 154.17 mg GAE/100 g

was measured. The fruits subjected to strands thinning intensity @ 20% RCS alone and in

combination of 20% RCS + 20% STT tended to have intermediate effect on TPC of both


4.2.4.1.2 Total flavonoids (mg CEQ/100 g)

The analyzed data regarding total flavonoids at rutab stage showed statistically significant

differences but non-significant for their interaction (Table 4.21). Strands thinning

significantly increased the TFC in fruit as compared to untreated fruits (no thinning) in

both cultivars. Strands thinning intensity @ 30% RCS + 30% STT showed maximum

amounts of TFC (57.81 mg CEQ/100 g) in fruits these were at par to the fruits with

thinning intensity @ 30% RCS alone where TFC of 56.50 mg CEQ/100 g were recorded.

Whereas, lower level of TFC (21.82 mg GAE/100 g) were noted in fruits where no

thinning was practiced (Table 4.21). Regarding the response of both cultivars, Hillawi

fruits attained higher amounts of TFC (49.60 mg CEQ/100 g) as compared to the fruits of

Khadrawi where TFC of 44.26 mg CEQ/100 g was measured. Meanwhile, the strands

thinning intensity @ 20% RCS alone and in combination of 20% RCS + 20% STT

showed intermediary effect on TFC of both date palm cultivars.

4.2.4.1.3 Total tannins (%)

The effects of strands thinning treatments and cultivars were found statistically significant

while their interaction showed non-significant differences regarding the total tannins in

fruits at rutab stage (Table 4.22). Total tannins decreased rapidly with the progression of

fruit ripening. Strands thinning treatments effectively reduced the level of total tannin

108

contents in fruit as compared to the fruits subjected to no thinning in both date palm

cultivars. Strands thinning intensity @ 30% RCS + 30% STT showed lower amounts of

total tannins (0.237%) in fruit and these were at par with the fruits having thinning

intensity @ 30% RCS alone where total tannins of 0.250% were noted. Maximum values

of total tannins (0.655%) were noted in fruit subjected to no thinning treatments (Table

4.22). The fruit of Hillawi attained lower (0.362%) total tannin contents as compared to

the fruits of Khadrawi cultivar where total tannins of 0.393% were recorded. The strands

thinning intensity @ 20% RCS alone and in combination of 20% RCS + 20% STT

showed intermediate effect regarding the total tannins in both date palm cultivars.

4.2.4.1.4 Total antioxidants (%)

Total antioxidants in fruits at rutab stage were significantly affected by strands thinning

treatments and cultivars while interaction between them was found non-significant (Table

4.23). Strands thinning efficiently increased the total antioxidants activities in fruits as

compared to fruits where no thinning was performed. Strands thinning intensity @ 30%

RCS + 30% STT showed higher antioxidants (70.76%) in fruits and these were at par

with the fruits having thinning intensity @ 30% RCS alone where total antioxidants

activities of 70.10% were measured. Whereas, lower antioxidants activities (38.33%)

were recorded in untreated fruits (no thinning) (Table 4.23). The Khadrawi fruits attained

higher antioxidants activities (61.64%) as compared to Khadrawi fruits where

antioxidants activities of 57.99% were recorded. In the meanwhile, the fruits subjected to

strands thinning intensity @ 20% RCS alone and in combination of 20% RCS + 20%

STT tended to have intermediate effect on total antioxidants activities of both date palm

cultivars.

109

Table 4.20 Effects of different strands thinning intensities on total phenolics (mg

GAE/100 g) of Hillawi and Khadrawi date palm fruit.

Thinning treatments Total phenolics (mg GAE/100 g)


No thinning 111.20 118.07 114.64 E

20% RCS 159.84 166.68 163.26 B

30% RCS 171.70 181.76 176.73 A

20% STT 149.21 155.03 152.12 D

30% STT 153.36 162.07 157.71 C

20% RCS+20%STT 161.27 169.41 165.34 B

30%RCS+30%STT 172.64 187.07 179.86 A

Mean 154.17 B 162.87 A





Table 4.21 Effects of different strands thinning intensities on total flavonoids (mg

CEQ/100 g) of Hillawi and Khadrawi date palm fruit.

Thinning treatments Total flavonoids (mg CEQ/100 g)


No thinning 24.77 18.88 21.82 D

20% RCS 52.03 47.99 50.01 B

30% RCS 60.27 52.73 56.50 A

20% STT 46.28 42.42 44.35 C

30% STT 50.40 45.87 48.14 B

20% RCS+20%STT 51.81 47.93 49.87 B

30%RCS+30%STT 61.64 53.99 57.81 A

Mean 49.60 A 44.26 B





110

Table 4.22 Effects of different strands thinning intensities on total tannins (%) of


Thinning treatments Total tannin contents (%)


No thinning 0.623 0.686 0.655 A

20% RCS 0.288 0.308 0.298 D

30% RCS 0.231 0.270 0.250 E

20% STT 0.461 0.493 0.477 B

30% STT 0.435 0.446 0.440 C

20% RCS+20%STT 0.280 0.295 0.287 D

30%RCS+30%STT 0.218 0.256 0.237 E

Mean 0.362 B 0.393 A





Table 4.23 Effects of different strands thinning intensities on total antioxidants


Thinning treatments Total antioxidants activities (%)


No thinning 36.95 39.72 38.33 F

20% RCS 59.99 64.08 62.04 C

30% RCS 68.43 71.77 70.10 A

20% STT 53.53 57.26 55.39 E

30% STT 56.43 58.78 57.60 D

20% RCS+20%STT 61.91 67.10 64.50 B

30%RCS+30%STT 68.66 72.74 70.70 A

Mean 57.99 B 61.64 A





111

4.2.2 Discussion

Fruit quality is a chief component to attain maximum economic return and develop

healthy relationship between supply and demand. In spite of profuse date’s production in

the country, growers do not pay any concentration for improving the fruit physical and

quality characters and fetch low market prices. Uneven fruit maturity/ripening in date

palm are a common problem which results poor quality fruits with less economic return.

Fruit thinning is an important managerial approach to achieve constant yields of high

quality fruits with respect to fruit size and nutrient contents (Lippert and Blanke, 2004).

Therefore, present study was carried out to investigate the effects of strand thinning to

accelerate the fruit maturity and quality composition in date fruit. Fruit maturation period

from early kimri to late kimri, late khalal and rutab stages indicated that strand thinning

treatments play an important role to accelerate the fruit maturation period in Hillawi and

Khadrawi date palm cultivars. This acceleration in fruit maturation period might be due to

the accumulation and proper supply of assimilates and photosynthates to remaining

individual fruits by thinning treatments. Fruit thinning is effective after four to six weeks

of full bloom because of less competition for food among young fruits and to ensure a

proper supply of assimilates and photosynthates right from the moment of fruit formation

(Di Marco et al., 1992). Cluster thinning has an important role in plants to induct

physiological adjustments by improving the kinetics of fruits maturation. It is because

thinning improves the sanitary conditions under the canopy and allows more

enlightenment and fresh air penetration in the remaining fruit clusters (Smithyman et al.,

1998).

In the current study, strands thinning significantly reduced the fruits maturation period as

compared to fruits where no thinning was applied in both date palm cultivars. Fruits

treated with strands thinning took shorter time to complete the period from early kimri to

late kimri, early kimri to late khalal and early kimri to rutab stages as compared to un-

thinned fruits in both Hillawi and Khadrawi date palm cultivars. Strands thinning

intensity @ 30% RCS alone and 30% RCS + 30% STT accelerated the fruit ripening

processes and shortened the period by about 10 days from early kimri to rutab stage.

These results are correlated with Myers et al., (1993) who reported that fruit thinning

significantly accelerated the fruit maturity period in peaches. Khademi (1998) reported

that thinning of central strands at pollination time is much more effective in accelerating

the ripening time of ‘Kabkaab’ dates. Strands thinning also increased the rutab fruit yield

112

per bunch and produced more uniformly ripe fruits than the fruits subjected to no

thinning. Strands thinning intensity @ 30% RCS + 30% STT and 30% RCS alone showed

higher rutab fruit yield per bunch and greater uniform fruit ripening index in both the date

palm cultivars. This might be due to the involvement of more light penetration and air

circulation within the fruit bunches that leads to fast and uniformly ripe fruits. It might

also be possible that thinned fruits received sufficient nutrients and water from the main

stem or bunches due to less competition among the remaining fruit and develop their

physiological and chemical constituents of maturation as quickly and uniformly as

compared to un-thinned fruits. However, in date palm no documented evidence is

available which explain this phenomenon but these results are correlates with Bonora et

al. (2013) they supports this explanation and concluded that balanced fruits density in

nectarine trees produced fruits with high homogeneity in terms of growth, maturation and

soluble solids contents.

Strands thinning treatments significantly affected the fruits physical characters in both

date palm cultivars as compared to no thinning fruits in both date palm cultivars. Strands

thinning intensity @ 30% RCS + 30% STT and 30% RCS alone showed higher fruit

weight, fruit length, fruit width and flesh weight in both date palm cultivars. The reasons

are same as explained above but some others can also strengthen these reasons. The

improvement in fruits growth physical parameters could be due to the abundance

accumulation of photosynthates to the remaining fruit strands (Ali-Dinar et al., 2002;

Soliman et al., 2011; Soliman and Harhash, 2012). It is because that initial fruits

development/pericarp growth is regulated by cell division and cell enlargement and also

these processes dependent on photosynthesis (Hole and Scott, 1981). Sun light exposure

is also important to regulate the metabolism of carbon and assimilates in young growing

fruits. In contrast, control fruits (un-thinned) had less light exposure due to high density

that reduced the sink strength and fruits could not develop their growth properly and

uniformly. It is reported that regulation of fruits growth and development are dependent

on light which influenced the activity of phytohormones (Coombe, 1973). Our results are

correlated with the findings of Goffinet et al. (1995) they reported that fruit thinning

reduced the crop load and remaining fruits showed increased fruit size. Thinning reduced

the number of fruit per shoot/tree while the remaining fruits increase their dimensions due

to proper light and photosynthesis as found in mango (Mendoza and Wills 1984), pear

(Kappel and Neilsen 1994) and apple (Morgan et al. 1984). These findings are in line

113

with Costa and Vizzotto (2000) who reported that thinning of fruits in peaches reduced

the competition between fruits and vegetative sinks and enhance the fruit size.

Strands thinning treatments efficiently improved the biochemical characters in fruits as

compared to un-thinned fruits in both cultivars. Strands thinning intensity @ 30% RCS

alone and 30% RCS + 30% STT showed higher TSS, ascorbic acid, sugars accumulation

and decreased the level of acidity as compared to no thinning. The reasons are same as

reported in earlier paragraphs but some coworkers also support these reasons. Fruits

subjected to strand thinning treatments showed lower level of moisture contents than

fruits without thinning. These results are correlated with Blanke and Leyhe (1987) who

reported that fruits exposed to more sun-light showed higher transpiration rate as

compared to control fruits (Blanke and Leyhe, 1987). The increase in TSS, ascorbic acid

and decrease in acidity are supported by different coworkers (Mostafa and El-Akkad,

2011; Iizadi et al., 2010; Soliman et al., 2011). More sugars accomulation in thinned

fruits are also supported are in line with Brown and Coombe (1985) and (Crippen and

Morrison, 1986) who reported that light exposure regulates the activity of invertase

enzyme which is responsible for sugars accumulation in grape berries.

Fruit phytonutrients (total phenolics, total flavonoids and total antioxidants) were

significantly improved and tannin contents were decreased by strand thinning treatments

in both date palm cultivars. Strands thinning @ 30% RCS alone and 30% RCS + 30%

STT showed higher levels of phytonutrients in fruits at rutab stage than no thinning

treatments. The greater improvement in quality of total phenolics, total flavonoids, total

antioxidants and reduction of total tannins in thinning treatments confirmed our previous

explanation as reported in physical and chemical parameters. The main reason is that

more exposure of light due to less fruits density; it is because light plays an important role

in processes which are responsible for the accumulation of anthocyanins and phenolic

compounds (Wicks and Kliewer 1983, Dokoozlian and Kliewer 1996). These findings

were supported by Bubola et al. (2011) and Profio et al. (2012) who reported that cluster

thinning significantly increased the accumulation of phenolics in grape berries. On the

other hand, un-thinned fruits could not attain proper return due to less availability of light

or air circulation that affects the rate of photosynthetic carbon assimilation rate (Morrison

and Noble, 1990).

The findings of the present study have an important commercial implication that strands

thinning at early fruit stages (4 weeks after pollination) accelerated the fruits maturation

processes and reduced the period about 10 days and also improved the fruit physical,

114

chemical and phytonutritional composition in both date palm cultivars. Strands thinning

intensity @ 30% RCS alone and 30% RCS + 30% STT effectively reduced the fruit

maturity cycle and improved the fruit quality in Hillawi and Khadrawi cultivars which is

confirmed from this comprehensive study. These findings could be helpful in achieving

the desired goal. Growers can minimize the date fruit losses occurred due to monsoon

rains by harvesting the fruit 10 days earlier by adopting strands thinning technologies.

Moreover, large fruit size, uniformity in ripening and good quality fruits can increase the

return.

4.2.3 Conclusion

In conclusion, strands thinning at early kimri stage reduced the period of 10 days beyond

of control fruit (without thinning) from kimri to rutab stage by accelerating the maturation

processes. Strands thinning intensity (30% RCS alone) resulted in higher yield of 5.22 kg

per bunch and more uniformly ripe fruit (76.28%) at rutab stage in both date palm

cultivars during both years. The total soluble solids concentration, ascorbic acid, sugars

(glucose, fructose, and sucrose), total phenolics, total flavonoids and total antioxidants

were significantly improved while titratable acidity and total tannin contents were

decreased in thinned fruit. Strands thinning intensity @ 30% RCS alone proved best

thinning treatment for obtaining the desired fruit quality traits as compared to other

thinning intensities. Meanwhile, the fruits subjected to strands thinning intensity (20%

RCS alone) tended to have an intermediate effect on all the measured parameters of both


115

4.3. Study-3 Ripening and quality assessment of date palm fruit by

the influence of hot water treatment.

4.3.1 Results

4.3.1.1 Fruit physical traits

4.3.1.1.1 Time taken to reach the fruit at tamar stage (days)

The presented data in Figure 4.45 showed statistically significant differences (p ≤ 0.05)

regarding the effects of hot water treatments and cultivars while interaction between them

was found non-significant for time taken to reach at tamar stage by the fruit. The fruits

those were immersed in hot water for longer duration reached earlier at tamar stage as

compared to the fruits of shorter duration. Hot water treatments exposure for 7 min at

65oC took shorter time of 6.16 and 7.83 days to reach at tamar stage by the fruits. While,

more time of 11.66 and 11.33 days to reach the fruits at tamar stage were noted in

untreated fruits and HWT for 1 min at 65oC, respectively and these were at par with each

other. The fruits of Hillawi took shorter time of 8.86 days to reach at tamar stage as

compared to the fruits of Khadrawi those took 9.66 days to accomplish that period. The

fruits subjected to 5 min hot water immersion showed intermediate effect regarding time

taken to reach the fruit at tamar stage in both date palm cultivars.

4.3.1.1.2 Uniform fruit ripening index (%)

Statistically significant differences were found at p ≤ 0.05 regarding the effects of hot

water treatments and interaction while cultivars showed non-significant results for

uniform fruit ripening index (Figure 4.46). Fruit immersed in higher temperature of 7 min

at 65oC did not show uniformity in fruit ripening as compared to lower temperatures. The

higher uniform fruit ripening index of 69.00% was noted in fruits those were treated with

hot water with an exposure time of 5 min at 65oC and minimum uniform fruit ripening

index of 11.25% was recorded in untreated fruits. The interaction between hot water

treatments and cultivars showed that maximum uniform fruit ripening indexes of 81.66

and 73.33% were noted in fruits those were treated with hot water with an exposure time

of 5 and 3 min at 65oC in Hillawi and Khadrawi cultivars, respectively and these were at

par with each other. Whereas, minimum uniform fruit ripening indexes of 10.70 and

11.81% were recorded in untreated fruits of Hillawi and Khadrawi and these were at par

with the fruits those were treated with hot water with an exposure time of 7 min and 1

min at 65oC in Hillawi and Khadrawi fruits where uniform fruit ripening indexes were

116

16.30 and 20.88%, respectively and these were at par with each other. The hot water

immersion for 3 min at 65oC tended to have an intermediate effect on uniform fruit

ripening of both date palm cultivars.

4.3.1.1.3 Fruit weight loss (%)

Effects of hot water treatments and cultivars were found statistically significant (p ≤ 0.05)

while their interaction showed non-significant difference regarding the fruit weight loss at

tamar stage (Figure 4.47). Fruit weight loss increased positively at higher temperature as

compared to lower ones. Hot water treatment with an exposure time of 7 min at 65oC

showed higher loss in weight of 22.87% and minimum loss in weight of 11.73% was

noted in untreated fruits and these were at par with the fruits those were treated with hot

water with an exposure times of 1 min and 3 min at 65oC where losses in weights were

12.96 and 14.51% in fruits, respectively. The fruits of Khadrawi showed minimum loss in

weight (14.26%) than the fruits of Hillawi where loss in weight of 17.35% was recorded.

The fruits subjected to hot water immersion for 1 and 3 min at 65oC showed intermediate

effect regarding the fruit weight loss of both date palm cultivars.

4.3.1.1.4 Fruit moisture content (%)

Moisture content in fruit at tamar stage showed statistically significant differences (p ≤

0.05) regarding the effects of hot water treatments, cultivars and interaction between them

(Figure 4.48). Higher temperature effectively decreased the moisture contents in fruits as

compared to lower temperature. Fruits those were immersed in hot water with an

exposure time of 7 min at 65oC showed lower amounts of moisture content (16.97%) in

fruits and higher level of moisture contents of 29.73% was noted in fruits those were

untreated. The fruits of Khadrawi showed higher level of moisture contents (26.63%) as

compared to the fruits of Hillawi where moisture content was 21.77%. The interaction

between hot water treatments and cultivars showed that fruits those were immersed in hot

water with an exposure time of 7 min at 65oC showed lower level of moisture content

(11.32%). Whereas, fruits those were untreated and dipped in hot water for 1 min at 65oC

showed higher levels of moisture contents (30.66, 28.81 and 28.36%) in Khadrawi,

Hillawi and Khadrawi, respectively and these were at par with each other. The

intermediate effect on moisture content was recorded in fruits those were immersed in hot

water for 3 min at 65oC in both date palm cultivars.

4.3.1.1.5 Fruit flesh weight (g)


water treatments and cultivars while interaction between them showed non-significant

117

results for fruit flesh weight at tamar stage (Figure 4.49). Higher temperature significantly

decreased the fruit flesh weight as compared to fruits those were immersed in low

temperature. Lower values of flesh weights (4.34 and 4.66 g) were recorded in fruits

those were immersed in hot water with an exposure times of 7 min and 5 min at 65oC,

respectively and these were at par with each other. While, higher flesh weight of 5.55 g

was noted in untreated fruits and these were at par with the fruits those were dipped in hot

water for 1 min and 3 min where flesh weights were 5.44 and 5.14 g in fruits, respectively

and these were at par with each other. Khadrawi fruits showed maximum flesh weight

(5.39 g) as compared to the fruits of Hillawi where flesh weight of 4.66 g was noted.

4.3.1.1.6 Fruit pit weight (g)

The analysed data presented in Figure 4.50 showed significant differences (p ≤ 0.05)

regarding the effects of hot water treatments while cultivars and interaction between them

was found non-significant for fruit pit weight. Fruits those were immersed in higher

temperature of 7 min at 65oC effectively decreased the pit weight as compared to fruits

those were immersed in low temperature. Higher pit weight of 0.73 g was noted in fruits

those were untreated and these were at par with the fruits those were immersed in hot

water for 1 min and 3 min at 65oC where pit weights were 0.70 and 0.65 g, respectively

and these were at par with each other. Whereas, lower pit weights (0.54 and 0.61 g) were

recorded in fruits those were treated with hot water with an exposure times of 7 min and 5

min at 65oC, respectively and these were at par with each other.

118

Figure 4.45 Effects of hot water treatments at 65oC on time taken to tamar stage

(days) of Hillawi and Khadrawi date palm fruit ±S.E.

Figure 4.46 Effects of hot water treatments at 65oC on uniform fruit ripening

index (%) of Hillawi and Khadrawi date palm fruit ± S.E.

0

2

4

6

8

10

12

14T

ime t

o t

am

er s

tag

e (

da

ys)

Duration of HWT at 65oC

Hillawi Khadrawi

0

10

20

30

40

50

60

70

80

90

Un

ifo

rm

rip

en

ing

in

dex (

%)


Hillawi Khadrawi

119

Figure 4.47 Effects of hot water treatments at 65oC on fruit weight loss (%) of


Figure 4.48 Effects of hot water treatments at 65oC on moisture content (%) of


0

5

10

15

20

25

30W

eig

ht

loss

(%

)

Hillawi Khadrawi

0

5

10

15

20

25

30

35

Mo

istu

re c

on

ten

t (%

)


Hillawi Khadrawi

120

Figure 4.49 Effects of hot water treatments at 65oC on fruit flesh weight (%) of


Figure 4.50 Effects of hot water treatments at 65oC on pit weight (%) of Hillawi


0

1

2

3

4

5

6

7F

ru

it f

lesh

weig

ht

(g)


Hillawi Khadrawi

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Fru

it p

it w

eig

ht

(g)


Hillawi Khadrawi

121

Control (cv. Hillawi) HWT for 1 min (cv. Hillawi)

HWT for 3 min (cv. Hillawi) HWT for 5 min (cv. Hillawi)

HWT for 7 min (cv. Hillawi)

Slide-4.1: Effects of hot water treatment (HWT) on the ripening behaviour of

Hillawi fruit under ambient conditions.

122

Control (cv. Khadrawi) HWT for 1 min (cv. Khadrawi)

HWT for 3 min (cv. Khadrawi) HWT for 5 min (cv. Khadrawi)

HWT for 7 min (cv. Khadrawi)

Slide-4.2: Effects of hot water treatment (HWT) on the ripening behaviour of

Khadrawi fruit under ambient conditions.

123

4.3.1.2 Fruit biochemical traits

4.3.1.2.1 Total soluble solids concentration (oBrix)

Statistically significant differences (p ≤ 0.05) were found regarding the effects of hot

water treatments, cultivars and their interaction on total soluble solids concentration in

fruit at tamar stage (Figure 4.51). High degree of temperature for 7 min at 65oC

progressively lowers down the TSS concentration than low degree of temperature. Higher

amounts of total soluble solids concentration of 9.75 oBrix were noted in fruits those were

immersed in hot water for 3 min at 65oC while fruits those were untreated showed lower

amounts of total soluble solids (4.13 oBrix). The fruits of Hillawi attained higher level of

total soluble solids concentration (7.56 oBrix) as compared to the fruits of Khadrawi

where total soluble solids contents of 7.03 oBrix were recorded. The interaction hot water

treatments and cultivars showed that higher level of total soluble solids contents (11.77

oBrix) were recorded in the Hillawi fruits those were immersed in hot water for 3 min at

65oC. Whereas, lower amounts of total soluble solids concentration of 3.91, 4.36 and 4.69

oBrix were recorded in the fruits of Khadrawi, Hillawi and Khadrawi those were untreated

and immersed in hot water for 1 min at 65oC, respectively and these were at par with each

other. The fruit subjected to hot water immersion for 1 and 5 min at 65oC showed

intermediate effect on TSS concentration of both date palm cultivars.

4.3.1.2.2 Total titratable acidity (%)

The analysed data presented in Figure 4.52 showed statistically significant results (p ≤

0.05) regarding the effects of hot water treatments, cultivars and their interaction on total

titratable acidity in fruits at tamar stage. Lower levels of total titratable acidity of 0.144

and 0.147% were recorded in fruits those were treated with hot water for 5 min at 65oC

while higher level of total titratable acidity of 0.183% was noted in fruits those were

untreated. The Hillawi fruits showed lower level of total titratable acidity (0.144%) than

the fruits of Khadrawi where total titratable acidity of 0.174% was noted. The interaction

between hot water treatments and cultivars showed that the fruits of Hillawi those were

immersed in hot water for 3 min, 1 min and 5 min showed lower values of total titratable

acidity (0.123, 0.138 and 0.142%), respectively and these were at par with each other.

Whereas, higher amounts of total titratable of 0.205 and 0.195% were noted in the fruits

of Khadrawi cultivar those were untreated and immersed in hot water for 1 min at 65oC,

respectively and these were at par with each other.

124


)

Ascorbic acid contents in fruit at tamar stage showed significant differences at p ≤ 0.05

regarding the effects of hot water treatments, cultivars and interaction between them

(Figure 4.53). Maximum amounts of ascorbic acid (0.882 and 0.826 mg 100 g-1

) were

noted in fruits those were untreated and immersed in hot water for 1 min at 65oC,

respectively and these were at par with each other. While, minimum ascorbic acid of

0.741, 0.749 and 0.779 mg 100 g-1

were recorded in fruits those were treated with hot

water for 3 min, 5 min and 7 min at 65oC, respectively and these were at par with each

other. The fruit of Hillawi showed lower amounts of ascorbic acid (0.757 mg 100 g-1

) as

compared to the fruits of Khadrawi where ascorbic acid of 0.834 mg 100 g-1

was

recorded. The interaction between hot water treatments and cultivars showed that the fruit

of Khadrawi cultivar those were untreated and immersed in hot water for 1 min at 65oC

showed higher levels of ascorbic acid (0.944 and 0.909 mg 100 g-1

), respectively and

these were at par with each other. While, lower values of ascorbic acid (0.665, 0.733 and

0.744 mg 100 g-1

) were noted in the fruit of Hillawi, Khadrawi and Hillawi those were

treated with hot water for 3 min, 5 min and 1 min at 65oC, respectively and these were at

par with each other.

Figure 4.51 Effects of hot water treatments at 65oC on total soluble solids

concentration (oBrix) of Hillawi and Khadrawi date palm fruit ± S.E.

0

2

4

6

8

10

12

14

TS

S (

oB

rix)


Hillawi Khadrawi

125

Figure 4.52 Effects of hot water treatments at 65oC on titratable acidity (%) of


Figure 4.53 Effects of hot water treatments at 65oC on ascorbic acid (mg 100 g

-1) of


0

0.05

0.1

0.15

0.2

0.25A

cid

ity

(%

)


Hillawi Khadrawi

0

0.2

0.4

0.6

0.8

1

1.2

Asc

orb

ic a

cid

(m

g 1

00

g-1

)


Hillawi Khadrawi

126

4.3.1.2.4 Glucose (%)

Statistically significant results (p ≤ 0.05) were found regarding the effects of hot water

treatments, cultivars and their interaction on glucose in fruit at tamar stage (Figure 4.54).

High temperature treatment for 7 min at 65oC positively decreased the level of glucose as

compared to low temperature treatments. The fruits those were immersed in hot water for

3 min and 5 min at 65oC showed higher glucose of 30.73 and 29.03%, respectively and

these were at par with each other. While, lower amounts of glucose (16.75%) were

recorded in untreated fruits. The Hillawi fruits showed maximum glucose (27.66%) as

compared to the fruits of Khadrawi where glucose contents of 24.12% were noted. The

interaction between hot water treatments and cultivars showed that fruits those were

treated with hot water for 3 and 1 min at 65oC showed higher glucose of 35.84 and

32.06%, respectively in the fruits of Hillawi cultivar and these were at par with each

other. Whereas, lower amounts of glucose (15.99 and 17.50%) were recorded in the fruits

those were untreated in Khadrawi and Hillawi cultivars, respectively and these were at

par with each other. The fruits subjected to hot water immersion for 1 and 5 min at 65oC

tended to have an intermediate effect on glucose of both date palm cultivars.

4.3.1.2.5 Fructose (%)

Effects of hot water treatments, cultivars and interaction between them showed significant

differences (p ≤ 0.05) regarding the fructose in fruit at tamar stage (Figure 4.55). Fruits

immersed in high temperature for 7 min at 65oC lower down the level of fructose contents

than the fruits immersed in low temperature. The fruits those were treated with hot water

for 3 min and 5 min at 65oC showed higher fructose contents of 28.74 and 27.45%,

respectively and these were at par with each other. While, lower amounts of fructose

contents (14.83%) were noted in the fruits those were untreated. Hillawi fruits showed

maximum fructose contents (26.16%) than the fruits of Khadrawi where fructose of

22.15% were recorded. The interaction between hot water treatments and cultivars

showed that higher level of fructose (33.99%) was noted in the fruits those were

immersed in hot water for 3 min at 65oC in Hillawi cultivar. Whereas, lower amounts of

fructose contents of 14.03 and 15.63% were recorded in the fruits those were untreated in

Khadrawi and Hillawi cultivars, respectively and these were at par with each other. The

intermediary effect was recorded in fruits those were immersed in hot water for 1 and 5

min at 65oC regarding the fructose of both date palm cultivars.

127

4.3.1.2.6 Sucrose (%)

The analysed data presented in Figure 4.56 showed significant differences at p ≤ 0.05

regarding the effects of hot water treatments, cultivars and their interaction on sucrose in

fruit at tamar stage. Fruit sucrose level effectively decreased as well as the duration of hot

water immersion increased. Higher sucrose (2.59 and 2.43%) were noted in fruits those

were treated with hot water for 5 min and 3 min, respectively and these were at par with

each other. While, lower sucrose of 1.22% were recorded in the fruits those were

untreated. The Hillawi fruit showed higher sucrose (2.31%) than the fruits of Khadrawi

where sucrose of 1.84% were noted. The interaction between hot water treatments and

cultivars showed that fruits those were immersed in hot water for 3 min, 1 min and 5 min

at 65oC showed higher sucrose (3.16, 2.73 and 2.70%) in the fruits of Hillawi and

Khadrawi cultivars, respectively and these were at par with each other. Whereas, lower

sucrose of 1.11, 1.24 and 1.33% were recorded in fruits those were untreated, immersed

in hot water for 1 min at 65oC and untreated fruits, respectively and these were at par with

each other.

4.3.1.2.7 Reducing sugars (%)


water treatments, cultivars and their interaction on reducing sugars in fruit at tamar stage

(Figure 4.57). Higher duration heat treatments for 7 min at 65oC positively decreased the

level of reducing sugars than shorter duration heat treatments. The fruits those were

treated with hot water for 3 min and 5 min at 65oC showed higher levels of reducing

sugars (59.47 and 56.48%), respectively and these were at par with each other. While,

lower reducing sugars of 31.58% were noted in the fruits those were untreated. Hillawi

fruits showed higher reducing sugars (53.83%) as compared to the fruits of Khadrawi

where reducing sugars of 46.27% were recorded. The interaction between hot water

treatments and cultivars showed that fruits those were immersed in hot water for 3 min

and 1 min showed higher levels of reducing sugars of 69.83 and 62.79% in the fruit of

Hillawi cultivars, respectively and these were at par with each other. Whereas, fruits those

were untreated showed lower reducing sugars of 30.03 and 33.14% in Khadrawi and

Hillawi cultivar, respectively and these were at par with each other. Hot water immersion

for 1 min at 65oC showed intermediate effect on reducing sugars of both date palm

cultivars.

128

4.3.1.2.8 Total sugars (%)

Total sugars in fruit at tamar stage showed statistically significant differences (p≤0.05)

regarding the effects of hot water treatments, cultivars and interaction between them

(Figure 4.58). Higher duration heat treatments for 7 min at 65oC positively decreased the

level of total sugars than shorter duration heat treatments. Higher amounts of total sugar

contents (61.90 and 59.08%) were recorded in fruits those were treated with hot water for

3 min and 5 min at 65oC, respectively and these were at par with each other. While, lower

total sugars of 32.81% were noted in untreated fruit. The fruit of Hillawi showed

maximum total sugars (56.14%) than the fruit of Khadrawi where total sugars of 48.11%

were recorded. The interaction between hot water treatments and cultivars showed that

fruits those were immersed in hot water for 3 min at 65oC showed higher total sugars of

73.00% in Hillawi cultivar. Whereas, the fruits those were untreated showed lower

amounts of total sugars (31.14 and 34.47%) in Khadrawi and Hillawi cultivar,

respectively and these were at par with each other. The fruits subjected to hot water

immersion for 1 min at 65oC tended to have an intermediate effect on total sugars of both


Figure 4.54 Effects of hot water treatments at 65oC on glucose (%) of Hillawi and


0

5

10

15

20

25

30

35

40

Glu

cose

(%

)


Hillawi Khadrawi

129

Figure 4.55 Effects of hot water treatments at 65oC on fructose (%) of Hillawi and


Figure 4.56 Effects of hot water treatments at 65oC on sucrose (%) of Hillawi and


0

5

10

15

20

25

30

35

40F

ruct

ose

(%

)


Hillawi Khadrawi

0

0.5

1

1.5

2

2.5

3

3.5

Su

cro

se (

%)


Hillawi Khadrawi

130

Figure 4.57 Effects of hot water treatments at 65oC on reducing sugars (%) of


Figure 4.58 Effects of hot water treatments at 65oC on total sugars (%) of Hillawi


0

10

20

30

40

50

60

70

80R

edu

cin

g s

ug

ars

(%

)


Hillawi Khadrawi

0

10

20

30

40

50

60

70

80

To

tal

sug

ars

(%

)


Hillawi Khadrawi

131

4.3.1.3 Fruit phytonutritional traits

4.3.1.3.1 Total phenolics (mg GAE/100 g)


regarding the effects of hot water treatments, cultivars and their interaction on total

phenolics in fruit at tamar stage. Higher total phenolics (182.52 and 182.07 mg GAE/100

g) were recorded in the fruits those were treated with hot water for 3 min and 5 min at

65oC, respectively and these were at par with each other. While, lower amounts of total

phenolic contents of 133.73 mg GAE/100 g were noted in the control fruits. Khadrawi

fruits showed higher total phenolics (172.51 mg GAE/100 g) as compared to the fruits of

Hillawi where total phenolics of 156.17 mg GAE/100 g were noted. The interaction


water for 5 min, 3 min and 7 min at 65oC showed higher total phenolics in Khadrawi,

Hillawi and Khadrawi cultivars, respectively and these were at par with each other.

Whereas, lower total phenolics of 128.03, 139.43, 142.81 and 152.10 mg GAE/100 g

were noted in the fruits those were untreated and immersed in hot water for 7 min and 1

min at 65oC in Hillawi, Khadrawi, Hillawi and Khadrawi cultivars, respectively and these

were at par with each other.

4.3.1.3.2 Total flavonoids (mg CEQ/100 g)

Total flavonoids in fruit at tamar stage showed significant differences (p ≤ 0.05)

regarding the effects of hot water treatments and interaction while cultivars did not differ

significantly (Figure 4.60). The fruits those were immersed in hot water for 3 min, 5 min

and 1 min at 65oC showed higher amounts of total flavonoids (27.80, 26.81 and 24.92 mg

CEQ/100 g), respectively and these were at par with each other. While, lower total

flavonoids of 19.33 mg CEQ/100 g were noted in the control fruits. The interaction

between hot water treatments and cultivars showed that fruits those were treated with hot

water for 3 min, 5 min and 1 min at 65oC showed higher total flavonoids (32.20, 28.52

and 28.17 mg CEQ/100 g) in Hillawi, Khadrawi and Hillawi cultivars, respectively and

these were at par with each other. Whereas, lower total flavonoids (18.48, 20.18, 21.67

and 22.06 mg CEQ/100 g) were recorded in fruits those were untreated and immersed in

hot water for 1 min and 7 min at 65oC in Khadrawi, Hillawi, Khadrawi and Hillawi

cultivars, respectively and these were at par with each other.

4.3.1.3.3 Total tannins (%)


treatments, cultivars and interaction between them on total tannins in the fruit at tamar

132

stage (Figure 4.61). Hot water treatment with an exposure time of 5 min at 65oC showed

lower total tannins of 0.219% and higher total tannins of 0.414% were noted in fruits

those were untreated. The Hillawi fruits showed lower amounts of total tannin contents

(0.267%) than the fruit of Khadrawi where total tannins of 0.325% were recorded. The

interaction between hot water treatments and cultivars showed that fruits those were

treated with hot water for 3 min and 1 min at 65oC showed lower total tannins of 0.161

and 0.192% in Hillawi cultivar, respectively and these were at par with each other. While,

fruits those were untreated showed higher total tannins of 0.435% in Khadrawi cultivar.

4.3.1.3.4 Total antioxidants (%)

The effects of hot water treatments, cultivars and interaction between them were found

significant at p ≤ 0.05 for total antioxidants in the fruit at tamar stage (Figure 4.62).

Higher antioxidants activities of 61.14 and 55.68% were recorded in the fruits those were

treated with hot water with an exposure time of 5 min and 3 min at 65oC, respectively and

these were at par with each other. While, lower total antioxidants of 28.76% were noted

in the control fruit. Khadrawi fruit showed higher total antioxidants activities (50.34%) as

compared to the fruits of Hillawi where total antioxidants activities of 45.33% were

noted. The interaction between hot water treatments and cultivars showed that fruits those

were immersed in hot water for 5 min at 65oC showed higher total antioxidants activities

of 72.84% in Khadrawi cultivar. Whereas, minimum total antioxidants activities of 26.46

and 31.07% were noted in the control fruit of Hillawi and Khadrawi cultivars,

respectively and these were at par with each other.

133

Figure 4.59 Effects of hot water treatments with different timings by keeping

temperature constant at 65oC on total phenolics (mg GAE/100 g) of



temperature constant at 65oC on total flavonoids (mg CEQ/100 g) of


0

50

100

150

200

250T

PC

(m

g G

AE

/10

0 g

)


Hillawi Khadrawi

0

5

10

15

20

25

30

35

40

TF

C (

mg

CE

Q/1

00

g)


Hillawi Khadrawi

134


temperature constant at 65oC on total tannins (%) of Hillawi and



temperature constant at 65oC on total antioxidants (%) of Hillawi


00.05

0.10.15

0.20.25

0.30.35

0.40.45

0.5T

ota

l ta

nn

ins

(%)


Hillawi Khadrawi

0

10

20

30

40

50

60

70

80

Tota

l an

tiox

idan

ts (

%)


Hillawi Khadrawi

135

4.3.1.4 Fruit organoleptic traits

4.3.1.4.1 Colour score


regarding the effects of hot water treatments and interaction while non-significant results

were found in cultivars on colour score. Higher colour score index of 4.33 marked by the

panellist was recorded in fruits those were treated with hot water for an exposure time of

5 min at 65oC. While, minimum colour score indexes of 1.16 and 1.50 ranked by the

panellists in the fruits those were untreated and immersed in hot water for 1 min at 65oC,

respectively and these were at par with each other. The interaction between hot water

treatments and cultivars showed that fruits those were treated with hot water for an

exposure times of 5 min, 2 min and 1 min at 65oC showed higher colour score indexes of

5.00, 4.66 and 4.00 rated by the panellists in Khadrawi, Hillawi and Khadrawi fruits ,

respectively and these were at par with each other. Whereas, minimum colour scores

(1.00, 1.33, 1.33, 1.33 and 1.66) were marked by the panellists in the fruits those were

untreated, immersed in hot water for 7 min, 1 min at 65oC, control and immersed in hot

water for 1 min at 65oC in Khadrawi, Hillawi, Khadrawi and Hillawi fruits, respectively

and these were at par with each other.

4.3.1.4.2 Taste score


water treatments and interaction while cultivars showed non-significant results for taste

scores (Figure 4.64). The fruits those were treated with hot water for an exposure times of

5 min and 3 min at 65oC showed higher taste scores of 4.00 and 3.66 ranked by the

panellists, respectively and these were at par with each other. While, fruits those were

untreated showed lower taste score of 0.50 marked by the panellists. The interaction


water for 5 min, 3 min and 1 min showed higher indexes of taste scores (5.00, 4.66 and

4.00) rated by the panellist, respectively and these were at par with each other. Whereas,

lower indexes of taste scores (0.33, 0.66, 1.33 and 1.33) were marked by the panellists in

the control fruits, immersed in hot water for 7 min and 1 min at 65oC in Hillawi,

Khadrawi, Hillawi and Khadrawi fruits, respectively and these were at par with each

other.

4.3.1.4.3 Texture score

The effects of hot water treatments and interaction were found significant (p ≤ 0.05) while

cultivars showed non-significant results for texture score (Figure 4.65). Maximum texture

136

score indexes of 4.16 and 3.83 were marked by the panellists in the fruits those were

treated with hot water for an exposure times of 5 min and 3 min at 65oC, respectively and

these were at par with each other. While minimum texture score index of 0.83 rated by

the panellist in the control fruits. The interaction between hot water treatments and

cultivars showed that fruits those were untreated, immersed in hot water for 5 min, 3 min

and 1 min at 65oC showed higher colour scores (5.00, 4.66 and 4.00) were marked by the

panellist in Khadrawi, Hillawi and Khadrawi cultivars, respectively and these were at par

with each other. Whereas, minimum texture score indexes of 0.66, 1.00, 1.33 and 1.66

ranked by the panellist in the fruits those were untreated and immersed in hot water for 1

min and 7 min at 65oC in Hillawi, Khadrawi and Hillawi cultivars, respectively and these

were at par with each other.

4.3.1.4.4 Firmness score

The analysed data presented in Figure 4.66 showed significant differences regarding the

effects of hot water treatments and interaction while non-significant difference was found

in cultivars. The fruits those were treated with hot water for an exposure times of 5 min

and 3 min at 65oC showed maximum firmness scores (4.16 and 3.66) marked by the

panellists, respectively and these were at par with each other. The interaction between hot

water treatments and cultivars showed that fruits those were immersed in hot water for 3

min and 5 min at 65oC attained higher firmness scores of 4.66 and 4.66 rated by the

panellist in Hillawi and Khadrawi, respectively and these were at par with each other.

While, minimum firmness score indexes of 0.66, 1.00, 1.33 and 1.33 were marked by the

panellist in the fruits those were untreated, immersed in hot water for 7 min and 1 min at

65oC in Hillawi, Khadrawi, Hillawi and Khadrawi cultivars, respectively and these were

at par with each other.

4.3.1.4.5 Astringency score


treatments and interaction while cultivars showed non-significant results for astringency

score (Figure 4.67). Maximum astringency scores of 4.16 and 4.16 marked by the

panellist in the fruits those were treated with hot water for 5 min and 3 min at 65oC,

respectively and these were at par with each other. While, minimum astringency score of

1.33 rated by the panellist in the control fruits. The interaction between hot water

treatments and cultivars showed that higher astringency scores (5.00, 4.66, 4.00, 4.00 and

3.66) ranked by the panellist in the fruits those were immersed in hot water for 3 min, 5

min, 7 min, 1min and 5 min in Hillawi, Khadrawi, Khadrawi, Hillawi and Hillawi

137

cultivars, respectively and these were at par with each other. Whereas, minimum

astringency scores of 1.33, 1.33, 1.66 and 2.00 marked by the panellist in the fruits those

were untreated, immersed in hot water for 1 min and 7 min at 65oC in Khadrawi, Hillawi,

Khadrawi and Hillawi, respectively and these were at par with each other.

4.3.1.4.6 Overall acceptability score

The effects of hot water treatments and interaction showed significant differences (p ≤

0.05) while non-significant results were found in cultivars for overall acceptability score

(Figure 4.68). The fruits those were treated with hot water for 5 min and 3 min at 65oC

showed higher overall acceptability scores of 3.83 and 3.50 marked by the panellists,

respectively and these were at par with each other. While, minimum overall acceptability

score of 0.50 ranked by the panellist in the control fruits. The interaction between hot

water treatments and cultivars showed that fruits those were immersed in hot water for 3

min, 5 min and 7 min showed maximum overall acceptability scores of 4.66, 4.33 and

3.66 rated by the panellists in Hillawi and Khadrawi, respectively and these were at par

with each other. Whereas, minimum overall acceptability scores (0.33, 0.66, 1.33 and

1.33) marked by the panellists in the control fruits and immersed in hot water for 1 min at

65oC in Khadrawi, Hillawi, Khadrawi and Hillawi cultivars, respectively and these were

at par with each other.

In general, panellists preferred Hillawi fruits those were immersed in hot water for 3 min

at 65oC and Khadrawi fruits treated with hot water for 5 min at 65

oC over all other

treatments.

138

Figure 4.63 Effects of hot water treatments at 65oC on colour score of Hillawi


Figure 4.64 Effects of hot water treatments at 65oC on taste score of Hillawi and


0

1

2

3

4

5

6C

olo

ur

sco

re


Hillawi Khadrawi

0

1

2

3

4

5

6

Ta

ste

sco

re


Hillawi Khadrawi

139

Figure 4.65 Effects of hot water treatments at 65oC on texture score of Hillawi


Figure 4.66 Effects of hot water treatments at 65oC on firmness score of Hillawi


0

1

2

3

4

5

6T

extu

re s

core


Hillawi Khadrawi

0

1

2

3

4

5

6

Fir

mn

ess

sco

re


Hillawi Khadrawi

140

Figure 4.67 Effects of hot water treatments at 65oC on astringency score of


Figure 4.68 Effects of hot water treatments at 65oC on overall acceptability

score of Hillawi and Khadrawi date palm fruit ± S.E.

0

1

2

3

4

5

6A

strin

gen

cy s

core


Hillawi Khadrawi

-1

0

1

2

3

4

5

6

Ov

era

ll a

ccep

tab

ilit

y s

core


Hillawi Khadrawi

141

4.3.2 Study-3 Effects of different chemicals on the ripening

behaviour and fruit quality of date palm.

4.3.2.1 Results

4.3.2.1.1 Fruit physical traits

4.3.2.1.1.1 Uniform fruit ripening index (%)


regarding the effects of chemical treatments while cultivars and their interaction were

found non-significant regarding uniform fruit ripening index in fruits at tamar stage.

Fruits those were treated with different chemicals progressively increased the index of

uniform fruit ripening as compared to fruits without chemicals in both date palm

cultivars. The fruits those were treated with 3% acetic acid (T3) showed higher uniform

fruit ripening index of 64.24% followed by fruits those were treated with 2% acetic acid

(T2) where uniform fruit ripening index of 55.95% was recorded than all other

treatments. Whereas, minimum uniform fruits ripening index of 14.99% was noted in the

fruits those were untreated (T1). The fruits those were treated with T4 (dipping in 2%

NaCl), T5 (dipping in 3% NaCl), T8 (dipping in 2% acetic acid+2% NaCl+2 ml/L

ethephon) and T9 (dipping in 3% acetic acid+3% NaCl+4 ml/L ethephon) tended to have

an intermediate effect on uniform fruit ripening index of both date palm cultivars.

4.3.2.1.1.2 Fruit weight loss (%)


chemical treatments and cultivars while interaction between them showed non-significant

results for fruit weight loss in fruits at tamar stage (Figure 4.70). Fruits dipped in various

types of chemicals showed progressive decrease in weight loss as compared to untreated

fruits. Minimum weight loss of 15.06% was recorded in the fruits those were treated with

3% acetic acid (T3) followed by 2% acetic acid (T2) where weight loss of 17.70% was

noted in the fruits. Whereas, maximum losses in weights of 29.20, 28.73 and 28.65%

were noted in the fruits those were untreated, dipped in 2 ml/L ethephon (T6) and 4 ml/L

(T7) ethephon, respectively and these were at par with each other. The Hillawi fruits

showed higher loss in weight (24.56%) as compared to the fruits of Khadrawi where loss

in weight of 23.51% was recorded. The intermediary effect was noted in fruits those were

treated with T4 (dipping in 2% NaCl), T5 (dipping in 3% NaCl), T8 (dipping in 2% acetic

142

acid+2% NaCl+2 ml/L ethephon) and T9 (dipping in 3% acetic acid+3% NaCl+4 ml/L

ethephon) regarding the fruit weight loss of both date palm cultivars.

4.3.2.1.1.3 Fruit moisture content (%)

The effects of chemical treatments and cultivars were found significant (p ≤ 0.05) while

interaction between them showed non-significant results for moisture contents in fruits at

tamar stage (Figure 4.71). Fruit moisture contents decreased progressively as well as fruit

goes to ripening. The fruits those were treated with 2% acetic acid (T2) and 3 % acetic

acid (T3) showed higher moisture contents of 24.71 and 24.23, respectively and these

were at par with each other than all other treatments. Whereas, minimum moisture

contents of 15.73% were noted in the fruits those were without chemical treatments (T1).

The fruits of Khadrawi showed higher level of moisture contents (20.86%) as compared

to the fruits of Hillawi where moisture contents of 20.02% were noted. The fruits those

were treated with T8 (dipping in 2% acetic acid+2% NaCl+2 ml/L ethephon) and T9

(dipping in 3% acetic acid+3% NaCl+4 ml/L ethephon) tended to have an intermediate

effect on fruit moisture contents of both date palm cultivars.

4.3.2.1.1.4 Fruit flesh weight (g)



results for flesh weight in fruits at tamar stage (Figure 4.72). Higher flesh weights of 4.34

and 4.00 g were noted in the fruits those were treated with 3 % acetic acid and 2% acetic

acid, respectively and these were at par with each other than all other chemicals

treatments. While, lower flesh weights of 3.22, 3.23, 32.28, 3.40, 3.40 and 3.57 g were

recorded in the fruits those were untreated, 2 ml/L ethephon, 3% acetic acid+3% NaCl+4

ml/L ethephon (T9), 2% acetic acid, 2% NaCl, 2 ml/L ethephon, 4 ml/L ethephon (T8)

and 2% NaCl, respectively and these were at par with each other. The Khadrawi fruits

showed higher flesh weight (3.68 g) than the fruits of Hillawi where flesh weight of 3.68

g was measured.

4.3.2.1.1.5 Fruit pit weight (g)

The analysed data presented in Figure 4.73 showed statistically non-significant

differences (p ≥ 0.05) regarding the effects of chemical treatments and interaction while a

significant difference was found in cultivars for pit weight in fruits at tamar stage. The

Hillawi fruits shoed higher pit weight (0.64 g) as compared to the fruits of Khadrawi

where pit weight of 0.59 g was measured.

143

Figure 4.69 Effects of different chemicals on uniform fruit ripening index (%) of

Hillawi and Khadrawi date palm fruit after incubation at 40±1oC for 72 h

± S.E.

(T1=control, T2=dipping in 2% acetic acid, T3=dipping in 3% acetic acid,

T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6=dipping in 2 ml/L

ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic acid+2%

NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3% NaCl+4 ml/L

ethephon)

Figure 4.70 Effects of different chemicals on uniform fruit weight loss (%) of Hillawi

and Khadrawi date palm fruit after incubation at 40±1oC for 72 h ± S.E.



ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in 2% acetic

acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+3%

NaCl+4 ml/L ethephon)

0

10

20

30

40

50

60

70

80

T1 T2 T3 T4 T5 T6 T7 T8 T9

Un

iform

fru

it r

ipen

ing

in

dex

(%

)

Hillawi Khadrawi

0

5

10

15

20

25

30

35

T1 T2 T3 T4 T5 T6 T7 T8 T9

Fru

it w

eig

ht

loss

(%

)

Hillawi Khadrawi

144

Figure 4.71 Effects of different chemicals on fruit moisture content (%) of Hillawi and

Khadrawi date palm fruit after incubation at 40±1oC for 72 h ± S.E.






Figure 4.72 Effects of different chemicals on fruit flesh weight (g) of Hillawi and







0

5

10

15

20

25

30

T1 T2 T3 T4 T5 T6 T7 T8 T9

Mo

istu

re c

on

ten

t (%

)

Hillawi Khadrawi

0

1

2

3

4

5

T1 T2 T3 T4 T5 T6 T7 T8 T9

Fru

it f

lesh

wei

gh

t (g

)

Hillawi Khadrawi

145

Figure 4.73 Effects of different chemicals on fruit pit weight (g) of Hillawi and







4.3.2.2.1 Fruit biochemical traits

4.3.2.2.1.1 Total soluble solids concentration (oBrix)


chemical treatments and cultivars while their interaction showed non-significant results

for total soluble solids concentration in fruit at tamar stage (Figure 4.74). Total soluble

solid concentration increased with the progression of fruit ripening at tamar stage. The

fruits those were treated with 3% acetic acid (T3) showed higher amounts of total soluble

solids concentration (10.71 oBrix) as compared to the fruit of all other treatments.

Whereas, lower total soluble solids concentration of 6.58 oBrix were noted in the fruits

those were untreated (T1). The Hillawi fruits showed higher total soluble solids

concentration (8.56 oBrix) than the fruits of Khadrawi where total soluble solids contents

of 7.95 oBrix were recorded. The fruits those were treated with T4 (dipping in 2% NaCl)

and T5 (dipping in 3% NaCl) tended to have an intermediate effect on total soluble solid

concentration of both date palm cultivars.

4.3.2.2.1.2 Total titratable acidity (%)

The effects of chemical treatments and cultivars were found significant while interaction

between them showed non-significant results for total titratable acidity in fruits at tamar

stage (Figure 4.75). The fruits those were treated with 3% acetic acid showed lower level

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

T1 T2 T3 T4 T5 T6 T7 T8 T9

Fru

it p

it w

eig

ht

(g)

Hillawi Khadrawi

146

of total titratable acidity (0.118%) followed by 2% acetic acid (T3) where titratable

acidity of 0.135% was recorded than all other chemical treatments. While, higher value of

total titratable acidity (0.207%) was noted in the fruits those were untreated (T1). The

fruits of Hillawi showed lower level of total titratable acidity (0.161%) than the Khadrawi

fruits where total titratable acidity of 0.169% was recorded. The fruits those were treated

with T4 (dipping in 2% NaCl) and T5 (dipping in 3% NaCl) tended to have an

intermediate effect on total titratable acidity of both date palm cultivars.

4.3.2.2.1.3 Ascorbic acid (mg 100 g-1

)

Ascorbic acid in fruit at tamar stage showed significant differences at p ≤ 0.05 regarding

the effects of chemicals treatments and cultivars while non-significant results were found

in their interaction (Figure 4.76). Maximum amounts of ascorbic acid (0.916 and 0.883

mg 100 g-1

) were noted in the fruits those were treated with 3% acetic acid (T3) and 2%

acetic acid (T2) and those were at par with each other than all other chemical treatments.

While, lower ascorbic acid of 0.733 mg 100 g-1

were noted in the control fruit (T1) and

these were at par with the fruit of T7 (4 ml/L ethephon, T9 (3% acetic acid+3% NaCl+4

ml/L ethephon and T6 (2 ml/L ethephon) where ascorbic acid were 0.766, 0.777 and

0.790 mg 100 g-1

, respectively and these were at par with each other. The Hillawi fruit

showed higher level of ascorbic acid (0.834 mg 100 g-1

) as compared to the fruit of

Khadrawi where ascorbic acid of 0.793 mg 100 g-1

was recorded. The fruits those were

treated with T4 (dipping in 2% NaCl) and T5 (dipping in 3% NaCl) tended to have an

intermediate effect on ascorbic acid of both date palm cultivars.

147

Figure 4.74 Effects of different chemicals on total soluble solids (oBrix) of Hillawi and







Figure 4.75 Effects of different chemicals on total titratable acidity (%) of Hillawi and







0

2

4

6

8

10

12

T1 T2 T3 T4 T5 T6 T7 T8 T9

TS

S (

oB

rix)

Hillawi Khadrawi

0

0.05

0.1

0.15

0.2

0.25

T1 T2 T3 T4 T5 T6 T7 T8 T9

Aci

dit

y (

%)

Hillawi Khadrawi

148

Figure 4.76 Effects of different chemicals on ascorbic acid (mg 100 g-1

) of Hillawi and







4.3.2.2.1.4 Glucose (%)


regarding the effects of chemical treatments and cultivars while interaction between them

was found non-significant for glucose in fruit at tamar stage. Higher glucose contents of

29.06% were recorded in the fruits those were treated with 3% acetic acid (T3) followed

by 2% acetic acid (T2) where glucose were 27.03% than all other treatments. Whereas,

lower amounts of glucose contents (19.60 and 20.55%) were noted in the fruits those

were untreated and dipped in 4 ml/L ethephon solutions (T7), respectively and these were

at par with each other. The Hillawi fruits showed higher glucose (24.16%) than the fruits

of Khadrawi where glucose of 22.70% were recorded. The intermediary effect was noted

in fruits those were treated with T4 (dipping in 2% NaCl), T5 (dipping in 3% NaCl), T8

(dipping in 2% acetic acid+2% NaCl+2 ml/L ethephon) and T9 (dipping in 3% acetic

acid+3% NaCl+4 ml/L ethephon) regarding the glucose of both date palm cultivars.

4.3.2.2.1.5 Fructose (%)



results for fructose in fruit at tamar stage (Figure 4.78). The fruits those were treated with

0

0.2

0.4

0.6

0.8

1

1.2

T1 T2 T3 T4 T5 T6 T7 T8 T9

Asc

orb

ic a

cid

(m

g 1

00

g-1

)

Hillawi Khadrawi

149

3% acetic acid (T3) showed higher amounts of fructose (27.11%) followed by 2% acetic

acid (T2) where fructose of 25.56% was noted than all other chemical treatments. While,

lower fructose of 17.71% were recorded in the fruits those were untreated (T1). The fruits

of Hillawi showed higher fructose (22.51%) as compared to the fruits of Khadrawi where

fructose of 21.53% was recorded. The fruits those were treated with T8 (dipping in 2%

acetic acid+2% NaCl+2 ml/L ethephon) and T9 (dipping in 3% acetic acid+3% NaCl+4

ml/L ethephon) tended to have an intermediate effect on fruit fructose of both date palm

cultivars.

4.3.2.2.1.6 Sucrose (%)

The effects of chemical treatments and cultivars were found significant while interaction

between them showed non-significant results for sucrose in fruit at tamar stage (Figure

4.79). Higher sucrose contents of 3.19% were noted in the fruits those were treated with

3% acetic acid (T3) followed by 2% acetic acid (T2) where sucrose were 2.89% than all

other chemical treatments. Whereas, lower values of sucrose (1.92, 2.09 and 2.15%) were

noted in the fruits of T1 (control), T9 (3% acetic acid+3% NaCl+4 ml/L ethephon) and T8

(2% acetic acid+2% NaCl+2 ml/L ethephon), respectively and these were at par with each

other. The Hillawi fruit showed higher sucrose (2.56%) as compared to the fruit of

Khadrawi where sucrose contents of 2.30% were noted. The intermediary effect was

noted in fruits those were treated with T4 (dipping in 2% NaCl), T5 (dipping in 3%

NaCl), T8 (dipping in 2% acetic acid+2% NaCl+2 ml/L ethephon) and T9 (dipping in 3%

acetic acid+3% NaCl+4 ml/L ethephon) regarding the sucrose of both date palm cultivars.

4.3.2.2.1.7 Reducing sugars (%)

Reducing sugars in fruit at tamar stage showed statistically significant differences (p ≤

0.05) regarding the effects of chemicals treatments and cultivars while their interaction

was found non-significant (Figure 4.80). The fruits those were treated with 3% acetic acid

(T3) showed higher amounts of reducing sugars (56.18%) followed by 2% acetic acid

(T2) where reducing sugars were 52.59% than all other chemical treatments. Meanwhile,

minimum reducing sugar contents of 37.32% were noted in the fruits those were untreated

(T1). The Hillawi fruits showed higher reducing sugars (46.67%) as compared to the fruits

of Khadrawi where reducing sugars of 44.23% were noted. The fruits those were treated

with T8 (dipping in 2% acetic acid+2% NaCl+2 ml/L ethephon) and T9 (dipping in 3%

acetic acid+3% NaCl+4 ml/L ethephon) tended to have an intermediate effect on fruit

reducing sugars of both date palm cultivars.

150

4.3.2.2.1.8 Total sugars (%)



was found non-significant for total sugars in fruit at tamar stage (Figure 4.3.2.2.1.8).

Maximum total sugar contents of 59.38% were recorded in the fruits those were treated

with 3% acetic acid (T3) followed by 2% acetic acid (T2) where total sugars were 55.48%

than all other chemical treatments. Whereas, minimum amounts of total sugars (39.25%)

were noted in the control fruits (T1). The fruit of Hillawi showed higher total sugars

(49.24%) as compared to the fruits of Khadrawi where total sugars of 46.54% were

recorded. The intermediary effect was noted in fruits those were treated with T4 (dipping

in 2% NaCl), T5 (dipping in 3% NaCl), T8 (dipping in 2% acetic acid+2% NaCl+2 ml/L

ethephon) and T9 (dipping in 3% acetic acid+3% NaCl+4 ml/L ethephon) regarding the

total sugars of both date palm cultivars.

Figure 4.77 Effects of different chemicals on glucose (%) of Hillawi and Khadrawi date

palm fruit after incubation at 40±1oC for 72 h ± S.E.






0

5

10

15

20

25

30

35

T1 T2 T3 T4 T5 T6 T7 T8 T9

Glu

cose

(%

)

Hillawi Khadrawi

151

Figure 4.78 Effects of different chemicals on fructose (%) of Hillawi and Khadrawi date





acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+ 3%


Figure 4.79 Effects of different chemicals on sucrose (%) of Hillawi and Khadrawi date







0

5

10

15

20

25

30

35

T1 T2 T3 T4 T5 T6 T7 T8 T9

Fru

cto

se (

%)

Hillawi Khadrawi

0

0.5

1

1.5

2

2.5

3

3.5

4

T1 T2 T3 T4 T5 T6 T7 T8 T9

Su

cro

se (

%)

Hillawi Khadrawi

152

Figure 4.80 Effects of different chemicals on reducing sugars (%) of Hillawi and





acid+2% NaCl+2 ml/L ethephon, T9=dipping in 3% acetic acid+ 3%


Figure 4.81 Effects of different chemicals on total sugars (%) of Hillawi and Khadrawi

date palm fruit after incubation at 40±1oC for 72 h ± S.E.






0

10

20

30

40

50

60

70

T1 T2 T3 T4 T5 T6 T7 T8 T9

Red

uci

ng

su

ga

rs (

%)

Hillawi Khadrawi

0

10

20

30

40

50

60

70

T1 T2 T3 T4 T5 T6 T7 T8 T9

To

tal

sug

ars

(%

)

Hillawi Khadrawi

153

4.3.2.3.1 Fruit phytonutritional traits

4.3.2.3.1.1 Total phenolics (mg GAE/100 g)

Total phenolics in fruit at tamar stage showed significant differences (p ≤ 0.05) regarding

the effects of chemical treatments and cultivars while interaction between them was found

non-significant (Figure 4.82). Higher amounts of total phenolics (248.83, 245.18 and

234.28 mg GAE/100) were recorded in fruit of T3 (3% acetic acid), T2 (2% acetic acid)

and T4 (2% NaCl), respectively and these were at par with each other. While, lower total

phenolics of 208.50, 215.39 and 216.22 mg GAE/100 g were noted in the fruit of T1

(control), T6 (2 ml/L ethephon) and T7 (4 ml/L ethephon), respectively and these were at

par with each other. The fruit of Khadrawi showed higher total phenolic contents (233.48

mg GAE/100 g) than the fruit of Khadrawi where total phenolics of 222.80 mg GAE/100

g were recorded.

4.3.2.3.1.2 Total flavonoids (mg CEQ/100 g)



was found non-significant for total flavonoids in fruit at tamar stage. The fruits those

were treated with 3% acetic acid (T3) and 2% acetic acid (T2) showed higher values of

total flavonoids (27.27 and 26.82 mg CEQ/100 g), respectively and these were at par with

each other. While, lower total flavonoids of 21.73, 21.80, 21.81, 22.82, 22.84 and 23.29

mg CEQ/100 g were noted in the fruit of T1 (control), T9 (3% acetic acid+3% NaCl+4

ml/L ethephon), T8 (2% acetic acid+2% NaCl+2 ml/L ethephon), T6 (2 ml/L ethephon),

T5 (3% NaCl) and T7 (4 ml/L ethephon), respectively and these were at par with each

other. The Hillawi fruit showed higher total flavonoids (24.42 mg CEQ/100 g) as

compared to the fruit of Khadrawi where total flavonoids of 22.71 mg CEQ/100 g were

recorded.

4.3.2.3.1.3 Total tannins (%)

Statistically significant results were found at p ≤ 0.05 regarding the effects of chemicals

treatments and cultivars while their interaction showed non-significant differences for

total tannins in fruit at tamar stage (Figure 4.84). Lower amounts of total tannins (0.196,

0.200 and 0.215% were recorded in the fruit of T3 (3% acetic acid), T4 (2% NaCl) and

T2 (2% acetic acid), respectively and these were at par with each other. Whereas, higher

total tannins of 0.339 and 0.328% were recorded in the fruits of T1 (control) and T9 (3%

acetic acid+3% NaCl+4 ml/L ethephon), respectively and these were at par with each

154

other. The fruit of Hillawi showed lower total tannins (0.252%) than the fruit of Khadrawi

where total tannins of 0.281% were noted.

4.3.2.3.1.4 Total antioxidants (%)

Total antioxidants in the fruit at tamar stage showed significant differences (p ≤ 0.05)


was found non-significant (Figure 4.85). Higher antioxidants of 61.39 and 56.49% were

noted in the fruits of T3 (3% acetic acid) and T2 (2% acetic acid), respectively and these

were at par with each other. While, lower antioxidants activities (48.02, 51.27, 51.28,

52.68, 52.80 and 52.95%) were noted in the fruits of T1 (control), T6 (2 ml/L ethephon),

T9 (3% acetic acid+3% NaCl+4 ml/L ethephon), T8 (2% acetic acid+2% NaCl+2 ml/L

ethephon), T4 (2% NaCl) and T5 (3% NaCl), respectively and these were at par with each

other. The Khadrawi fruits showed higher antioxidants activities (54.71%) as compared to

the fruits of Hillawi where total antioxidants activities of 52.25% were recorded.

Figure 4.82 Effects of different chemicals on total phenolics (mg GAE/100 g) of Hillawi







0

50

100

150

200

250

300

T1 T2 T3 T4 T5 T6 T7 T8 T9

TP

C (

mg

GA

E/1

00

g)

Hillawi Khadrawi

155

Figure 4.83 Effects of different chemicals on total flavonoids (mg CEQ/100 g) of Hillawi







Figure 4.84 Effects of different chemicals on total tannins (%) of Hillawi and Khadrawi



T4=dipping in 2% NaCl, T5=dipping in 3% NaCl, T6= dipping in 2 ml/L




0

5

10

15

20

25

30

35

T1 T2 T3 T4 T5 T6 T7 T8 T9

TF

C (

mg

CE

Q/1

00

g)

Hillawi Khadrawi

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

T1 T2 T3 T4 T5 T6 T7 T8 T9

To

tal

tan

nin

s (%

)

Hillawi Khadrawi

156

Figure 4.85 Effects of different chemicals on total antioxidants (%) of Hillawi and




ethephon, T7=dipping in 4 ml/L ethephon, T8=dipping in % acetic acid+2%


ethephon)

4.3.2.4.1 Fruit organoleptic traits

4.3.2.4.1.1 Colour score

The analysed data presented in Figure 4.86 showed significant results (p ≤ 0.05)

regarding the effects of chemical treatments while cultivars and interaction showed non-

significant differences for colour score. Maximum colour score index of 4.33 was marked

by the panellist in the fruits those were treated with 3% acetic acid (T3) followed by 2%

acetic acid (T2) where colour score index was 3.50 ranked by the panellists than all other

chemical treatments. While, minimum colour score indexes of 1.83, 1.83, 2.16, 2.33 and

2.33 were marked by the panellists in the fruits of T1 (control), T9 (dipping in 3% acetic

acid+ 3% NaCl+4 ml/L ethephon), T7 (4 ml/L ethephon), T8 (dipping in 2% acetic acid+

2% NaCl+2 ml/L ethephon) and T6 (2 ml/L ethephon), respectively and these were at par

with each other. The intermediary effect was noted in fruits those were treated with T4

(dipping in 2% NaCl) and T5 (dipping in 3% NaCl) regarding the colour score of both


4.3.2.4.1.2 Taste score


chemical treatments while cultivars and interaction showed non-significant differences

0

10

20

30

40

50

60

70

T1 T2 T3 T4 T5 T6 T7 T8 T9

Tota

l an

tiox

idan

ts (

%)

Hillawi Khadrawi

157

for taste score (Figure 4.87). The fruits those were treated with 3% acetic acid (T3)

showed higher index of taste score (4.33) marked by the panellists followed by 2% acetic

acid (T2) where taste score was 3.50 ranked by the panellists. While, minimum taste

scores indexes of 1.83, 1.83, 2.16, 2.33 and 2.33 were rated by the panellists in the fruits

of T1 (control), T9 (dipping in 3% acetic acid+ 3% NaCl+4 ml/L ethephon), T7 (4 ml/L

ethephon), T8 (dipping in 2% acetic acid+ 2% NaCl+2 ml/L ethephon) and T6 (2 ml/L

ethephon), respectively and these were at par with each other.

4.3.2.4.1.3 Texture score

Effects of chemicals treatments showed significant differences (p ≤ 0.05) while non-

significant results were found in cultivars and interaction on texture scores in the fruits at

tamar stage (Figure 4.88). Maximum values of texture scores (4.66 and 3.83) were ranked

by the panellist in fruits of T3 (3% acetic acid) and T2 (2% acetic acid), respectively and

these were at par with each other. Whereas, minimum texture scores indexes of 1.50,

2.16, 2.16 and 2.33 were marked by the panellists in the fruits of T1 (control), T9

(dipping in 3% acetic acid+ 3% NaCl+4 ml/L ethephon), T7 (4 ml/L ethephon) and T6 (2

ml/L ethephon), respectively and these were at par with each other.

4.3.2.4.1.4 Firmness score

Firmness scores in the fruits at tamar stage showed significant (p ≤ 0.05) results regarding

the effects of chemical treatments while non-significant differences were found in

cultivars and interaction (Figure 4.89). Higher firmness score index of 4.83 marked by the

panellists was noted in the fruits those were treated with 3% acetic acid (T3) followed by

the fruits of T2 and T4 where firmness indexes were 4.00 and 3.50, respectively and these

were at par with each other. While, minimum firmness scores (1.16 and 1.50) were rated

by the panellist in the fruits of T1 (control) and T9 (dipping in 3% acetic acid+ 3%

NaCl+4 ml/L ethephon), respectively and these were at par with each other. The

intermediary effect was noted in fruits those were treated with T4 (dipping in 2% NaCl)

and T5 (dipping in 3% NaCl) regarding the firmness score of both date palm cultivars.

4.3.2.4.1.5 Astringency score

Statistically significant results were found regarding the effects of chemical treatments

while cultivars and interaction showed non-significant differences for astringency scores

in fruits at tamar stage (Figure 4.90). Maximum astringency score index of 4.83 marked

by the panellists was received in the fruits those were treated with 3% acetic acid (T3)

followed by fruits those were dipped in 2% acetic acid (T2) where astringency score was

3.83 rated by the panellists than the fruits of all other treatments. Whereas, minimum

158

astringency score indexes (1.16, 1.33 and 1.83) were marked by the panellists in the fruits

of T1 (control), T9 (dipping in 3% acetic acid+ 3% NaCl+4 ml/L ethephon) and T7 (4

ml/L ethephon), respectively and these were at par with each other.

4.3.2.4.1.6 Overall acceptability score


regarding the effects of chemical treatments while cultivars and interaction were found

non-significant for overall acceptability scores in fruits at tamar stage (Figure 4.3.2.4.1.6).

Maximum overall acceptability score of 4.83 was marked by the panellist in the fruits

those were treated with 3% acetic acid (T3) than all other treatments. Meanwhile,

minimum overall acceptability scores indexes of 1.16, 1.33 and 1.83 were ranked by the

panellists in the fruits of T1 (control), T9 (dipping in 3% acetic acid+ 3% NaCl+4 ml/L

ethephon) and T7 (4 ml/L ethephon).

In general, panellists favoured the fruits of both Hillawi and Khadrawi cultivars those

were dipped in 3% acetic acid (T3) after incubation at 40±1oC for 72h as compared to the

fruits of all other chemical treatments.

Figure 4.86 Effects of different chemicals on colour score of Hillawi and Khadrawi date






ethephon)

0

1

2

3

4

5

T1 T2 T3 T4 T5 T6 T7 T8 T9

Co

lou

r sc

ore

Hillawi Khadrawi

159

Figure 4.87 Effects of different chemicals on taste score of Hillawi and Khadrawi date






ethephon)

Figure 4.88 Effects of different chemicals on texture score of Hillawi and Khadrawi






ethephon)

0

1

2

3

4

5

T1 T2 T3 T4 T5 T6 T7 T8 T9

Ta

ste

sco

re

Hillawi Khadrawi

0

1

2

3

4

5

6

T1 T2 T3 T4 T5 T6 T7 T8 T9

Tex

ture

sco

re

Hillawi Khadrawi

160

Figure 4.89 Effects of different chemicals on firmness score of Hillawi and Khadrawi






ethephon)

Figure 4.90 Effects of different chemicals on astringency score of Hillawi and Khadrawi






ethephon)

0

1

2

3

4

5

6

T1 T2 T3 T4 T5 T6 T7 T8 T9

Fir

mn

ess

sco

re

Hillawi Khadrawi

0

1

2

3

4

5

6

T1 T2 T3 T4 T5 T6 T7 T8 T9

Ast

rin

gen

cy s

core

Hillawi Khadrawi

161

Figure 4.91 Effects of different chemicals on astringency score of Hillawi and Khadrawi






ethephon)

0

1

2

3

4

5

6

T1 T2 T3 T4 T5 T6 T7 T8 T9

Ov

era

ll a

ccep

tab

ilit

y s

core

Hillawi Khadrawi

162

4.3.2 (1, 2) Discussion

Climate is one of the main stay in date palm industry, which drastically affects its

cultivation, production, processing and quality. Monsoon rains at rutab and tamar fruit

ripening stages are threatening issues for date palm growers and processors. According to

an estimate about 60% of the dates are destroyed due these rains. In the country there is

no trend to process or cure the fruit of Hillawi and Khadrawi cultivars and whole the fruit

is consumed at khalal stage as fresh dates or convert into fully dried form (Chohara) with

less economic value. However, if these dates are artificially processed or cured into semi

dry form or as soft dates by harvesting the fruit at khalal stage before the onset of

monsoon rains, losses occurred due to these rains can be minimized and good return

could be earned. The present study therefore was conducted to explore or find out the

various ways or means to artificially ripe the date fruit by harvesting at early stage of

maturity (khalal stage) to avoid the risk of monsoon rains. This whole study was

comprised of three parts which are discussed in separate paragraphs as follows.

Heat treatments of fruits and vegetables can be done by means of hot water, vapor, or hot

dry air. Recently, extensive global concern in the heat treatment for maintaining the food

quality and diseases has been shown in literatures. Water is the most efficient and

preferred medium in many of the applications than the others. Hot water treatment has

some advantages which include: comparatively simple to use, short treatment time,

consistent handling of fruits and water temperatures, and killing of skin-borne decay

causing agents with economic advantage as it is cheap as compared to other heat

application methods (Fallik et al., 1999; Garcia-Jimenez et al., 2004). Higher temperature

exposure in agricultural products alters the various physiological processes such as heat

shock proteins transcripts and different level of proteins in such type of products (Lurie,

1998).

Fruit ripening is a natural process which involves a number of physiological and chemical

changes in which fruits gradually becomes sweet in taste, more coloured, and becomes

softer and palatable. However, with the progression of science and technology, numerous

artificial methods have been observed for fruit ripening generally to fulfill the demands of

consumers’ and other economic factors. In date palm, the need of artificial ripening is

encountered to avoid the risk of monsoon rains at the time of fruit harvesting or ripening.

The present study therefore was carried out to explore the role of different chemicals on

fruit ripening behavior and quality of Hillawi and Khadrawi date palm cultivars.

163

Different types of chemicals or ripening agents are available which possibly disrupt the

epidermal cells and the protoplasm, thereby releasing and activating the enzymes.

Ripening by involvement of enzymes like invertase, polygalacturonase, cellulase, pectin

esterase and polyphenol oxidases, causes the disturbance in structural parts e.g. pectin and

cellulose that hold cells together, to become soluble, and the tannins to precipitate. As a

result, this facilitates the ripening process of fruits from khalal to tamar, which involve;

precipitating out of tannins, increasing small sugars causing sweetness, texture softening

and introducing changes in fruit colour and other ripening-associated quality parameters.

The extent of modification varies which depends on the stage of fruit maturity and

environmental factors that are responsible for the ripening/curing of the fruits (Shamshiri,

and Rahemi, 1999).

In the present study, hot water treatments significantly affected the fruit physical,

biochemical and phytonutritional traits in date fruits at tamar stage as compared to fruits

those were untreated in both date palm cultivars. Both cultivars showed variable response

regarding the effects of hot water treatments. Hot water treatments for 3 and 5 min at

65oC significantly accelerated the fruit ripening processes and produced more uniformly

ripe fruits as compared to untreated fruit in Hillawi and Khadrawi, respectively. In date

the actual mechanism by which hot water treatments accelerated the fruit ripening

processes in not yet known but it might be due to increased rate of respiration, ethylene

synthesis and formation of cell wall degrading enzymes. These findings are supported by

different coworkers who reported that heat treatments significantly affects the various

ripening processes such as fruit colour (Cheng et al, 1988; Tian et al., 1996), ethylene

production (Ketsa et al., 1999), rate of respiration (Inaba and Chachin, 1988), firmness of

fruits, breakdown of cell wall (Lurie and Nussinovich, 1996) and formation of different

volatile compounds (McDonald et al, 1999). Our results are in agreement with

Shahnawaz et al. (2012) who reported that in mango hot water treated fruits ripened

earlier as compared to the fruits those were without hot water treatments with higher

scores of organoleptic properties marked by the panellists. The results are also supported

by findings of Jacobi et al., (2001) who reported that heat treatment accelerates the

yellowing of the mango fruit skin and also promotes the uniformity in skin colour and in

most cultivars fruit becomes softer. The actual mechanism by which heat treatment

accelerated date palm fruit ripening is not yet known but it has been hypothesized that it

is associated with increased synthesis of carotenoid, degradation of chlorophyll and

synthesis of cell wall degrading enzymes. Fruits those were treated with higher

164

temperature of 7 min duration at 65oC showed gradual increase in weight loss, reduced

moisture contents with lower fruit flesh and pit weights as compared to fruits those were

treated in hot water for short duration. These findings are supported by Lurie and Klein

(1990) who reported that the heat treatments triggered the increase in respiration rate and

a significant amount of organic acids were used as a substrate during respiration and

metabolic processes.

In the present study, different chemicals (acetic acid, NaCl, ethephon) significantly

affected the ripening processes and quality of both date palm cultivars as compared to

untreated fruits. Different chemicals such as 3% acetic acid and 2% acetic acid showed

better results for obtaining the higher uniform fruit ripening index with good quality and

sensorial properties as compared to fruits those were treated with other chemicals. These

results are supported by Saleem et al. (2005) who reported that acetic acid and sodium

chloride are more effective for uniform fruit ripening acceleration, as these chemicals

inclined to makes ripening by triggering the modifications in the selected quality

characters in Dhakki date palm. They reported that that sodium chloride is more effective

for inducing ripening but our results are opposite to them that acetic acid is more effective

for uniform ripening and good quality fruits in Hillawi and Khadrawi date palm. These

results are in agreement with Tafti and Fooladi (2006) who postulated that treatment of

‘Mozafati’ date fruits with acetic acid at the end of khalal stage after incubating at 38-

40oC for 3-5 days is the more effective and economical method for artificial ripening of

the fruit. These results are also correlated with Haq (1990) who reported that curing of

‘Zahidi’ dates with acetic acid and NaCl alone or in combination showed significantly

superior results by affecting the early ripening of the fruit and make the fruit soft over all

other treatments. The possible reason for ripening acceleration in date fruits due to such

type of chemicals might be that polygalacturonase and cellulase are the ripening enzymes

which are absent at immature stage but their activity was increased during ripening

(Hasegawa et al., 1969; Saleem et al., 2002). Untreated fruits do not ripe properly and

most of the fruits remained immature and goes to shrivelling and puffiness with higher

fruit weight loss, less moisture contents and less fruit flesh weight with poor quality as

compared to fruits those were treated with different chemicals. It is because; unripe fruits

are not able to develop ripening processes properly as in chemical treated fruits.

Hot water treatments significantly affected the fruit quality and organoleptic attributes in

both date palm cultivars. Hot water treatments for 3 and 5 min in Hillawi and Khadrawi

produced good quality fruits at tamar stage in terms of higher TSS, sugars, phytonutrients

165

and organoleptic properties than longer duration of 7 min, respectively. These findings

are supported by Wall (2004) who reported that hot water exposure time had a greater

effect than the water temperature during banana fruit ripening. It is because; the

conversion of starch into sugars might be reduced at higher temperatures and longer

exposure times. While levels of titratable acidity and ascorbic acid were decreased in

fruits those were treated with hot water in both cultivars as compared to untreated fruits.

The decrease in acidity and ascorbic acid levels might be due to the oxidative destruction

of biochemical constituents during thermal processing when date fruits exposed to hot

water treatments as compared to untreated fruits. These findings were also confirmed by

Pudmini and Prabha (1997) and Thomas and Oke (1980) who reported that hot water

treatments reduced the levels of acidity and ascorbic acid contents during the progression

of fruit ripening. The increase in total soluble solids might be due to the alteration in cell

wall structure and break down of complex carbohydrates into simple sugars whereas slow

changes observed in TSS of control fruit samples (Aina 1990; Rajwana et al., 2010).

Similarly, the increase in total sugars level could be attributed mainly due to the

breakdown of starch into simple sugars during ripening process along with a proportional

increase in total sugars which were attributed to the increased activity of amylase and

other enzymes converted into sucrose, glucose and fructose (Aina 1990; Rajwana et al.,

2010). These results can be correlated with the findings of Srinivasa et al. (2002) and

Kudachikar et al. (2001) who reported that hot water treatments effectively increased the

total sugar contents in mango and fewer changes occurred in control fruits. These results

were also supported by different co-workers Aina (1990) and Jabbar et al. (2010) who

reported that sugar contents were remained higher in hot water treated fruits as compared

to untreated fruits throughout the ripening process.

The fruit quality composition of both cultivars was significantly improved in chemical

treated fruits as compared to untreated fruits. The best quality fruits were obtained from

3% acetic acid and 2% acetic acid than other chemical treatments in both cultivars. Total

soluble solids, sugars, phytonutritional parameters and organoleptic properties were

significantly improved in acetic acid treated fruits. These findings are supported by Mirza

and Meraj-ud-Din (1988) who treated the fruits of ‘Dhakki’ and ‘Basra’ cultivars at

khalal stage with 3% brine solution, 0.25% acetic acid and 0.25% citric acid solution for 5

min and found that different chemical treatments enhanced the fruit ripening process

significantly with better fruit quality. Our results regarding the TSS are in line with Naik

et al. (1993) who reported that increases in TSS during the ripening was mainly due to

166

break down of polysaccharides into simple sugars thereby causing a rise in total soluble

solids. These findings were also supported by different co-workers (Zaid, 2002; Saleem et

al., 2005; Awad, 2007) they reported that significant increase in total soluble solids might

be due to the higher evaporation of water contents in the incubator during the progression

of ripening (Rouhani and Bassiri, 1977; Zaid, 2002; Saleem et al., 2005; Awad, 2007).

These results are also supported by Farahnaky and Afshari-Jouybari (2011) who reported

that fruits those were treated with hot acetic acid solution showed slightly increase in TSS

contents in Mazafati date palm cultivar as compared to untreated fruits. The reduction of

TSS in untreated fruits was probably due to the slow rate of respiration and metabolic

activities, hence retarding the ripening process. These findings were supported by Rohani

et al. (1997) they reported that the slow rate of respiration also slows down the synthesis

and use of metabolites resulting in lower amounts of total soluble solids due to the slower

changes from carbohydrates to sugars. However, the effects of such chemicals on

phytonutrients are not reported in the literature. In our study, the phytonutrients were

significantly affected by different chemicals. It is because, fruits those were treated with

chemicals showed progressive ripening and fruit becomes softer. This might be due to

changes in phenolic compounds and antioxidants activities which affect the fruit quality

composition in date fruits during ripening. However, this mechanism is still unknown in

date fruits and also in other fruits. However, further research is needed to confirm these

changes to understand the actual mechanism.

Hot water treatments at 65oC for duration of 3 and 5 min in Hillawi and Khadrawi

showed good results to accelerate the fruit ripening, uniformity and good quality

attributes, respectively. This research work has a great significance for the date growers

who could harvest the fruit at khalal stage to avoid the risk of monsoon rains and

artificially ripe the fruits by adopting hot water technologies. The results of the current

experiment have a great practical application for the date growers who can artificially ripe

the date fruit by harvesting at khalal stage with the treatments of 3% acetic acid and can

avoid the risk of monsoon rains. In the meantime, uniformity in ripening is an extra

benefit which can be achieved by adopting these technologies and it provides more

economic return to the growers.

167

4.3.3 (1, 2) Conclusion

Hot water treatment (HWT) is an effective and low cast technology to accelerate the date

fruit ripening artificially. Hot water exposures for 3 and 5 min at 65oC in Hillawi and

Khadrawi cultivars showed best results to reduce the fruit ripening period up to 6 days

and produced uniformly ripened fruits (73.33 and 81.66%) with better quality and higher

acceptability of organoleptic scores marked by the panellists as compared to untreated

fruits. Acetic acid (3%) significantly affected the fruit ripening behaviour and quality

composition as compared to other treatments after incubation at 40 ± 1oC for 72 h in

Hillawi and Khadrawi date palm cultivars. Acetic acid (3%) showed higher uniform

ripening index of 64.24% with higher total soluble solids concentration, sugars, total

phenolics, total flavonoids, total antioxidants and organoleptic properties after incubation

at 40±1oC for 72 h. Artificial date fruit ripening reduced the losses occurred due to rains

by harvesting the fruit at early maturity stage (khalal stage).

168

4.4. Study-4 Sun-drying techniques (SDTs) affected the fruit

quality attributes of dates picked at rutab stage cv.

Hillawi.

4.4.1 Results

4.4.1.1 Fruit weight loss (%)


regarding the effects of sun-drying techniques on weight loss in the fruits of Hillawi

cultivars at tamar stage. Different types of sun-drying techniques significantly affected

the fruit weight loss of Hillawi date palm. Minimum weight loss of 18.73% was recorded

in the fruits of SDT4 (DSE with removal in baskets and covered during night) and these

were at par with the fruits of SDT3 (DSE and removal in baskets during night) where loss

in weight was 22.66% followed by SDT5 (DSE and removal with mats during night) and

SDT2 (DSE and covering with polythene sheet during night) where losses in weights

were 27.47 and 28.17%, respectively and these were at par with each other. While,

maximum weight loss of 47.80% was noted in the control fruits of SDT1 (DSE without

covering and removal during night).

4.4.1.2 Fruit moisture content (%)

Statistically significant differences were found at p ≤ 0.05 regarding the effects of sun-

drying techniques on moisture content in the fruits of Hillawi cultivar at tamar stage

(Figure 4.93). Different sun-drying techniques significantly affected the fruit moisture

contents of Hillawi date palm. Maximum level of moisture contents (24.13 and 21.06%)

were recorded in the fruits of SD4 (DSE with removal in baskets and covered during

night) and SDT3 (DSE and removal in baskets during night), respectively and these were

at par with each other. Whereas, lower level of moisture contents (13.91%) was noted in

the fruits of SDT1 (DSE without covering and removal during night).

4.4.1.3 Total soluble solids concentration (oBrix)

The effects of sun-drying techniques showed statistically significant differences for total

soluble solids contents in the fruits of Hillawi at tamar stage (Figure 4.94). Higher

amounts of total soluble solids contents (11.09 oBrix) was noted in the fruits of SD4 (DSE

with removal in baskets and covered during night) followed by SDT3 (DSE and removal

in baskets during night) and SDT5 (DSE and removal with mats during night) where total

soluble solids contents were 9.39 and 8.43 oBrix, respectively and these were at par with

169

each other. While, lower total soluble solids contents of 6.21 oBrix were noted in the

fruits of SD1 (DSE without covering and removal during night) and these were at par

with the fruits of SD2 (DSE and covering with polythene sheet during night) where total

soluble solids contents of 7.28 oBrix were recorded.

4.4.1.4 Total titratable acidity (%)

Total titratable acidity in the fruits at tamar stage showed significant differences at p ≤

0.05 regarding the effects of sun-drying techniques (Figure 4.95). Different types of sun-

drying techniques significantly affected the total titratable acidity of Hillawi fruits. Lower

total titratable acidity of 6.21% was noted in the fruits of SD4 (DSE with removal in

baskets and covered during night) than the fruits of all other treatments. While, higher

total titratable acidity level of 0.263% was recorded in the fruits of SD1 (DSE without

covering and removal during night).

4.4.1.5 Reducing sugars (%)

The analysed data presented in Figure 4.96 showed statistically significant differences (p

≤ 0.05) regarding the effects of sun-drying techniques on the reducing sugars of Hillawi

fruit at tamar stage. Different sun-drying techniques positively affected the reducing

sugars of Hillawi fruit. Higher amounts of reducing sugars (26.46%) were recorded in the

fruits of SD4 (DSE with removal in baskets and covered during night) followed by SD3

(DSE and removal in baskets during night) and SD5 (DSE and removal with mats during

night) where reducing sugars were 47.24 and 44.21%, respectively. Whereas, lower levels

of reducing sugars (26.46%) were noted in the fruit of SD1 (DSE without covering and

removal during night).

4.4.1.6 Total sugars (%)

Statistically significant results were found at p ≤ 0.05 regarding the effects of sun-drying

techniques on the total sugars in fruit at tamar stage (Figure 4.97). Different types of sun-

drying techniques significantly affected the total sugars of Hillawi date palm. Maximum

amounts of total sugars of 69.39% were recorded in the fruits of SD4 (DSE with removal

in baskets and covered during night) followed by SD3 (DSE and removal in baskets

during night) where total sugars of 62.10% were noted as compared to the fruit of all

other sun-drying treatments. Whereas, minimum amounts of total sugars (32.88%) were

noted in the fruit of SD1 (DSE without covering and removal during night).

170

Figure 4.92 Effects of sun-drying techniques on weight loss (%) in the fruit of Hillawi

cultivar analysed at tamar stage ± S.E.

(SDT1 = Control (DSE without covering and removal during night), SDT2 =

DSE and covering with polythene sheet during night, SDT3 = DSE and

removal in baskets during night, SDT4 = DSE with removal in baskets and

covered during night, SDT5 = DSE and removal with mats during night

(SDT= Sun-drying techniques, DSE= Direct sun-light exposure)

Figure 4.93 Effects of sun-drying techniques on moisture content (%) in the fruit of

Hillawi cultivar analysed at tamar stage ± S.E.






0

10

20

30

40

50

60

SDT1 SDT2 SDT3 SDT4 SDT5

Wei

gh

t lo

ss (

%)

0

5

10

15

20

25

30


Mo

istu

re c

on

ten

t (%

)

171

Figure 4.94 Effects of sun-drying techniques on total soluble solids concentration (%) in

the fruits of Hillawi cultivar analysed at tamar stage ± S.E.






Figure 4.95 Effects of sun-drying techniques on total titratable acidity (%) in the fruits of







0

2

4

6

8

10

12

14


TS

S (

oB

rix

)

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35


TA

(%

)

172

Figure 4.96 Effects of sun-drying techniques on reducing sugars (%) in the fruits of







Figure 4.97 Effects of sun-drying techniques on total sugars (%) in the fruits of Hillawi







0

10

20

30

40

50

60


Red

ucin

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ug

ars

(%)

0

10

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40

50

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70

80


To

tal

sug

ars

(%)

173

4.4.1.7 Total phenolics (mg GAE/100 g)


regarding the effects of sun-drying techniques on total phenolics in the fruit of Hillawi

cultivar at tamar stage. Higher amounts of total phenolic contents (224.28 mg GAE/100

g) were recorded in the fruit of SD4 (DSE with removal in baskets and covered during

night) followed by SDT3 (DSE and removal in baskets during night) and SDT5 (DSE and

removal with mats during night) where total phenolics were 189.88 and 181.50 mg

GAE/100 g, respectively. Whereas, lower amounts of total phenolics of 166.80 mg

GAE/100 g were noted in the fruit of SDT1 (DSE without covering and removal during

night).

4.4.1.8 Total flavonoids (mg CEQ/100 g)

Statistically significant differences were found at p ≤ 0.05 regarding the effects of sun-

drying techniques on total flavonoids in the fruit of Hillawi cultivar at tamar stage (Figure

4.99). Maximum amounts of total flavonoids (34.31 mg CEQ/100 g) were noted in the

fruits of SD4 (DSE with removal in baskets and covered during night) followed by SDT3

(DSE and removal in baskets during night) where total flavonoids of 29.86 mg CEQ/100

g were recorded. While, lower amounts of total flavonoids of 22.54 mg CEQ/100 g were

noted in the fruit of SDT1 (DSE without covering and removal during night).

4.4.1.9 Total antioxidants (%)

Total antioxidants activities in fruit at tamar stage showed significant differences (p ≤

0.05) regarding the effects of sun-drying techniques (Figure 4.100). Higher total

antioxidants activities of 72.20% were noted in the fruits of SD4 (DSE with removal in

baskets and covered during night) followed by SDT3 (DSE and removal in baskets during

night) and SDT5 (DSE and removal with mats during night) where total antioxidants

activities were 61.21 and 51.31%, respectively and these were at par with each other.

Whereas, lower total antioxidants activities of 32.35% were recorded in the fruits of

SDT1 (DSE without covering and removal during night).

4.4.1.10 Total tannins (%)

The effects of sun-drying techniques showed significant differences (p ≤ 0.05) for total

tannins in Hillawi fruit at tamar stage (Figure 4.101). Lower total tannins of 0.143% were

recorded in the fruit of SD4 (DSE with removal in baskets and covered during night)

followed by SDT3 (DSE and removal in baskets during night) where total tannin contents

of 0.210% were noted. Whereas, higher amounts of total tannins of 0.323% were

recorded in the fruit of SDT1 (DSE without covering and removal during night).

174

Figure 4.98 Effects of sun-drying techniques on total phenolics (mg GAE/100 g) in the

fruits of Hillawi cultivar analysed at tamar stage ± S.E.






Figure 4.99 Effects of sun-drying techniques on total flavonoids (mg CEQ/100 g) in the

fruits of Hillawi cultivar analysed at tamar stage ± S.E.






0

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TP

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175

Figure 4.100 Effects of sun-drying techniques on total antioxidants (%) in the fruits of


(SDT1 = Control (DSE without covering and removal during night), SDT2

= DSE and covering with polythene sheet during night, SDT3 = DSE and




Figure 4.101 Effects of sun-drying techniques on total tannins (%) in the fruits of Hillawi


(SDT1 = Control (DSE without covering and removal during night), SDT2

= DSE and covering with polythene sheet during night, SDT3 = DSE and




0

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80


To

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0

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0.1

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176

4.4.2 Discussion

Dates are an important fruit crop of Pakistan and its consumption is started at khalal stage

but if these are consumed at tamar stage (dried) then its return can be increased up to four

fold. Hillawi is the main cultured variety of Punjab and almost consumed at khalal stage.

Hillawi is the prime cultivar and commercially grown in Punjab, Pakistan and its ripening

period starts from mid-July to August which is a peak monsoon period. The fruit of

Hillawi is completely harvested and consumed at khalal stage with less economic worth

and there is no trend to process or cure the fruit due to the occurrence of monsoon rains.

However, if the fruit is harvested at its right maturity stage (rutab) and properly

processed/cured by using proper sun drying techniques (SDTs), fruit can be saved for

future consumption with good economic value.

Drying is an ancient process of food preservation that works by removing water from the

food, which inhibits enzymatic degradation and limits microbial growth (Ratti, 2001). It

is the most wide spread and energy-consuming food preservation process (Ratti, 2001).

Different methods of drying have been developed for foods and each method has its own

characteristics. Sun-drying is a low cast technology which reduces the post-harvest losses

in developing countries. Drying of fresh dates is necessary because it contains high

moisture (about 60%) which limits the shelf life. In sun-drying water is usually removed

by evaporation. Mature date fruits are allowed to partially dry on the trees before they are

harvested and further sun dried to enhance their keeping quality and storage. However,

problems associated with sun drying are well documented (Guine and Castro, 2002;

Doymaz, 2004; Doymaz, 2005). During dehydration, irreversible burst and discoloration

occur to the exposed commodity resulting in loss of integrity due to capillaries shrinkage

with less hydrophilic properties (Lewicki, 1998). Sun-drying allows flavours to

concentrate, prevents the loss of volatile compounds and unwanted caramelization of

natural sugars which may result from using other drying methods (Valley, 2000). Sun-

drying enhances good initial color and texture, as well as translucency and sheen (Mrak et

al., 1946).

Fruit weight loss and moisture contents were greatly affected by various sun drying

techniques. Maximum loss in fruit weight (47.80%) was recorded in control (DSE

without covering and removal during night) whereas minimum fruit weight loss (18.73%)

was observed in SDT4 (DSE with removal in baskets and covered during night).

Maximum reduction in moisture (13.91%) was noted in control while minimum reduction

177

(24.13%) was recorded in SDT4. Weight loss from fresh food commodity is mainly due

to transpiration and respiration. In transpiration water is lost due to differences in water

vapour pressure in the atmosphere and the transpiring surface. Respiration results weight

reduction because a carbon atom is lost from the fruit each time a carbon-dioxide

molecule is produced from an absorbed oxygen molecule and evolved into the

atmosphere (Bhowmik and Pan, 1992). Fruit weight loss of the fresh product can

influence the economic returns. It was observed that continuous open sun drying caused

excessive weight loss with poor quality fruit as compared to other modified sun drying

techniques. In developing countries, one of the main purposes of sun drying is to reduce

the postharvest losses by lowering the internal water contents to an optimum level

(Olorunda et al., 1990).

Sugars in date fruits are the most important constituents as they provide a rich and quick

source of energy to human beings. Sun drying techniques significantly affected the total

soluble solids (TSS) in Hillawi fruit. Minimum TSS value (6.21 oBrix) was noted in

control while higher value (11.09 oBrix) was recorded in SDT4. Higher fruit acidity

(0.263%) was recorded in control whereas lower acidity level (0.130%) was recorded in

treatment SDT4. Higher value of total sugar (69.39%) was recorded in SDT4 while

SDT1 gave minimum total sugar contents of 32.88%. Maximum reducing sugar content

(51.47%) was noted in SDT4 followed by SDT3 and SDT5 whereas minimum value was

recorded in SDT1 which was 26.46%. Solar radiation and temperature have a great

influence on fruit sugar accumulation. The results regarding sugar contents were

significantly affected by sun drying techniques. Fruit sugar content is a variable

multigenic trait which is greatly affected under varied environmental conditions (Kader,

1986). The open sun drying caused a heavy loss of sugar contents as compared to those

fruits which were removed during night time. High temperature led to increase the TSS

due to changes in carbohydrate biosynthetic enzymes activity (Walker and Ho, 1977), and

increased transpiration (Gautier et al., 2008). Postharvest practices such as timing of the

harvest, handling techniques, and storage conditions can alter the fruit sugar profiling

(Kader, 1986). In SDT4 the improvement in fruit quality might be due to presence of all

day’s heat which reduces the excessive fruit weight loss by maintaining the internal fruit

water contents, color and other quality related characters.

Date fruit is an important source of phytonutrients that are responsible for sustaining the

human life; they have been recognized as containing properties for disease prevention.

Different types of sun drying techniques significantly affected the phytonutritional

178

composition of the Hillawi fruit. Higher total phenolic contents were measured in SDT4

which were 224.28 mg GAE/100 g and lower TPC (166.80 mg GAE/100 g) were

recorded in SDT1. Higher antioxidant activity was recorded in SDT4 with greater

scavenging activity of 72.20% DPPH inhibition while lower antioxidant activity was

observed in SDT1 with scavenging activity of 32.35% DPPH inhibition. Maximum total

flavonoids contents (TFC) were recorded in SDT4 which were 34.31 mg CEQ/100 g.

Lower TFC was observed in SDT1 which gave the value of 22.54 mg CEQ/100 g.

Higher level of total tannin contents (0.323%) were noted in control while minimum were

recorded in SDT4 which were 0.143% followed by SDT3 (0.210%) and SDT5 (0.246%).

Our results are also in line with (Walker and Ho, 1977) who reported that appropriate

sun-drying methods allows food flavours to concentrate, preventing the loss of volatile

compounds and unwanted caramelization of natural sugars and prevents the undesirable

browning color. These results are also in agreement with (Mrak et al., 1946) who

revealed that sun-drying enhances the good initial color and texture, as well as

translucency and sheen of the tested food commodity. In our study phenolic compounds

were also significantly affected by various sun drying techniques. These results are

supported by findings of (Al Farsi et al., 2005) they reported that sun drying significantly

increased phenolic contents in fruits that could be due to the degradation of tannins by

heat, destruction of anthocyanin and maturation of enzymes during the drying process

(Maillard and Berset, 1995).

4.4.3 Conclusion

The obtained results indicate that sun drying techniques (SDTs) significantly affected the

fruit physical and quality characters in ‘Hillawi’ date palm. Among all the tested sun


good which plays a very effective role in reducing the excessive fruit weight loss by

maintaining the fruit moisture contents to an optimum level and other compositional

changes such as TSS, acidity, total sugar, reducing sugar, total phenolics, total antioxidant

activity, total flavonoids and total tannin contents.

179

Harvesting of rutab dates Drying on mat

Removal in baskets After removal in baskets

Covered in baskets with newspaper Dates after washing

180

Dates packed in box Dates packed in box with labelling

Slide-4.3: Different steps involved in the processing of soft Hillawi dates by sun-

drying techniques.

181

Chapter-5

General discussion: Conclusions: Recommendations

5.1 General discussion

Globally, date palm is one of the most extensively cultivated fruit crops in dry regions

and playing an important role in the history of mankind since ancient times. The date

palm is particularly significant in scorched areas and the economic and social life of the

peoples living in such areas is fully dependent on date’s income. The nutritional value of

date fruit consumed either fresh or in the form of many other derived by-products has a

unique global importance. Climate is one of the main stay in date palm industry, which

drastically affects its cultivation, production, processing and quality. In Pakistan, the peak

production period of dates begins during hot months of July and August. But

unfortunately, monsoon rains occurs during these months which is a real threat for date

fruit crop because these rains can destroy up to 60% date fruit.

Fruit ripening is an irreversible phenomenon which involves a number of physical,

biochemical and organoleptic changes. These changes are interdependent on each other

and after the successful completion of these changes fruit becomes edible with desirable

quality traits. Exogenous applications of some chemicals are capable to alter these

changes by accelerating the rate of respiration, starch hydrolysis, softening, and flavour

and colour development. A very little work has been reported regarding the on-tree and

off-tree fruit ripening acceleration and few references are available in the literature where

efforts have been made to accelerate the fruit ripening on the tree and after harvest by

adopting different ways or means.

The foremost goal of this whole study was to minimize the losses occurs due to monsoon

rains at the time of fruit harvesting or ripening in Hillawi and Khadrawi date palm

cultivars. This study was comprised of four parts: in first part the effectiveness of

ethephon to accelerate the fruit ripening and quality was studied at two different fruit

maturity stages (final kimri and early khalal). Second part of the study comprised of

different strands thinning practices to accelerate the fruit maturation period and quality.

Third part of the study consists of two experiments: first one was to evaluate the role of

hot water treatments on ripening and fruit quality of date palm. In second one the role of

different chemicals on the ripening behaviour and fruit quality of date palm was

182

investigated. In the fourth and last study, effects of different sun-drying techniques on the

fruit quality characteristics of Hillawi date palm were studied.

In first part of the study ethephon was applied at final kimri and early khalal fruit maturity

stages by two different methods (spray and injection). Foliar spray of ethephon applied at

both fruit maturity stages (final kimri and early khalal) showed better results as compared

to injection application method in both date palm cultivars. Foliar application of ethephon

@ 6 ml/L and 4 ml/L at final kimri and early khalal stages accelerated the fruit ripening

period by about 13 and 6 days from final kimri to rutab stage, respectively with higher

rutab fruit yield per bunch and maximum uniform fruit ripening index. The increase in

rutab fruit yield per bunch and uniform fruit ripening index were mainly due to the action

of ethylene that generates from ethephon application. Current results regarding the fruit

physical traits (fruit weight, fruit length, fruit width, fruit flesh weight, fruit pit weight)

showed statistically non-significant (p ≥ 0.05) differences against ethephon application

while both date palm cultivars differ significantly and these differences were mainly due

to the genetic character of both cultivars. Foliar spray (6 ml/L and 4 ml/L) at final kimri

and early khalal fruit stages showed more reduction in moisture content in both cultivars.

This decline in fruit moisture content was might be due to the progression of ripening

process due the action of ethylene. Fruit treated with foliar spray (4 ml/L and 2 ml/L) at

final kimri and early khalal stages showed higher total soluble solids concentration in

both cultivars. This increase in total soluble solids concentration in ethephon treated fruits

is might be due to the rise of sugar content which mostly depends upon the conversion of

starch on hydrolysis during the progression of ripening. Foliar application of ethephon (4

ml/L and 2 ml/L) at final kimri and early khalal fruit stages significantly decreased the

level of fruit acidity in both date palm cultivars during both years. The reduction in fruit

acidity indicated that ethephon promoted the ripening process and lowered down the

acidity level due to the completion of ripening processes. Foliar spray of ethephon (4

ml/L and 2 ml/L) at final kimri and early khalal stages significantly increased the ascorbic

acid contents in treated fruits as compared to control fruits. The increase in ascorbic acid

in ethephon treated fruit might be due to quick ripening process and fruits have less time

to loss the ascorbic acid. Foliar spray of ethephon (4 ml/L) at final kimri stage produced

higher sugars in both date palm cultivars. More accumulation of phytonutrients was

observed in ethephon-treated fruit as compared to untreated one in both date palm

cultivars. Ethephon application (4 ml/L) showed higher amounts of total phenolics, total

flavonoids and total antioxidants activities with lower level of total tannins in both

183

cultivars. However, ethephon application at early khalal stage did not show significant

variation except total tannin contents in the fruits of both cultivars. This reduction in fruit

astringency might be due to the coagulation of tannin cells into insoluble tannins in both

cultivars. In general, method of ethephon application showed great variation in their

response as ethephon applied by foliar spray performed better as compared to injection

application in both date palm cultivars. It is because foliar spray might have a direct

contact with fruits cuticle layer that fasten up the respiration process and fruits reached at

maturity within shorter time. Whereas, ethephon application by injection could not

achieved quick and fast response that might be due to its slow translocation from the

peduncle to individual fruit strands.

Cluster thinning has an important role in plants to induct physiological adjustments by

improving the kinetics of fruits maturation. It is because thinning improves the sanitary

conditions under the canopy and allows more light and fresh air penetration in the

remaining fruit clusters (Smithyman et al., 1998). In the current study, strands thinning

significantly reduced the fruits maturation period as compared to fruit where no thinning

was applied in both date palm cultivars. Strands thinning intensity @ 30% RCS + 30%

STT and 30% RCS alone accelerated the fruit maturity processes and shortened the

period by about 10 days from early kimri to rutab stage. Strands thinning intensity @

30% RCS + 30% STT and 30% RCS alone showed higher rutab fruit yield per bunch and

greater uniform fruit ripening index in both the date palm cultivars. It is due to the

involvement of more light penetration and air circulation within the fruit bunches which

might leads to fast and uniformly ripe fruits. It is because fruits received nutrients and

water from the main stem through peduncle for the development of tissue or to gain

proper size. Strands thinning intensity (30% RCS + 30% STT) and (30% RCS alone)

significantly improved the fruit physical traits such as fruit weight, fruit length, fruit

width and flesh weight in both date palm cultivars. The reasons are same as explained

above but some other can also strengthen these reasons. Sun light exposure is also

important to regulate the metabolism of carbon and assimilates in young growing fruits.

In contrast, control fruits (without thinning) had less light exposure due to high density

that leads the reduced sink strength and fruits could not develop their growth properly.

Strands thinning intensity (30% RCS + 30% STT) and (30% RCS alone) showed higher

total soluble solids concentration, ascorbic acid, sugars and decreased the level of acidity

in thinned fruit as compared to fruit without thinning. Fruit phytonutrients (total

phenolics, total flavonoids and total antioxidants) were significantly improved and total

184

tannins were decreased by strands thinning treatments in both date palm cultivars during

both years. The main reason is more exposure of light due to less fruits density; it is

because light plays an important role in processes which are responsible for the

accumulation of anthocyanins and phenolic compounds (Wicks and Kliewer, 1983,

Dokoozlian and Kliewer, 1996). On the other hand, un-thinned fruits could not attain

proper return due to less availability of light or air circulation that affects the rate of

photosynthetic carbon assimilation rate (Morrison and Noble, 1990).

Hot water treatment has some advantages which include: comparatively simple to use,

short treatment time, consistent handling of fruits and water temperatures, and killing of

skin-borne decay causing agents with economic advantage as it is cheap as compared to

other heat application methods (Fallik et al., 1999; Garcia-Jimenez et al., 2004). Different

types of chemicals or ripening agents are available which possibly disrupt the epidermal

cells and the protoplasm, thereby releasing and activating the enzymes. Ripening by the

involvement of enzymes like invertase, polygalacturonase, cellulase, pectin esterase and

polyphenol oxidases, causes the disturbance in structural parts such as pectin and

cellulose that hold cells together, to become soluble, and the tannins to precipitate.

In the present study, hot water treatments significantly affected the fruit physical,

biochemical and phytonutritional traits in date fruits at tamar stage as compared to fruits

those were untreated in both date palm cultivars. Hot water treatments for 3 and 5 min at

65oC significantly accelerated the fruit ripening processes and produced more uniformly

ripe fruits as compared to untreated fruit in Hillawi and Khadrawi, respectively. In date

fruits the actual mechanism by which hot water treatments accelerated the fruit ripening

processes is still unknown but it might be due to the increased rate of respiration, ethylene

synthesis and formation of cell wall degrading enzymes. Different chemicals (acetic acid,

NaCl, ethephon) also significantly affected the ripening processes and quality of both date

palm cultivars as compared to untreated fruits. Different chemicals such as acetic acid

(3%) and acetic acid (2%) showed better results for obtaining the higher uniform fruit

ripening index with good quality and sensorial properties as compared to fruits those were

treated with other chemicals. It is because polygalacturonase and cellulase are the

ripening enzymes which remained very low or absent in immature fruits but their activity

increased during the progression of ripening (Hasegawa and Maier, 1980; Saleem et al.,

2002) so it could be possible that exogenous application of such ripening agents enhanced

the activity of these enzymes as they become active and showed desired response.

Untreated fruits do not ripe properly and most of the fruits remained immature and goes

185

to shrivelling and puffiness with higher fruit weight loss, less moisture contents and less

fruit flesh weight with poor quality as compared to fruits those were treated with different

chemicals. It is possible that untreated fruits could not initiate their desired processes due

the lack of ripening enzymes therefore due higher weight loss fruit goes to shrivelling and

puffiness.

Hot water treatments significantly affected the fruit quality and organoleptic attributes in

both date palm cultivars especially hot water treatments for 3 and 5 min in Hillawi and

Khadrawi produced good quality fruits at tamar stage in terms of higher TSS, sugars,

phytonutrients and organoleptic properties as compared to the fruits treated for longer

exposure time of 7 min. It is because the fruits treated for longer exposure of 7 min

remained in higher temperature for a long period, so due to high temperature starch could

not hydrolyse into sugars properly. The levels of titratable acidity and ascorbic acid were

decreased in the fruits treated with hot water as compared to untreated fruits in both date

palm cultivars. This decrease in acidity and ascorbic acid might be due to the degradation

of bio-chemical constituents during the fruit ripening. The fruit quality composition of

both cultivars was significantly improved in chemical treated fruit as compared to

untreated fruit. The best quality fruits were obtained from 3% acetic acid and 2% acetic

acid than other chemical treatments in both cultivars. Total soluble solids, sugars,

phytonutritional parameters and organoleptic properties were significantly improved in

acetic acid treated fruits. The phytonutrients were significantly affected by different

chemicals treatments. It is because, fruits those were treated with chemicals showed

progressive ripening and fruit becomes softer as compared to untreated fruits. This might

be due to changes in phenolic compounds and antioxidants activities during the

progression of ripening which affects the fruit quality composition during ripening.

However, this mechanism is still unknown in date fruits and also in other fruits.

Therefore, further research is needed to confirm these changes to understand the actual

mechanism. In the last study, different sun-drying techniques (SDTs) were used for the

curing of soft Hillawi dates. Sun-drying techniques significantly affected the fruit

physical and biochemical characters in Hillawi date palm. Among all the tested sun-


good which plays a very effective role in reducing the excessive fruit weight loss by

maintaining the fruit moisture contents to an optimum level and other compositional

changes such as TSS, acidity, total sugar, reducing sugar, total phenolics, total

antioxidants, total flavonoids and lower level of total tannins.

186

5.2 Conclusions

1. Foliar application of ethephon (4 ml/L) at final kimri stage is an effective cultural

practice for Hillawi and Khadrawi date palm cultivars to combat the seasonal

fluctuations in the form of monsoon rains at the time of fruit harvesting and/or

ripening by accelerating the fruit maturation period about 13 days, attained

uniformity index of 60.46%, rutab fruit yield (6.29 kg) per bunch and also

improved the fruit quality composition in terms of TSS, ascorbic acid, sugars,

total phenolics, total flavonoids and total antioxidants with decreased level of

acidity and total tannins in both date palm cultivars.

2. Strands thinning intensity (30% RCS alone) resulted in 10 days early maturity and

higher yield (5.22 kg per bunch) and uniformly ripe fruits (76.28%) at rutab stage

in Hillawi and Khadrawi cultivars. The TSS, ascorbic acid, sugars (glucose,

fructose, and sucrose), total phenolics, total flavonoids and total antioxidants were

significantly improved while titratable acidity and total tannin contents were

decreased in thinned fruits. Strands thinning intensities (30% RCS alone) was the

best thinning treatment for obtaining the desired fruit quality traits as compared to

other thinning intensities.

3. Hot water exposures for 3 and 5 min at 65oC in Hillawi and Khadrawi cultivars

showed best results to reduce the fruit ripening period up to 6 days and produced

uniformly ripened fruits (73.33 and 81.66%) with better quality and higher

acceptability of organoleptic scores marked by the panellists as compared to

untreated fruits.

4. Acetic acid (3%) showed higher uniform ripening index of 64.24% with higher

levels of TSS, sugars, total phenolics, total flavonoids, total antioxidants and

organoleptic properties after incubation at 40 ± 1oC for 72 h.

5. Among different sun drying techniques, SDT4 (DSE with removal in baskets and

covered during night) proved best regarding the fruit quality composition such as

TSS, acidity, total sugar, reducing sugar, total phenolics, total antioxidants, total

flavonoids and total tannins.

5.3 Recommendations

1. Ethephon should be applied as foliar spray (4 ml/L) at final kimri stage is effective

to reduce the fruit harvesting period up to 13 days to avoid synchronization of

monsoon rains as well as improving the fruit ripening and quality of date palm.

187

2. If pesticide companies are involved to commercialize this ethylene releasing

product (ethephon) at farm level then the losses occurred due to monsoon rains

can be minimized by reducing the fruit transition period from kimri to rutab fruit

developmental stages by early harvesting and processing the fruit.

3. Growers can obtain uniformly mature and good quality fruits by adopting regular

thinning practices (30% RCS alone) as managerial approach to attain maximum

uniformity and good fruit physical, biochemical and phytochemical characters.

4. Date palm growers can artificially ripe/cure the date fruits by applying hot water

treatments for short duration (3 min for Hillawi and 5 min for Khadrawi at 65oC)

and by dipping the fruit in 3% acetic acid solution by harvesting the fruit at early

maturation phase (khalal stage) to avoid the risk of monsoon rains.

5. Date palm growers can cure the Hillawi date fruit by adopting sun drying

techniques such as SDT4 (DSE with removal in baskets and covered during night)

with good fruit quality composition and can get maximum return.

4.5 Future research needed

Ethephon application should be applied on various other commercially grown date palm

cultivars to avoid the synchronization of monsoon rains as well as improving the fruit

ripening and quality. More research work is needed to investigate the response of

ethephon at genetic and molecular level to dissect the biochemistry and physiology of

ethylene production from pre-harvest application of ethephon. There is a need to measure

the detrimental effects of various fruit ripening agents. To explore the complete

nutritional profile of date fruit at various maturity stages with respect to ethylene

synthesis and carbon dioxide production. There is a need to create awareness among the

date palm growers about the quality processing of soft and/or semi dried dates by

replacing the fully dried date’s technology (Chohara formation) with higher economic

return and more nutritional value. For this purpose Government and Private sector should

be involved at national level to boost up the dates processing industry and post-harvest

handling.

188

LITERATURE CITED

A.O.A.C. 1980. Official Methods of Analysis. Association of Analytical Chemists.

Arlington, USA.

Abdelhak, M., E. Guendez, K. Eugene and P. Kefalas. 2005. Phenolic profile and

antioxidant activity of the Algerian ripe date palm fruit (Phoenix dactylifera).

Food Chem., 89: 411-420.

Abdel-Hamid, N. 2000. Effect of time, rate and patterns of thinning, leaf bunch ratio and

male type on “Zaghloul” date yield and quality. Arab. J. Agric. Sci., 8: 305-

317.

Abdel-Latif, S.A. 1988. The physiology of ripening of date palm fruit (Phoenix

dactylifera L.). M.Sc. Diss., Univ. Baghdad, Iraq.

Abdul, A. and A. Allaith. 2008. Antioxidant activity of Bahraini date palm (Phoenix

dactylifera L.) fruit of various cultivars. Int. J. Food Sci. Technol., 43: 1033-

1040.

Abeles, F.B., P.W. Morgan and M.E. Saltveit. 1992. Ethylene in plant biology, vol. 15,

2nd ed. Academic Press, San Diego, California.

Ahmed, A., A.W. Ahmed and R.K. Robinson. 1995. Chemical composition of date

varieties as influenced by the stage of ripening. Food Chem., 54: 305-309.

Aina, J.O. 1990. Physico-chemical changes in African Mango (Irvingia gabonensis)

during normal storage ripening. Food Chem., 36: 205-12.

Ainsworth, A.A. and K.M. Gillespie. 2007. Estimation of total phenolic content and other

oxidation substrates in plant tissues using Folin-Ciocalteu reagent. Nature, 4:

875-877.

Akl, A.M., M.A. Ragab and A.Y. Mohamed. 2004. Yield and fruit quality of Sewy date

palms in response to some fruit thinning treatments. Second International

Conference on Date Palm. El-Arish, Egypt, 6-8 Oct.

Al Farsi, M.A. and C.Y. Lee. 2008. Nutritional and functional properties of dates: a

review. Critical Rev. Food Sci. Nutr., 48: 877-887.

Al-Darwish, Z.S.B.A. 2010. Effect of the fruit thinning on the date palm fruit shrivels of

the Ghar cultivar. Fourth International Conference on Date Palm. Abu Dhabi,

U.A.E., 15-17 March. P. 63.

Alexander, L. and D. Grierson. 2002. Ethylene biosynthesis and action in tomato: a model

for climacteric fruit ripening. J. Exp. Bot., 53: 2039-2055.

189

Al-Farsi, M., C. Alasalavar, A. Morris, M. Baron and F. Shahid, 2005a. Compositional

and sensory characteristics of three native sun-dried date (Phoenix dactylifera

L.) varieties grown in Oman. J. Agric. Food Chem., 53: 7586-7591.

Al-Farsi, M., C. Alasalvar, A. Morris, M. Baron and F. Shahidi. 2005b. Comparison of

antioxidant activity, anthocyanins, carotenoids, and phenolics of three native

fresh and sun-dried date (Phoenix dactylifera L.) varieties grown in Oman. J.

Agric. Food Chem., 53: 7592-7599.

Al-Farsi, M., C. Alasalvar, M. Al-Abid, K. Al-Shoaily, M. Al-Amry and F. Al-Rawahy.

2007. Compositional and functional characteristics of dates, syrups, and their

by-products. Food Chem.. 104: 943-947.

Al-Ghamdi, A.S., O.A. Al-Tahir and A.A. Al-Khateeb. 1993. Thinning stage effects on

fruit size, yield and fruit quality of date palm (Phoenix dactylifera L.) Cv.

Khalas. Third Symposium on date palm, Saudi Arabia, Book of Abstracts, P:

88.

Al-Hooti, S., J.S. Sidhu and H. Qabazard. 1995. Studies on the physico-chemical

characteristics of date fruits of five U.A.E. cultivars at different stages of

maturity. Arab Gulf J. Sci. Res., 13: 553-569.

Al-Hooti, S., J.S. Sidhu and H. Qabazard. 1997. Physicochemical characteristics of five

date fruit cultivars grown in the United Arab Emirates. Plant Food Hum. Nutr.,

50: 101-113.

Al-Hooti, S.N., J.S. Sidhu, J.M. Al-Saqer and A. Al-Othman. 2002. Chemical

composition and quality of date syrup as affected by pectinase/cellulase

enzyme treatment. Food Chem., 79: 215-220.

Ali-Dinar, H.M., A.A. Alkhateeb, I. Al. Abdulhadi, A. Alkhateeb, K.A. Abugulia and

G.R. Abdulla. 2002. Bunch thinning improves yield and fruit quality of date

palm (Phoenix dactylifera L.). Egypt. J. Appl. Sci., 17(11): 228-238.

Ali-Mohamed, A.Y. and A.S.H. Khamis. 2004. Mineral ion content of the seeds of six

cultivars of Bahraini date palm (Phoenix dactylifera L.). J. Agric. Food Chem.,

52: 6522-6525.

Al-Jasim, H.A. and K.S. Al-Delaimy. 1972. Pectinesterase activity of some Iraqi dates at

different stages of maturity. J. Sci. Food Agric., 23: 915-917.

Al-Kahtani, H.A., H.M. Abu-Tarboush, Y.N. Al-Dryhim, M.A. Ahmed, A.S. Bajaber,

E.E. Adam, and M.A. El-Mojaddidi. 1998. Irradiation of dates: insect

190

disinfestation, microbial and chemical assessments, and use of

thermoluminescence technique. Radiat. Phys. Chem., 53: 181-187.

Al-Khateeb, A.A. and H.M. Ali-Dinar. 2002. Date Palm in Kingdom of Saudi Arabia:

Cultivation, Production and Processing. Translation, authorship and publishing

Centre, King Faisal University, Kingdom of Saudi Arabia. P. 188.

Allaith, A.A.A. 2008. Antioxidant activity of Bahraini date palm (Phoenix dactylifera L.)

fruit of various cultivars. Int. J. Food Sci. Technol., 43: 1033-1040.

Al-Mughrabi, M.A., M.A. Bacha and A.O. Abdelrahman. 1989. Influence of pre-harvest

application of ethrel and 2, 4-D on fruit quality. J. King Saud Univ. Agri. Sci.,

1: 95-102.

Al-Noimi, J. and G. Al-Amir. 1980. Physiology and morphology of date palm. Al-Basra

University, Iraq: Faculty of Agriculture.

Al-Obeed, R.S., M.A. Harhash and N.S. Fayez. 2005. Effect of bunch thinning on yield

and fruit quality of Succary date palm cultivar grown in the Riyadh region. J.

King Saud Univ. Agri. Sci., 2: 235-249.

Al-Qarawi, A.A., B.H. Ali, S.A. Al-Mougy and H.M. Mousa. 2003. Gastrointestinal

transit in mice treated with various extracts of date (Phoenix dactylifera L.). J.

Food Chem. Toxicol., 41: 37-39.

Al-Qarawi, A.A., H. Abdel-Rahman, B.H. Ali, H.M. Mousa and S.A. El-Mougy. 2005.

The ameliorative effect of dates (Phoenix dactylifera L.) on ethanol-induced

gastric ulcer in rats. J. Ethno-pharmacology, 98: 313-317.

Al-Qarni, S.S.M. 2005. Biochemical changes during date palm fruits ripening. MSc.

Thesis of science in biochemistry. Faculty of science. King Saud University.

Riyadh, Saudi Arabia, P. 147.

Al-Rawahi, A.S., S. Kasapis and I.M. Al-Bulushi. 2005. Development of a date

confectionary: Part 1. Relating formulation to instrumental texture. Intr. J. Food

Prop., 8: 457-468.

Al-Shahib, W. and R.J. Marshall. 2003. The fruit of the date palm: its possible use as the

best food for the future? Int. J. Food Sci. Nutr., 54: 247-259.

Al-Wasfy, M.M. and R.A.A. Mostafa, 2008. Effect of different methods of fruit thinning

on Zaghloul date palm production and fruit quality. Assiut. J. Agric. Sci., 39:

97-106.

Amira, E.A., E.B. Saafi, B. Mechri, L. Lahouar, M. Issaoui, M. Hammami and L. Achour.

2012. Effects of the ripening stage on phenolic profile, phytochemical

191

composition and antioxidant activity of date palm fruit. J. Agric. Food Chem.,

60: 10896-10902.

Amoros, A., M.T. Pretel, M.S. Almansa, M.A. Botella, P.J. Zapata and M. Serrano. 2009.

Antioxidant and nutritional properties of date fruit from Elche Grove as

affected by maturation and phenotypic variability of date palm. Food Sci.

Technol. Int., 15: 65-72.

Anderson, J.L. 1968. New chemical may aid mechanical harvesting of sour cherries. Utah

Sci., 29: 111-113.

Armitage, A.M. 1989. Promotion of fruit ripening of ornamental peppers by ethephon.

HortScience, 24: 962-964.

Arora, J.S., R.N. Pal and J.S. Jawanda. 1973. Effect of ethrel on degreening of Valencia

sweet orange (C. sinensis Osbeck). Punjab Hort. J., 13: 13-17.

ASF. 2010. Date palm Protection Project Report. Lahore, Pakistan.

Asif, M. 2012. Physico-chemical properties and toxic effect of fruit-ripening agent

calcium carbide. Ann. Trop. Med. Public, 5: 150-156.

Asif, M.I. and O.A. Al Taher. 1983. Ripening of Khasab dates by sodium chloride and

acetic acid. Date Palm J., 2: 121-128.

Awad, M.A. 2007. Increasing the rate of ripening of date palm fruit (Phoenix dactylifera

L.) cv. Helali by preharvest and post-harvest treatments. Post-harvest Biol.

Technol. 43: 121-127.

Awad, M.A. and A. de Jager. 2002. Formation of flavonoids, especially anthocyanin and

chlorogenic acid in „Jonagold‟ apple skin: influences of growth regulators and

fruit maturity. Sci. Hort., 93: 257-266.

Awad, M.A., A.D. Al-Qurashia and S.A. Mohamed. 2011. Antioxidant capacity,

antioxidant compounds and antioxidant enzyme activities in five date cultivars

during development and ripening. Sci. Hort., 129: 688-693.

Bacha, M.A., T.A. Nasr and M.A. Shaheen. 1987. Changes in Physical and Chemical

Characteristics of the Fruits of Four Date Palm Cultivars. Proc. Saudi Biol.

Soc., 10: 285-295.

Bal, J.S., G.S. Bajwa and S.N. Singh. 1996. Role of ethephon in inducing early ripening

and marketing of ber (Zizyphus mauritiana Lamk). Indian J. Hort., 53: 38-41.

Bal, J.S., P.S. Kahlon, J.S. Jawanda and S.S. Sandhu. 1992. Effect of pre-harvest spray on

growth regulators at turning stage on the maturity of ber fruits (Ziziphus

mauritiana Lamk.). Acta Hort., 321: 318-325.

192

Baliga, M.S., B.R.V. Baliga, S.M. Kandathil, H.P. Bhat and P.K. Vayalil. 2011. A review

of the chemistry and pharmacology of the date fruits (Phoenix dactylifera L.).

Food Res. Int., 44: 1812-1822.

Baloch, M.K., S.A. Saleem, K. Ahmad, A.K. Baloch and W.A. Baloch. 2006. Impact of

controlled atmosphere on the stability of Dhakki dates. Swiss Soci. Food Sci.

Technol., 39: 671-676.

Ban, T., M. Kugishima, T. Ogata, S. Shiozaki, S. Horiuchi and H. Ueda. 2007. Effect of

ethephon (2-chloroethylphosphonic acid) on the fruit ripening characters of

rabbit eye blueberry. Sci. Hort., 112: 278-281.

Barreveld, W.H. 1993. Date palm Products. Food and Agriculture Organization of the

United Nations, Agricultural Services Bulletin no.101, Food and Agriculture

Organization of the United Nations, Rome, Italy.

Barrow, S. 1998. A monograph of Phoenix dactylifera L. Kew Bul., 53: 513-575.

Bassal, M.A. and M.D. El-Deeb. 2002. Effect of thinning and some growth regulators on

yield and fruit quality of Zaghloul date palm. Zagazig J. Agric. Res., 29: 1815-

1837.

Batal, K.M. and D.M. Granberry. 1982. Effects of growth regulators on ripening and

abscission of pimiento and paprika peppers. Hort. Sci., 17: 944-946.

Bauza, E. 2002. Date palm kernel extract exhibits antiaging properties and significantly

reduces skin wrinkles. Int. J. Tissue Reac., 24: 131-136.

Beaudry, R.M. and S.J. Kays. 1988. Effect of ethylene source on abscission of pepper

plant organs. Hort. Sci., 23: 742-744.

Behseresht, R., R. Khademi and P. Bayat. 2007. The effect of bunch thinning methods on

quality and quantity of date palm cv. Kabakab. Fourth Symposium on Date

palm. Al-Hassa, Saudi Arabia, 5-8 May.

Belarbi, A., C. Aymard, J.M. Meot, A. Themelin and M. Reynes. 2000. Water desorption

isotherms for eleven varieties of dates. J. Food Eng., 43: 103-107.

Ben-yehoshua, S., S. Iwahori and J.M. Lyons. 1970. Role of ethylene and ethrel in the

development of fig fruit. Israel J. Agric. Res., 22: 173-177.

Besbes, S., C. Blecker, C. Deroanne, N.E. Drira and H. Attia. 2004. Date seeds: chemical

composition and characteristic profiles of the lipid fraction. Food Chem., 84:

577-584.

Bhowmik, S.R. and J.C. Pan. 1992. Shelf life of mature green tomatoes stored in

controlled atmosphere and high humidity. J. Food Sci., 57: 948-953.

193

Biglari, F. 2009. Assessment of antioxidant potential of date (Phoenix dactylifera L.)

fruits from Iran, effect of cold storage and addition to minced chicken meat;

MSc. Thesis. School of Industrial Technology. University of Sains Penang,

Malaysia, P. 15-105.

Biglari, F., A.F.M. AlKarkhi and A.M. Easa. 2008. Antioxidant activity and phenolic

content of various date palm (Phoenix dactylifera L.) fruits from Iran. Food

Chem., 107: 1636-1641.

Blanke, M.M. and A. Leyhe. 1987. Stomatal activity of the grape berry cv. „Riesling‟,

„Muller-Thurgau‟ and „Ehrenfelser‟. J. Plant Physiol., 127: 451-460.

Bonora, E., D. Stefanelli and G. Costa. 2013. Nectarine Fruit Ripening and Quality

Assessed Using the Index of Absorbance Difference (𝐼AD). Int. J. Agron., 1-9.

Booij, I., G. Piombo, J.M. Risterucci, M. Coupe, D. Thomas and M. Ferry. 1992. Study

on the chemical composition of dates at different stages of maturity for the

varietial characterization of various cultivars of date palm (Phoenix dactylifera

L.). Fruits, 47: 667-678.

Brady, C.J. 1987. Fruit ripening. Annual Rev. Plant Physiol., 38: 155-178.

Brar, J.S., H.S. Dhaliwal and J.S. Bal. 2012. Influence of paclobutrazol and ethephon on

fruit quality of „Allahabad Safeda‟ Guava. HortFlora Res. Spec., 1: 135-138.

Brown, S.C., and B.G. Coombe. 1985. Solute accumulation by grape pericarp cells. III.

Sugar changes in vivo and the effect of shading. Biochem. Physiol., 180: 371-

381.

Bubola, M., Ð. Peršurić and K. Ganić. 2011. Impact of cluster thinning on productive

characteristics and wine phenolic composition of cv. Merlot. J. Food Agric.

Environ., 9: 36-39.

Carillo, L.A., F. Ramirez-Bustamante, F.B. V. Torres, R. Rojas- Villegas and E.M. Yahia

2000. Ripening and quality changes in mango fruits as affected by coating with

an edible film. J. Food Quality, 23: 479-86.

Çelikel, F.G., K. Kaynas, S. Özelkök, and U.U.M.L Ertan. 1997. Effects of ethephon on

fruit development and ripening of the fig (Ficus carica L.) variety "bursa

siyahi". Acta Hort., 441: 145-152.

Chaira, N., M.I. Smaali, M. Martinez-Tomé, A. Mrabet, M.A. Murcia, and A. Ferchichi.

2009. Simple phenolic composition, flavonoid contents and antioxidant

capacities in water–methanol extracts of Tunisian common date cultivars

(Phoenix dactylifera L.). Int. J. Food Sci. Nutr., 60: 316-329.

194

Chakraverty, A., A.S. Mujumdar, G.S.V. Raghavan and H.S. Ramaswamy. 2003.

Handbook of Postharvest Technology. Marcel Dekker, New York.

Chao, C.T. and R.R. Krueger. 2007. The Date palm (Phoenix dactylifera L.): Overview of

biology, uses, and cultivation. Hort. Sci., 42: 1077-1082.

Chatha, G.A., A.H. Gillani and B. Ahmad. 1985. Effect of curing agents on the chemical

composition and keeping quality of date fruit. J. Agric. Res., 23: 71-77.

Chauhan, K.S. and C. Parmar. 1981. Degreening of Mosambi with ethrel. Third

International Symposium. Subtropical and Tropical Horticulture, Bangalore,

India, 8-14 Feb. Hort. Soc. India, P. 153-156.

Chauhan, K.S. and R.S. Rana. 1974. Effect of ethrel on degreening of Washington navel

orange. Indian J. Hort., 31: 154-156.

Cheng, T.S., J.D. Floros, R.L. Shewfelft and C.J. Chang. 1988. The effect of high

temperature-stress on ripening of tomatoes (Lycopersicon esculentum L.). J.

Plant Physiol., 132: 459-464.

Conrad, R.S. and F.J. Sundstrom. 1987. Calcium and ethephon effects on Tabasco pepper

leaf and fruit retention and fruit color development. J. Am. Soc. Hort. Sci., 112:

424-426.

Cooke, A.R. and D.I. Randall. 1968. 2-chloroethylphosphonic acids as ethylene releasing

agents for the induction of flowering in pineapples. Nature, 218: 974-975.

Coombe, B.G. 1973. The regulation of set and development of the grape berry. Acta Hort.

34: 261-274.

Costa, G. and G. Vizzotto. 2000. “Fruit thinning of peach trees,” Plant Growth Reg., 31:

113-119.

Couey, H.M. 1989. Heat treatment for control of postharvest diseases and insect pests of

fruits. Hort. Sci., 24: 198-202.

Crippen, D.D., and J.C. Morrison. 1986. The effects of sun exposure on the compositional

development of „Cabernet Sauvignon‟ berries. Amer. J. Enol. Viticul., 37: 235-

242.

Cua, A.U. and M.C. Lizada. 1990. Ethylene production in the 'Carabao' mango

(Mangifera indica L.) fruit during maturation and ripening. Acta Hort., 269:

169-179.

Curry, E.A. 1994. Pre-harvest applications of ethephon reduce superficial scald of „Fuji‟

and „Granny‟ apples in storage. J. Hort. Sci., 69: 1111-1116.

195

Davoodian, A. 1999. Effects of leaf area and growth regulators on fruit drop of

Mordasang date cultivar. Final Report of Research Design. Date Palm &

Tropical Fruits Research Institute of Iran, Ahwaz, Iran.

Dawson,W.H.W. 1982. Production and Preservation of date; Translated by R.

Sanadgol.Agricultural Promotion Organization Publication: Tehran, Iran, P.

326.

Delgado, R.., J.I. Gallegos, P. Martín and M.R. González. 2004. Influence of ABA and

ethephon treatments on fruit composition of „Trempranillo‟ grapevines. Acta

Hort., 640: 321-326.

Di-Marco, L., T. Caruso, F.P. Marra and A. Motisi, 1992. Research on flower thinning of

early-ripening peach and nectarine with urea. Fruit Var. J. 186-190.

Djerbi, M. 1996. Date palm Production (In French). Rome Italy; FAO, Agricultural

Services Bulletin.

Dokoozlian, N.K, D.A. Luvisi, P.L. Schrader and M.M. Moriyama. 1994. Influence of

trunk girdle timing and ethephon on the quality of Crimson Seedless table

grapes. In: Proc. Int. Symp. Table Grape Production. Am. Soc. Enol. Vitic.

(Eds.) Rantza, J.M. & Lewis, K.B., June, Anaheim, California, USA. P. 237-

240.

Dokoozlian, N.K. and W.M. Kliewer. 1996. Influence of light on grape berry growth and

composition varies during fruit development. J. Amer. Soc. Hort. Sci., 121:

869-874.

Doymaz, I. 2004. Convective air-drying characteristics of thin layer carrots. J. Food Eng.,

61: 359-364.

Doymaz, I. 2005. Drying characteristics and kinetics of okra. J. Food Eng., 69: 275-279.

Drake, S.R., D.C. Elfving and M.A. Drake. 2006. Effects of Aminoethoxyvinylglycine,

ethephon and 1-methylcyclopropene on apple fruit quality at harvest and after

storage. Hort. Technol., 16: 16-23.

Duke, J.A. 1992. Handbook of phytochemicals of GRAS herbs and other economic

plants. Boca Raton, FL, USA: CRC Press.

Ed Peter, K.V. 2009. Basics of Horticulture. New India Publishing Agency. Pitam Pura,

New Delhi India.

Edgerton, L.J. and G.D. Blanpied. 1970. Interaction of succinic acid 2, 2-dimethyl

hydrazide, 2chloroethylphosphonic acid and auxins on maturity, quality and

abscission of apples. J. Am. Soc. Hort. Sci., 95: 664-68.

196

El Arem, A., G. Flamini, E.B. Saafi, M. Issaoui, A. Ferchichi, M. Hammami and L.

Achour. 2011. Chemical and aroma volatile compositions of date palm

(Phoenix dactylifera L.) fruit at three edible maturation stages. Food Chem.,

127: 1744-1754.

El Hadrami, A., F. Daayf and I. El Hadrami. 2011. Date Palm Genetics and Breeding. pp.

479-502. In: Jain, S.M., J.M. Al-Khayri and D.V. Johnson (Eds.) Date Palm

Biotechnology, Springer, Netherlands.

El Hadrami, I. and A. El Hadrami. 2009. Breeding date palm. In: S. M. Jain and P. M.

Priyadarshan, (Eds.). pp. 191-216. Breeding Plantation Tree Crops. Springer,

New York.

El-Agamy, S.Z., T.K. El-Mahdy and O.A.A. Khalil. 2001. comparative study of the

performance of soft type date grown in arid environment. Second International

Conference on Date Palm, Al-Ain, U.A.E. March 25-27, P. 686-710.

El-Assar, A.M. 2005. Response of "Zaghloul" date yield and fruit characteristics to

various organic and inorganic fertilization types as well as fruit thinning

models in a rich carbonate soil. J. Agric. Sci., 30: 2795-2814.

El-Assi, N.M. 2004. Alleviating chilling injury and maintaining quality of tomato fruit by

hot water treatment. Emir. J. Agric. Sci., 16: 01-07.

El-Kereamy, A., C. Chervin, J. Raynal, M. Afifi and J.P. Roustan. 2000. Ethylene and

ethanol sprayed at véraison enhances the production of anthocyanins in,

„Cabernet Sauvignon‟ grapes. Abstr. 138 6th International Symposium on

Grapevine Physiology and Biotechnology. Heraklion, Greece 11-16 June.

Elleuch, M., S. Besbes, O. Roiseux, C. Blecker, C. Deroanne, N.E. Drira and H. Attia,

2008. Date flesh: Chemical composition and characteristics of dietary fibre.

Food Chem., 111: 676-682.

El-Shibli, S. and H. Korelainen. 2009. Biodiversity of date palm (Phoenix dactylifera L.)

in Sudan: Chemical, morphological and DNA polymorphism of selected

cultivars. Plant Genet. Resour., 7: 194-203.

Eltayeb, E.A., A.S. Al-Hasni and S.A. Farooq. 1999. Changes in soluble sugar content

during the development of fruits in some varieties of Omani date palm

(Phoenix dactylifera L.). Pak. J. Biol. Sci., 2: 255-258.

Ensminger, A.H. M.E. Ensminger, J.E. Konlande and J.R.K. Robson. 1995. The Concise

Encyclopedia of Foods and Nutrition; CRC Press LLC: Florida, USA, p.247.

197

Erskine, W., A.T. Moustafa, A.E. Osman, Z. Lashine, A. Nejatian, T. Badawi and S.M.

Ragy. 2004. Date Palmin the GCC countries of the Arabian Peninsula.

International Centre for Agricultural Research in the Dry Areas (ICARDA).

Fadel, M.A., L. Kurmestegy, M. Rashed and Z. Rashed. 2006. Fruit color properties of

different cultivars of dates (Phoenix dactylifera L.).Agricultural Engineering

International: the CIGR E journal, VIII (Manuscript FP 05 005).

Falade, K.O. and E.S. Abbo. 2007. Air-drying and rehydration characteristics of date

palm (Phoenix dactylifera L.) fruits. J. Food Eng., 79: 724-730.

Fallahi, M. 1996. Growth, Treatment, and Packaging of Date; Barsava Publication:

Tehran, Iran, P. 124.

Fallik, E., S. Grinberg, S. Alkalai, O. Oded Yekutieli, A. Wiseblum, R. Regev, H. Beres

and E Bar-Lev. 1999. A unique rapid hot water treatment to improve storage

quality of sweet pepper. Postharvest Biol. Technol., 15: 25-32.

FAOSTAT, 2011. Production Year Book. http:// Faostat.Fao.org/ site/ 339/deaflt.aspx.

Farag, K.M. 1989. Enhancing ethephon effectiveness by modifying cuticular transport or

stimulating ethylene production in cranberry fi-uit. Ph. D. Thesis. University of

Wisconsin-Madison. P. 216.

Farag, K.M., P. Jiwan and P. Palta. 1992. Ursolic acid, ascorbic acid or urea together with

ethephon accelerate anthocyanin production in cranberry fruit. J. Plant Growth

Regul., 20: 29-33.

Farahnaky, A. and H. Afshari-Jouybari. 2001. Physicochemical changes in Mazafati date

fruits incubated in hot acetic acid for accelerated ripening to prevent diseases

and decay. Sci. Hort., 127: 313-317.

Farahnaky, A., H. Askari, M. Bakhtiyari and M. Majzoobi. 2009. Accelerated ripening of

Kabkab dates using sodium chloride and acetic acid solutions. Iran Agric. Res.,

27: 99-111.

Fayadh, J.M. and S.S. Al-Showiman. 1990. Chemical composition of date palm (Phoenix

dactylifera L.). J. Chem. Soc. Pak., 12: 84-103.

Frenkel, C. and T.G. Hartman. 2012. Decrease in fruit moisture content heralds and might

launch the onset of ripening processes. J. Food Sci., 77: 365-376.

Fuch, Y. and A. Cohen. 1969. De-greening of citrus fruit with ethrel. J. Am. Soc. Hort.

Sci., 94: 617-618.

Gala, M.S.; A.A.A. El-Aziz and A.R. El-Tawil. 2001. Using ethrel for banana ripening.

Egyptian J. Agric. Res., 79: 271-295.

198

Gamage, T.V. and M.S. Rehman.. 1999. Post-harvest handling of foods of plant origin.

In: Rehman, M.S. (Ed.) Handbook of Food Preservation. Marcel Dekker Inc.,

New York. P. 11-46.

Garcia-Jimenez, J., J. Busto, A. Vicent, and J. Armengol. 2004. Control of Dematophora

necatrix on Cyperus esculentus tubers by hot-water treatment. Crop Protect.,

23: 619-623.

Gasim, A.A.A. 1994. Changes in sugar quality and mineral elements during fruit

development in five date palm cultivars in Al-Madinah Al-Munawwarah.

JKAU: Sci., 6: 29-36.

Gautier, H., V. Diakou-Verdin, C. Benard, M. Reich, M. Buret, F. Bourgaud, J.L.

Poessel, C. Caris-Veyrat and M. Genard. 2008. How does tomato quality

(sugar, acid, and nutritional quality) vary with ripening stage, temperature, and

irradiance? J. Agric. Food Chem., 56: 1241-1250.

Godara, R.K., N.R. Godara and N.S. Nehra. 1990. Effect of level of thinning on ripening

of date palm fruit (Phoenix dactylifera L.) cv. Shamran. Res. Dev. Rep., 7: 21-

25.

Goffinet, M.C., T.L. Robinson and A.N. Lakso. 1995. A comparison of „Empire‟ apple

fruit size and anatomy in un-thinned and hand thinned trees. J. Hort. Sci., 70:

375-387.

Goldschmidt, E.E., M. Huberman, and R. Goren, 1993. Probing the roles of endogenous

ethylene in the degreening of citrus fruit with ethylene antagonists. J. Plant

Growth Regul., 12: 325-329.

GOP (Government of Pakistan), 2011. Fruit, Vegetable and Condiments. Statistics of

Pakistan. Ministry of Food, Agriculture and Livestock (Economic Wing),

Islamabad.

Gray, J., S. Pictor, J. Shabbeer, W. Schuch and D. Grierson 1992. Molecular biology of

fruit ripening and its manipulation with antisense genes. Plant Mol. Biol., 19:

69-87.

Grierson, D., G.A. Tucker and N.G. Robertson. 1981. The molecular biology of ripening.

In: Friend, J., and Rhodes, M.J.C., (Eds.). Recent Advances in the

Biochemistry of Fruits and Vegetables. Academic Press, London. 149-160 pp.

Guine, R.P.F. and J.A.A.M. Castro. 2002. Pear drying process analysis: Drying rates and

evaluation of water and sugar concentrations in space. Dry. Tech., 20: 1515-

1526.

199

Hammam, M.S., A. Sabour and E. Sanaa. 2002. Effect of some fruit thinning treatments

on yield and fruit quality of Zaghloul date palm. J. Agric. Sci., 10: 261-271.

Hammett, L.K. 1976. Ethephon influence on storage quality of „Starkrimson Delicious‟

and „Golden Delicious‟ apples. Hort. Sci., 11: 57-59.

Hamshiri, M.H. and M. Rahemi. 1999. Effect of ethphon, sodium chloride and acetic acid

on quality of Mazafati date fruits. Iranian J. of Agri. Sci. 29 (4): 777-785.

Han, D.H., S.M. Lee, C.H. Lee and S.B. Kim. 1996. Effects of ABA and ethephon

treatments on coloration and fruit quality in Kyoho grape. J. Kor. Soc. Hort.

Sci., 37: 416-420.

Haq, Z. 1990. Effect of NaCl and acetic acid on physio-chemical character and storage of

date fruit (Phoenix dactylifera L.) cv. Dhakki under the normal conditions.

M.Sc. Thesis. Uni. Agri., Faisalabad.

Harman, J.E. and K.J. Patterson. 1984. Kiwi fruit, tamarillos and feijoas maturity and

storage effect on keeping and eating quality. Agric. Link.

Hartmann, C. 1992. Biochemical changes in harvested cherries. Postharvest Biol.

Technol., 1: 231-240.

Hasegawa, S. And D.C. Smolensky. 1971. Cellulase in dates and its role in fruit

softening. J. Food Sci., 36: 966-967.

Hasegawa, S. and V.P. Maier. 1980. Polygalacturonase content of dates and its relation to

maturity and softness. J. Food Sci., 34: 527-529.

Hashempoor, M. 1999. Date Treasure; Agricultural Education Publication: Tehran, Iran,

P. 668.

Hashinaga, F. and S. Itoo. 1985. Effect of ethephon on the maturity of Meiwa Kumquat

fruit. Bulletin Faculty of Agriculture Kagoshime University. 35: 43-47.

Hole, C.C. and P.A. Scott. 1981. The effect of fruit shading on yield in Pisum sativum L.

Ann. Bot., 48: 827-835.

Hong, M.N., B.C. Lee, S. Mendonca, M.V.E. Grossmann and R. Verhe. 1999. Effect of

infiltrated calcium on ripening of tomato fruits. LWT. J. Food Sci., 33: 2-8.

Hong, Y.J., F.A. Tomas-Barberan, A.A. Kader and A.E. Mitchell. 2006. The flavonoids

glycosides and procyanidin composition of Deglet Noor dates (Phoenix

dactylifera L.). J. Agric. Food Chem., 54: 2405-2411.

Hortwitz, W. 1960. Official and tentative method of analysis. Association of Official

Agriculture Chemists, Washington, D.C., 9: 314-320.

200

Hoyer, L. 1996. Critical ethylene exposure for Capsicum annuum “janne” is dependent on

an interaction between concentration, duration and developmental stage. J.

Hort. Sci., 71: 621-628.

Hui, Y.H. 2006. Fruit and Fruit Processing; Blackwell Publishing: Ames, Iowa. P. 391-

411.

Hulme, A.C. 1970. The biochemistry of fruits and their products, Vol. 1, London and

New York: Academic Press.

Hussein, M.A., Z. Samir, EI-Agamy, A.K. Amin and S. Gala. 1993. Physiological studies

for extending harvesting season of Samany dates under Assiut conditions. B.

Effect of ethephon and fruit thinning. Third Symposium on date palm in Saudia

Arabia. P. 106.

Ibrahim, A.M. and M.N.H. Khalif. 1998. The date palm: Its Cultivation, Care and

Production in the Arab World. Almaarif Public Company, Alexandria, Egypt.

Iizadi, M., M.P. Shirazi, A.D. Avoodian and B. Damankeshan, 2010. Effect of bunch

thinning methods on date bunch fading disorder at pollination and kimri stages.

Fourth International Date Palm Conference, Abu Dhabi, U.A.E. 15-17 March.

P. 57.

Inaba, M. and K. Chachin. 1988. Influence of and recovery from high-temperature stress

on harvested mature green tomatoes. Hort. Sci., 23: 190-192.

Ishurd, O. and J.F. Kennedy. 2005. The anti-cancer activity of polysaccharide prepared

from Libyan dates (Phoenix dactylifera L). Carbohydr. Polym., 59: 531-535.

Itamura, H., T. Kitamura, Taira, H. Harada, N. Ito, Y. Takahashi and T. Fujushima. 1991.

Relationship between fruit softening, ethylene production and respiration in

Japanese persimmon “Hiratanenashi”. J. Japanese Soc. Hort. Sci., 60: 695-701.

Jabbar, A., A.U. Malik, M. Saeed, O.H. Malik, M. Amin, A.S. Khan, I.A. Rajwana, B.A.

Saleem, R. Hameed and M.S. Mazhar. 2011. Performance of hot water

phytosanitary treated mangoes for intended export from Pakistan to Iran and

China. Int. J. Agric. Biol., 13: 645-651.

Jacobi, K., E. MacRae and S. Hetherington. 2001. Postharvest heat disinfestations

treatments of mango fruit (Review). Sci. Hort. Cult., 89: 171-193.

Jacobi, K.K., L.S. Wong and J.E. Giles. 1995. Effect of fruit maturity on quality and

physiology of high humidity hot air treated „Kensington‟ mango (Mangifera

indica Linn.). Post-harvest Biol. Technol., 5: 149-59.

201

Jamil, M.S., R. Nadeem, M.A. Hanif, M.A. Ali and K. Akhtar. 2010. Proximate

composition and mineral profile of eight different unstudied date (Phoenix

dactylifera L.) varieties from Pakistan. Afr. J. Biotechnol., 9: 3252-3259.

Johnson, T.L. and C.W. Nagel. 1976. Composition of Central Washington grapes during

maturation. Am. J. Enol. Viticul., 27: 15-20.

Jones, K. M. 1979. The use of ethephon in advancing red colour in the apple cultivar

'Tydeman Early'. Aust. J. Exp. Agri. Animal Husb., 19: 251-256.

Kader, A.A. 1986. Effects of postharvest handling procedures on tomato quality. Acta

Hort., 190: 209-221.

Kader, A.A. and A. Hussein. 2009. Harvesting and post-harvest handling of dates.

ICARDA, Aleppo, Syria. P. 15.

Kahn, B.A., J.E. Motes and N.O. Maness. 1997. Use of ethephon as a controlled

abscission agent on paprika pepper. Hort. Sci., 32: 251-255.

Kalra, S.K., J.S. Jawanda and S.K. Munshi. 1977. Studies on softening of Doka dates by

sodium chloride and acetic acid. Ind. J. Hort., 34: 220-224.

Kamal, H.M. 1995. Effect of some growth regulators on the physical and chemical

properties of date fruits. AGRIS Bull., 46: 215-228.

Kappel, F. and G.H. Neilsen. 1994. Relationship between light microclimate, fruit

growth, fruit quality, specific leaf weight and N and P content of spur leaves of

„Bartlett‟ and „Anjou‟ pear. HortScience, 59: 187-196.

Kato, K. 1990. Astringency removal and ripening in persimmons treated with ethanol and

ethylene. HortScience, 25: 205-207.

Kenoyer, J. Mark and K. Heuston. 2005. The Ancient South Asian World. Oxford

University Press. 176 pages. ISBN 0-19-517422-4.

Ketsa, S., S. Childtragool, J.D. Klein and S. Lurie. 1998. Ethylene synthesis in mango

fruit following heat treatment. Postharvest Biol. Technol., 15: 65-72.

Ketsa, S., S. Childtragool, J.D. Klein and S. Lurie. 1999. Ethylene synthesis in mango

fruit following heat treatment. Postharvest Biol. Technol., 15: 65-72.

Khademi, R. 1998. Effects of different methods of fruit thinning on fruit ripening,

quantity and quality of Kabkaab dates. Final Report of Research Design.

Agricultural Research Center of Boushehr, Boushehr, Iran.

Khalifa, A.S., A.I. El-Kady, K.M. Abdalla and A.M. El-Hamdy. 1987. Influence of

thinning patterns and leaf/bunch ratio on “Zaghloul” dates. Ann. Agric. Sci.,

32: 637-647.

202

Khalifa, A.S., M. Abdel-Azeem, EI-Hammady, M. Mostafa, EI-Hammady and A. Yussuf.

1975. Ripening of date fruits as affected by ethephon. Egypt. J. Hort., 2: 83-

102.

Khare, C.P. 2007. Indian medicinal plants: An illustrated dictionary. Springer Reference.

Khatchadourian, H.A., W.N. Sawaya, J.K. Khalil, W.J. Safi and A.A. Mashadi. 1982.

Utilization of dates, (Phoenix dactylifera L.), grown in the Kingdom of Saudi

Arabia, in various date products. First International Symposium on date palm.

King Faisal University, Saudi Arabia, March, 23-25.

Kim, D.O., S.W. Jeong and C.Y. Lee. 2003. Antioxidant capacity of phenolic

phytochemicals from various cultivars of plums. Food Chem., 81: 321-326.

Kim, H.C. 2010. Effect of Ethephon on Fruit Enlargement and Coloring of 'Fuyu'

Persimmon. Korean J. Hort. Sci. Technol., 28: 757-761.

Knavel, D.E. and T.R. Kemp. 1973. Ethephon and CPTA on color development in bell

pepper fruits. Hort. Sci., 8: 403-404.

Kudachikar, V.B., S.G. Kulkarni, M.N.K. Prakash, M.S. Vasantha, B.A. Prasad and

K.V.R Ramana, 2001. Physico-chemical changes during maturity of mango

(Mangifera indica L.) Variety "Neelum" J. Food Sci. Technol., 38: 540-542.

Kulkarni, S.G., V.B. Kudachikar, M.S. Vasantha, M.N.K. Prakash, B.A. Prasad and

K.V.R. Ramana. 2004. Studies on effect of ethrel dip treatment on the ripening

behaviour of mango (Mangifera indica, L.) variety „Neelum‟. J. Food Sci.

Technol., 41: 216-220.

Lambiote, B. 1982. Some aspects of the role of dates in human nutrition. First

International Symposium on Date palm. King Faisal University, Saudi Arabia,

March, 23-25.

Larrigaudiere, C., E. Pinto and M. Vendrell, 1996. Differential effects of ethephon and

seniphos on color development of „Starking Delicious‟ apple. J. Am. Soc. Hort.

Sci., 121: 746-750.

Lemaux, G. 1999. Plant Growth Regulator and Biotechnology: Western Plant Growth

Regulator Society Presentation Anaheim CA.

Lewicki, P.P. 1998. Some remarks on rehydration of dried foods. J. Food Eng., 36: 81-87.

Li, Z., S. Sugaya, H. Gemma and S. Iwahori. 2002. Flavonoid biosynthesis and

accumulation and related enzyme activities in the skin of „Fuji‟ and „Orin‟

apples during their development. J. Jpn. Soc. Hort. Sci., 71: 317-321.

203

Lieberman, A. 1979. Biosynthesis and action of ethylene. Ann. Rev. Plant Physiol., 30:

533-591.

Lin, Z.F., S.L. Zhong and D. Grierson, 2009. Recent advances in ethylene research. J.

Exp. Bot., 60: 3311-3336.

Lippert, F. and M.M. Blanke. 2004. Effect of mechanical harvest and timing of 1-MCP

application on respiration and fruit quality of European plums (Pyrus

domestica L.). Postharvest Biol. Technol., 34: 305-311.

Lipton, W.J. 1990. Postharvest biology of fresh asparagus. Hort. Rev., 12: 69-155.

Liu, H., Y. Cao, W. Huang, Y. Guo and Y. Kang. 2013. Effect of ethylene on total

phenolics, antioxidant activity, and the activity of metabolic enzymes in mung

bean sprouts. Eur. Food Res. Technol., 237: 755-764.

Lizada, C. 1993. Mango. In: Seymour, G.B., Taylor, J.E., and Tucker, G.A. (Eds.)

Biochemistry of Fruit Ripening. Chapman and Hall, London, 255-271.

Lombard, P.J., J.A. Viljoen, E.E. Wolf and F.J. Calitz. 2004. The effect of ethephon on

berry colour of „Flame Seedless‟ and „Bonheur‟ table grapes. S. Afr. J. Enol.

Viticul., 25: 1-12.

Looney, N.E. 1998. Plant bio-regulators in fruit production: an overview and outlook. J

Korean Soc. Hort. Sci., 39: 125-128.

Lopez, S., J.V. Maroto, A. San-Bautista, B. Pascual and J. Alagarda. 2000. Qualitative

changes in pepino fruits following pre-harvest applications of ethephon. Sci.

Hort., 83: 157-164.

Lunde, P. 1978. A History of Dates. Saudi Aramco World, 29: 176-179.

Lurie, S. and A. Nussinovich. 1996. Compression characteristics firmness, and texture

perception of heat treated and unheated apples. Int. J. Food Sci. Technol., 31:

1-5.

Lurie, S. and J.D. Klein. 1990. Heat treatment on ripening apples: Differential effect on

physiology and biochemistry. Physiol. Plant, 78: 181-186.

Lurie, S.1998. Postharvest heat treatment review. Postharvest Biol. Technol. 14: 257-269.

Maillard, M.N. and C. Berset. 1995. Evolution of antioxidant activity during kilning: role

of insoluble bound phenolic acids of barley and malt. J. Agric. Food Chem., 43:

1789-1793.

Malik, A.U., Z. Singh and S.S. Dhaliwal. 2003. Exogenous application of putrescence

affects mango fruits quality and shelf life. Acta Hort., 628: 121-27.

204

Malundo, T.M.M., R.L. Shewfelt, G.O. Ware and E.A. Baldwin. 2001. Sugars and acids

influence flavor properties of mango (Mangifera indica L.). J. Amer. Soc. Hort.

Sci., 126: 115-21.

Mann, S.S. 1985. Effect of ethylene and acetylene on the ripening of mango fruits. Acta

Hort., 158: 409-412.

Marin-Rodriguez, M.C., J. Orchard, and G.B. Seymour. 2002. Pectate lyases, cell wall

degradation and fruit softening. J. Exp. Bot., 53: 2115-2119.

Marlett, J.A., M.I. McBurney and J.L. Slavin. 2002. Position of the American Dietetic

Association: Health implications of dietary fibre. J. Am. Diet Assoc., 102: 993-

1000.

Marrero, A. and R.E. Paull. 1998. Physiological effects of hot water treatments on banana

fruits. Acta Hort., 464: 518-518.

Marzouk, H.M., A.M. El-Salhy, H.A. Abdel-Galil and A.E. Mahmoud. 2007. Yield and

fruit quality of some date palm cultivars in response to some flower thinning

rates. Fourth Symposium on Date palm in Saudi Arabia. King Faisal Univ., Al-

Hassa, 5-7 May, P. 110.

Maximos, S.E., A.B.A. Aziz, I. M. Desouky and N.S. Antoun, 1980. Effect of GA3 and

ethephon on the yield and quality of Seewy date fruits. Moshtohor. Ann. Agri.

Sci., 12: 251-262.

Mazumdar, B.C. and D.N.V. Bhatt. 1976. Effects of pre-harvest application of GA and

Ethrel on sweet orange. Prog. Hort., 8: 89-91.

Mcdonald, R.E., T.G. Mccollum and E.A. Baldwin. 1999. Temperature of water

treatments influences tomato fruit quality following low temperature storage.

Postharvest Biol. Technol., 16: 147-155.

Mc-Glasson, W.B. 1985. Ehylene and fruit ripening. HortScience, 20: 51-54.

Messaïtfa, A. 2008. Fluoride contents in ground waters and the main consumed foods

(dates and tea) in Southern Algeria region. Environ. Geol., 55: 377-383.

Mignani, I., L.C. Greve, R. H.U. Ben-Ari and C.L. Stotz. 1995. The effect of GA3 and

divalent cations on aspects of pectin metabolism and tissue softening in

ripening tomato pericarp. Physiol. Plant, 93: 108-115.

Mikki, M.S. 1998. Present status and future prospects of dates and date industry in Saudi

Arabia. In: M. Al-Afifi, M and A. Al-Badawi (Eds.), Proceedings of the First

International Conference on Date Palm, Al Ain, United Arab Emirates. 8-10

March, P. 469-507.

205

Miller, C.J., E.V. Dunn and I.B. Hashim. 2003. The glycaemic index of dates and

date/yoghurt mixed meals. Are dates “the candy that grows on trees”? Eur. J.

Clin. Nutr., 57: 427-430.

Mirza, A.K. and S. Meraj-ud-Din. 1988. Effect of chemical treatment on the composition

of date cultivars. Sarhad J. Agric., 4: 435-442.

Mohamed, A.E. 2000. Trace element levels in some kinds of dates. Food Chem., 70: 9-

12.

Morgan, D.C., C.J. Stanley, R. Volz and I.J. Warrington. 1984. Summer pruning of

„Gala‟ apple: the relationships between pruning time, radiation penetration, and

fruit quality. J. Am. Soc. Hort. Sci., 109: 637-642.

Morrison, J.C. and A.C. Noble. 1990. The effects of leaf and cluster shading on the

composition of Cabernet Sauvignon grapes and on fruit and wine sensory

properties. Amer. J. Enol. Viticul., 41: 193-200.

Morton, J.F. 1987. Fruits of Warm Climates; Florida Flair Books: Miami, USA, P. 9.

Mostafa, R.A.A. and M.M. El. Akkad. 2011. Effect of Fruit Thinning Rate on Yield and

Fruit Quality of Zaghloul and Haiany Date Palms. Aust. J. Basic App. Sci., 5:

3233-3239.

Mougheith, M.G. and G.I. El-Banna. 1974. Effect of ethrel spray on maturation of Sultani

fig. Ann. Agric. Sci., 2: 100-113.

Mougheith, M.G. and L.A. Hassaballa. 1979. Effect of pre-harvest spray of some growth

regulating substances on yield and fruit characteristics of Hayany date cultivar.

Research Bulletin, Faculty of Agriculture, Ain-Shams University, P. 21.

Moustafa, A.A. 1993. Effect of fruit thinning on yield and fruit quality of Seewy date

palms under El-Fayoum Governorate conditions. The Third Symposium on the

date palm in Saudi Arabia. King Faisal Univ, Al-Hassa. Vol. 1. January 17-20.

Mrak, E.M., H.J. Phaff, R.L. Perry, G.L. Marsh and C.D. Fisher. 1946. Fruit dehydration.

California Univ. Agricultural Experiment Station Bulletin 698. Berkeley, Calif.

Murphey, A.S. and D.R. Dilley. 1988. Anthocyanin biosynthesis and maturity of

„McIntosh‟ apples as influenced by ethylene releasing compounds. J. Am. Soc.

Hort. Sci., 113: 718-723.

Musa, S.K. 2001. Early ripening of dates using ethrel, p. 36-46. In: M. Al-Afifi and A.

Al-Badawi (eds.). New Dimensions and Challenges for Sustainable Date Palm

Production: From Farm to Fork. Second International Date Palm Conference,

Al-Ain, U.A.E., 25-27 March

206

Mustafa, A.B., D.B. Harper and D.E. Johnston. 2006. Biochemical changes during

ripening of some Sudanese date varieties. J. Sci. Food Agri., 37: 43-53.

Myers, S.C., A. King and A.T. Savelle, 1993. Bloom thinning of „Wimblo‟ peach and

„Fantasia‟ nectarine with monocarbamide dihydrogensulfate. HortScience, 28:

616-617.

Myhara, R.M., J. Karkalas and M.S. Taylor. 2000. The composition of maturing Omani

dates. J. Sci. Food Agric., 79: 1345-1350.

Naik, D.M., V.G. Mulekar, C.G. Chandel and B.M. Kapse. 1993. Effect of pre-packaging

on physico-chemical changes in tomato (Lycopersicon esculentum Mill.) during

storage. Indian Food Packer.

Najeh, D., T. Taher and B. Kacem.1999. Tunisian Deglet Noor dates ripening, processing

and storage. Ciheam-Iamc., 179-184.

Nikolaou, N., E. Zioziou, D. Stavrakas and A. Patakas. 2003. Effects of ethephon,

methanol, ethanol and girdling treatments on berry maturity and colour

development in Cardinal table grapes. Austr. J. Grape Wine Res., 9: 12-14.

Nittaya, U., T.K. Matsumoto, M.M. Wall and K. Seraypheap. 2011. Changes in

antioxidants and fruit quality in hot water-treated „Hom Thong‟ banana fruit

during storage. Sci. Hort., 130: 801-807.

Nixon, R.W. 1951. The date palm: "Tree of Life"in the subtropical deserts. Econ. Bot., 5:

274-301.

Nixon, R.W. and J.B. Carpenter. 1978. Growing dates in the United States. United States

Department of Agriculture Bulletin no. 207, U.S. Department of Agriculture,

Washington, DC.

Nodiya, M.G. and V.E. Mikaberidze. 1991. Effect of ethylene-producing agents and

gibberellic acid on ripening and quality of Unshiu mandarins. Subtropicheskie-

K;ul‟tury, 4: 85-89.

Olaiya, C.O. and O. Osonubi. 2009. Effects of pre-sowing seed treatments on tomato

Lycopersicon esculentum (L.) Mill) seedling emergence. Int. J. Eng. Technol.,

1: 321-323.

Olorunda, A.O., O.C. Aworth and C.N. Onuoha. 1990. Upgrading quality of dried

tomato: Effects of drying methods, conditions and pre-drying treatments. J. Sci.

Food Agric., 52: 447-54.

Padmini, S. and T.N. Prabha. 1997. Biochemical changes during acetylene-induced

ripening in mangoes (var. Alphonso). Tropical Agric., 74: 265-271.

207

Park, S.J., D.S. Chung, S.S. Hong and Y.B. Kim. 1998. Application of a simple ethylene

generating kit for removal of astringency and softening of persimmon

(Diospyros kaki, Thumb). J. Korean Soc. Hort. Sci., 39: 727-731.

Prasanna, V., T.N. Prabha, and R.N. Tharanathan. 2007. Fruit Ripening Phenomena–An

Overview. Critical Rev. Food Sci. Nutr., 47: 1-19.

Profio, F.D., G. Andrew, Reynolds1 and A. Kasimos. 2012. Canopy Management and

Enzyme Impacts on Merlot, Cabernet franc, and Cabernet Sauvignon. I. Yield

and Berry Composition. Amer. J. Enol. Viticul., 63: 325-332.

Prohens, J., J.J. Ruiz and F. Nuez. 1999. Yield, earliness and fruit quality of pepino

clones and their hybrids in the autumn-winter cycle. J. Sci. Food Agric., 79:

341-346.

Pudmini, S. and T.N. Prabha. 1997. Biochemical changes during acetylene-induced

ripening in mango (var. Alphorns). Trop Agric. (Trinidad), 74: 265-271.

Puech, A.A., C.A. Rebeiz and J.C. Crane. 1976. Pigment changes associated with

application of ethephon (2-Chloroethyl) phosphonic Acid) to fig (Ficus carica

L.) fruits. Plant Physiol., 57: 504-509.

Purandhare, N.D., D.M. Khedkar and M.B. Sontakke. 1992. Physico-chemical changes

during degreening in sweet orange. South Indian Hort., 40: 128-132.

Puri, A., R. Sahai, K.L. Singh, R.P. Saxena, J.S. Tandon and K.C. Saxena. 2000.

Immunostimulant activity of dry fruits and plant materials used in Indian

traditional medical system for mothers after childbirth and invalids. J. Ethno-

pharmacology, 71: 89-92.

Rajwana, I.U., A.U. Malik, A.S. Khan, B.A. Saleem and S. Ahmad. 2010. A new mango

hybrid shows better shelf life and fruit quality. MSc. Thesis Uni. College of

Agric, Bahauddin Zakariya Uni, Multan, Pakistan.

Ramana, K.V.R., S. Saroja, G.R. Setty, A.M. Nanjundaswamy and N.V.N. Moorthy.

1973. Preliminary studies to improve the quality of Coorg monsoon mandarin.

Indian Food Packer, 27: 5-9.

Ratti, C. 2001. Hot air and freeze-drying of high-value foods: A review. J. Food Eng., 49:

311-319.

Riad, M. 2006. The date palm sector in Egypt. CIHEAM-Options Mediterraneanes, 45-

53.

Rohani, A. 1988. Date palm; Tehran University Publication Center: Tehran, Iran, p. 292.

208

Rohani, A., W.A. Nazni, L.V. Ngo, J. Ibrahim and H.L. Lee. 1997. Adulticidal properties

of the essential extracts of some Malaysian plants on vector mosquitoes.

Tropical Biomedicine, 14: 5-9.

Ross, E.B. 1993. Controlling Growth of Bearing Apple Trees with Ethephon. Hort. Sci.,

28: 1103-1105.

Rouhani, I. and A. Bassiri. 1977. Effect of ethephon on ripening and physiology of date

fruits at different stages of maturity. J. Hort. Sci., 52: 289-197.

Ruck, J.A. 1961. Chemical method for analysis of fruit and vegetable products. Res. Sta.

Summerland., Res. Branch, Canada. Dept. of Agri. No. 1154.

Sahari, M.A., M. Barzegar and R. Radfar. 2007. Effect of varieties on the composition of

dates (Phoenix dactylifera L.). Food Sci. Technol. Int., 13: 269-275.

Saheeh Bukhaari. 2001. “Hadith”. Kademi Kitab Khana, Karachi, Publisher (in Arabic).

Vol. 2. P. 181.

Saleem, S.A., A.K. Baloch and M.K. Balocch. 2005. Accelerated ripening of Dhakki

dates by artificial means: ripening by acetic acid and sodium chloride. J. Food

Eng., 70: 61-66.

Saleem, S.A., M.K. Baloch, K. Ahmad and A.K. Baloch. 2002. Effect of ripening by

microwave radiation on quality of Dhakki dates. J. Biol. Sci., 2: 238-242.

Samarawira, I. 1983. Date Palm, Potential Source for Refined Sugar. Econ. Bot., 37: 181-

186.

Samavi, H. 1998. Determination of the best thinning method of Mordasang date cultivar.

Final Report of Research Design. Agricultural Research Center of Hormozgan,

Bandar Abbas, Iran.

Sandhu, S.S., S.S. Thind and J.S. Bal. 1989. Effect of pre-harvest spray of ethephon on

size, quality and ripening of ber (Ziziphus mauritiana Lamk.) Cv. Umran.

Indian J. Hort., 46: 23-27.

Sanghvi, K.U. and Patil, A.V. 1983. Effect of Ethrel on nucellar Mosambi fruits (C.

sinensis Osbeck). Proc. Int. Citrus Symposium, 17-22 December, Bangalore,

Hort. Soc. India, P. 322-325.

Sarig,Y. 1989. An integrated mechanical system for date orchard operation, ASAE P. 89-

1069.

Sauer, J. 1993. Phoenix-Date palms. In historical geography of crop plants. Boca Raton,

FL: CRC Press. P. 182-186.

209

Sawaya, W.N. J.K. Khalil, W.N. Safi and A. Al-Shalhat. 1983. Physical and chemical

characterization of the Saudi date cultivars at various stages of development.

Can. Ins. Food Sci. Technol. J., 16: 87-91.

Sayyahpoor, H. 2002. Determination of the best thinning method of Sayer date cultivar.

Final Report of Research Design. Date Palm & Tropical Fruits Research

Institute of Iran, Ahwaz, Iran.

SBI [Sindh Board of Investment]. 2010. Date‟s Hydration and De-hydration Plant. Sindh,

Pakistan.

Selvam, A.B.D. 2008. Inventory of vegetable crude drug samples housed in botanical

survey of India, Howrah. Pharmacognosy Rev., 2: 61-94.

Sergent, E., B. Schaffer, S.P. Lara and E. Willis. 1993. Effect of ethephon on mango

(Mangifera indica L.) fruit quality. Acta Hort., 341: 510-517.

Shahidi, F. and M. Naczk. 2004. Phenolics in food and nutraceuticals. Boca Raton, FL:

CRC Press.

Shahnawaz, M., S.A. Sheikh, A.A. Panwar, S.G. Khaskheli and F.A. Awan. 2012. Effect

of hot water treatment on the chemical, sensorial properties and ripening

quality of Chaunsa Mango (Mangifera indica L.). J. Basic App. Sci., 8: 328-

333.

Shamshiri, M.H. and M. Rahemi. 1999. Effect of ethephon, sodium chloride and acetic

acid on quality of Muzafati date fruits. Iranian J. Agri. Sci., 29: 777-785.

Shiota, M., M.C. Moore, P. Galassetti, M. Monohan, D.W. Neal, G.I. Shulman and A.D.

Cherrington. 2002. Inclusion of low amounts of fructose with an intraduodenal

glucose load markedly reduces postprandial hyperglycemia and

hyperinsulinemia in the conscious dog. Diabetes, 51: 469-478.

Sims, W.L., H.B. Collins and B.L. Gledhill. 1970. Ethrel effects on fruit ripening of

peppers. Calif. Agric., 24: 4-5.

Singh, H.P., K.C. Srivastava, K. Ganapathy, D.P. Muthappa and G.S. Randhawa. 1978.

Effect of ethephon (2-chloroethyl phosphonic acid) on post-harvest degreening

of mandarin and sweet orange. Vatika, 1: 56-63.

Singh, Z., J. Janes, Z. Singh, R. Ben-Arie and S. Philosoph-Hadas. 2001. Effects of

postharvest application of ethephon on fruit ripening, quality and shelf life of

mango under modified atmosphere packaging. Acta Hort., 553: 599-602.

Sisler, E. and S. Fa-Yang. 1984. Ehylene, the gaseous plant hormone. Biol. Sci. 34: 234-

238.

210

Smith, L.G. 1991. Effects of ethephon on ripening and quality of freshmarket pineapples.

Aus. J. Exp. Agric., 31: 123-127.

Smithyman, R. P., G.S. Howell and D.P. Miller. 1998. The use of competition for

carbohydrates among vegetative and reproductive sinks to reduce fruit set and

botrytis bunch rot in seyval blanc grapevines.Am. J. Enol. Viticul., 49: 163-

170.

Soliman, S.S. and M.M. Harhash, 2012. Effects of strands thinning on yield and fruit

quality of Succary date palm. African J. Biotechnol., 11: 2672-2676.

Soliman, S.S., R.S. Al-Obeed and M.M. Harhash. 2011. Effects of bunch thinning on

yield and fruit quality of Khalas date Palm cultivar. World Appl. Sci. J., 12:

1187-1191.

Soni, S.L. and S.L. Ameta. 1983. Effect of pre-harvest application of ethrel on coloration

and physico-chemical composition of grapefruit. Proc. Int. Citrus Symposium

Bangalore, Hort. Soc. India, P. 309-315.

Sonkar, R.K. and M.S. Ladaniya. 1999. Effect of pre-harvest spray of ethephon, Calcium

acetate and Carbendazim on rind color, Abscission and shelf life of Nagpur

Mandrin (Citrus reticulate). Indian J. Agric. Sci., 69: 130-135.

Srinivasa, P.C., R. Baskaran, M.N. Ramesh, K.V.H. Prashanth and R.N. Haranathan,

2002. Storage studies of mango packed using biodegradable chitosan film. Eur.

Food Res. Tech., 215: 504-508.

Stanly, D.W., M.C. Bourne, A.P. Stone and W.V. Wismer. 1995. Low temperature

blanching effects on chemistry, firmness and structure of canned green beans

and carrots. J. Food Sci., 60: 327-333.

Steel, R. G. D., J. H. Torrie and D. A. Dickey. 1997. Principles and Procedures of

Statistics. New York: McGraw-Hill.

Steenkamp, J., K.L. Blommaert and J.H. Jooste. 1977. Invloed van ethephon op die

rypwording van druiwe (Vitis vinifera L. „Barlinka‟). Agroplante, 9: 51-54.

Stewart, I. 1977. Citrus color-A review. Proc. Int. Citrus Congress, Florida, Vol. 1, P.

308-311.

Suresh, N. and S. Zora. 2003. Pre storage ethrel dip reduces chilling injury, enhances

respiration rate, ethylene production and improves fruit quality of „Kensington‟

mango. J. Food Agric. Environ., 1: 93-97.

211

Szyjewicz, E., N. Rosner and M.W. Kliewer. 1984. Ethephon (2-chloroethylphosphonic

acid, Ethrel, CEPA) in viticulture: A review. Amer. J. Enol. Viticul., 35: 117-

123.

Tafti, A.G. and M.H. Fooladi. 2004. A study on the physico-chemical properties of

Iranian Shamsaei date at different stages of maturity. World J. Dairy Food Sci.,

1: 28-32.

Tahraoui, A., J. El-Hilaly, Z.H. Israili and B. Lyoussi. 2007. Ethnopharmacological

survey of plants used in the traditional treatment of hypertension and diabetes

in southeastern Morocco (Errachidia province). J. Ethno-pharmacology, 110:

105-117.

Taira, S., T. Satoh and S. Watanabe. 1991. Removal of the astringency taste from

persimmons and softening following treatment. Agric. Hort., 66: 1401-1404.

Tamura, F., K. Tanabe, A. Hai and M. Hasegawa. 1999. Characteristics of acetaldehyde

accumulation and removal of astringency with ethanol and carbon dioxide

treatments in “Saijo” persimmon fruit. J. Japanese Soc. Hort. Sci., 68: 1178-

1183.

Tapas, A.R., A.M. Sakarkar and R.B. Kakde. 2008. Flavonoids as nutraceuticals: A

review. Tropical J. Pharmaceutical Res., 7: 1089-1099.

Tavakkoli, A., E. Tafazoli and M. Rahemi. 1994. Comparison of the effects of hand

thinning and chemical thinning on fruit quantity and quality and alternate

bearing of Shahani date cultivar. Proc. the 1st Date Seminar. Boushehr. Iran

24-27 January. P. 107-118.

Theologis, A. 1993. One rotten apple spoils the whole bushel: the role of ethylene in fruit

ripening. Cell, 70: 181-184.

Thomas, P. and M.S. Oke. 1980. Vitamin C content and distribution in mangoes during

ripening. J. Food Technol., 15: 669-72.

Tian, M.S., A.B. Woolf, J.H. Bowen and I.B. Ferguson. 1996. Changes in color and

chlorophyll fluorescence of broccoli florets following hot water treatment. J.

Amer. Soc. Sci., 121: 310-313.

Tucker, G.A. and D. Grierson. 1987. Fruit ripening. In: Davies, D. (Ed.). The

Biochemistry of Plants. Academic Press Inc., New York. 12: 265-319.

UN, 2003. Organic Fruit and Vegetables from the Tropics. United Nations Conference on

Trade & Development. New York and Geneva.

212

Valley, S. 2000. Sun-dried tomato-the valley sun difference. Newman, Calif. Available

from: http://www.valleysun.com. Accessed 2001 Jan 1.

Van Schaftingen, E. and D.R. Davies. 1991. Fructose administration stimulates glucose

phosphorylation in the livers of anesthetized rats. Faseb J., 5(3): 326-330.

Vandercook, C.E. S. Hasegawa 1980. V.P. Maier. Dates. In: Nagy, S; Shaw, P.E. (Eds.)

Tropical and Subtropical Fruits. AVI Publishing Co: Westport, CT, P. 506-541.

Vandercook, C.E., S. Hasegawa, and V.P. Maier.1980. Dates, p. 506-541. In: S. Nagy and

P.E. Shaw (Eds.). Tropical and subtropical fruits: Composition, properties, and

uses. AVI Pub-lishing Company, Westport, CT.

Vayalil, P.K., 2012. Date Fruits (Phoenix dactylifera Linn): an emerging medicinal food.

Crit. Rev. Food Sci. Nutr., 52: 249-271.

Walker, A.J. and L.C. Ho. 1977. Carbon translocation in tomato-effects of fruit

temperature on carbon metabolism and rate of translocation. Ann. Bot., 41:

825-832.

Wall, M.M. 2004. Ripening behaviour and quality of `Brazilian' bananas following hot

water immersion to disinfest surface insects. HortScience, 39: 1349-1353.

Wang, Z.Y. and D.R. Dilley. 2001. Aminoethoxyvinylglycine, combined with ethephon,

can enhance red color development without over-ripening apples. HortScience,

36: 328-331.

Warner, H.L. and A.C. Leopold. 1967. Plant growth regulation by stimulation of ethylene

production. Biol. Sci., 17: 722.

Watada, A.E., R.C. Herner, A.A. Kader, R.J. Romani and G.L. Staby. 1984. Terminology

for the description of developmental stages of horticultural crops. Hort. Sci.,

19: 20-21.

Watford, M. 2002. Small amounts of dietary fructose dramatically increase hepatic

glucose uptake through a novel mechanism of glucokinase activation. Nutr.

Rev., 60: 253-257.

Whale, S.K., Z. Singh, M.H. Behboudian, J. Janes and S.S. Dhaliwal. 2008. Fruit quality

in „Cripp‟s Pink‟ apple, especially colour, as affected by pre-harvest sprays of

aminoethoxyvinylglycine and ethephon. Sci. Hort., 115: 342-351.

White, P.J. 2002. Recent advances in fruit development and ripening: an overview. J.

Exp. Bot., 53: 1995-2000.

213

Wicks, A.S. and W.M. Kliewer. 1983. Further investigations into the relationship

between anthocyanins, phenolics and soluble carbohydrates in grape berry

skins. Amer. J. Enol. Viticul., 34: 114-116.

Wills, R.B.H. and G.H. Kim. 1995. Effect of ethylene on post-harvest life of strawberries.

Post-harvest Biol. Technol., 6: 249-255.

Worku,, Z., R.C. Herner, and R.L. Carolus. 1975. Effect of stage of ripening and

ethephon treatment on color content of paprika pepper. Sci. Hort. 3: 239-245.

Wrigley, G. 1995. Date palm, In: J. Smartt and N.W. Simmonds (Eds.). Evolution of crop

plants. 2nd ed. Longman Group, Essex, UK. P. 399-403.

Yadava, L.P., R. Pati and V.K. Gupta. 2008. Effect of paclobutrazol and ethephon on the

biochemical constituents of cape gooseberry (Physalis peruviana L.). Asian J.

Biol. Sci., 3: 124-126.

Yang, S.P. 1985. Biosynthesis and action of ethylene. HortScience, 20: 41-45.

Yong, R., O. John, W.C. Cooper and J.J. Smooth. 1970. Pre-harvest sprays with 2-

chloroethylphosphonic acid to degreen „Robinson‟ and „Lee‟ tangerine fruits.

Hort. Sci., 5: 268-279.

Yousif, A.K., A.F. Alshaawan M.Z. Mininah and S.M. Eltaisan. 1987. Processing of date

preserve, date jelly and date butter. Date Palm J., 5: 73- 86.

Yuzo, S. and Y. Tomoya. 2002. Effect of ethephon agent spray on fruit quality of 'la

France'. Tohoku Agric. Res., 55: 161-162.

Zaid, A. 1999. Date palm Cultivation. FAO. Publication. No. 287.

Zaid, A. and E.J. Arias-Jimenez, 2002. Date Palm Cultivation. FAO Plant Production and

Protection Paper 156 (Rev. 1). FAO, Rome, Italy.

Zare, Z., M. Sohrabpour, T.Z. Fazeli and K.G. Kohan. 2002. Evaluation of invertase (B-

fructo furanosidase) activity in irradiated Mazafati dates during storage. Radiat.

Phys. Chem., 65: 289-291.

Zohary, D. and M. Hopf. 2000. Domestication of plants in the Old World. The origin and

spread of cultivated plants in West Asia, Europe, and the Nile Valley. Oxford

University Press, Oxon, UK.

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