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A STUDY OF THE VEGETATIVE AND REPRODUCTIVE MORPHOLOGY OF

GRASSLANDS HUlA WHITE CLOVER (7�itofium �epen� L.) WITH

EMPHASIS ON THE EFFECTS OF DEFOLIATION AND PARAQUAT

ON SEED YIELD AND QUALITY

CARLOS EDUARDO ROMERO MALDONADO

1985

Depicting vegetative and floral parts of white

clover plant.

Inflorescence

Seed Pod Single Seed

ABSTRAC T

The p r e s ent s t udy e x amined t h e e ffect of management s y s t ems , p ar t i cul ar l y

cl osi ng dat e and paraquat app l i ca t i on, o n t h e vege t a t i ve and r e product i ve

morphol ogy of'Gr a s s l and s Hui a' whi t e clover (Tri fol i um repens L. ) ove r

two succe s s i ve y e a r s i n a fi e ld mi x e d (gra s s and clover ) sward s i t uat i on.

More d e t ai l e d s tudi e s i nvolv i ng two di f fe rent genoty p e s of 'Gr a s s l ands

Hui a' whi t e clover grown i n monocul ture were al so carri ed out to e x am i ne

the e f fect s of cut t i ng and paraquat app l i cat i on.

The mi x e d sward s t udi e s cl ear l y showe d t h at N ovember closing d at e s

r e s u l t e d i n h i gh e s t s e e d y i e l d s. I n gr a s s/clover swards the clos i ng

of crQp s i n November accomp ani ed by p araquat s pray i ng to remove gra s s

comp e t i t i on e i t h e r i n mi d Oct obe r or at clos i ng , enhance d seed y i e l d.

Lat e r grazi ng and s p r ay i ng was d e l e t e r i ou s t o s e e d y i e l d unle s s c l i m at i c

condi t i ons al l ow e d cont i nued vege t at i ve grow t h into December. I n t h i s

lat t e r cas e s p r ay i ng i n November and clos i ng i n December gave h i gh s e e d

yi e l d s . Tr e atment s i nvol v i ng closing i n Se p t ember and October and

spray i ng 30 day s before , at clos i ng or 30 day s a f t er closi ng , alway s

gav e l e s s s e e d y i e l d t han November t r e atme nt s spray e d 30 day s be fore or

at closing t i me.

Closing t i m e and s p r ay i ng t i me had a mar k e d e ffect on seed y i e l d component s.

The mos t cons i s t ent and major ef fect of c l os i ng and s p r aying t r e atment s

i n t h e two m i x e d sward experiment s was on i nf l ore sce nce number s. O t h e r

component s such a s s e e d s e t , s e e d weigh t , and f l or e t numbers w e r e not

cons i st ent l y i nf l uenced by management but di d v ary according to e nvi ron­

men t a l condi t i ons.

Studi e s on the e f fect s of cut t i ngs and p ar aquat ap p l i cat i on on p l ant

s t ructure and on s e e ding pot ent i al and y i e l d of 'Gr a s s l ands Hui a' whi t e

clove r cl e ar l y showe d t h a t t here i s a p a r t i t i oni ng between v e ge t at i v e

grow t h and r e product i ve d e v e l opment. The v e ge t a t i v e proce s s w a s charac­

t eri s e d by a h i gh p ercent age of t h e nod e s on mai n s t olons formi ng l at eral

s t olons i n t h e wi nt e r and ear l y s pri ng. R e product i ve deve l opment i n l at e

spr i ng and summe r showed t h a t approxi mat e l y 80% o f i nf l ore scence s were

forme d on mai n s t o lons . High e s t i nf l ore scence number s were p roduced

from nodes forme d i n Octobe r and Novembe r , a l t hough f l oral i ni ti at i on

s t ar t e d duri ng l a t e wint e r (August ) . The two genot y p e s used i n t h i s

s t udy show e d consi derabl e vari a t i on i n r e l at i on t o reproduct i ve d e v e l op­

ment . Di f ference s of 47% i n i nflore scence number s , 25% i n s e e d s p e r

f l or e t and 13% i n s e e d w e i gh t w e r e obs e r v e d between genotype s.

The e f fe c t s of defoli at i on by cut t i ng i nvolved a re ducti on i n stolon

e l ongat i on and a gener a l i ncr e a s e i n l at eral s t ol on product i on ,

part i cul a r l y when t ermi nal bud s w e r e a l so removed. Both l i gh t and

he avy cut t i ng t r e atment s r e sul t e d i n s e e d yi e l d s whi ch were 70 to 90 kg/ha l e s s t han the 657 kg/ha produce d by uncut p l ant s. The e f f ect of

p araquat app l i cat i on was al so d e t rimental to s e e d yi e l d , mai nly t hrough

a di rect e ffect on whi t e clover morphology. A l though p ar aquat reduce d

t h e amount o f l at eral branchi ng on t h e main s t olon t h e de s t ruct i on of

s t ol on t i s sue by t h e h erbi ci de r e duce d p l ant r e covery and r e su l t e d i n

a s e e d y i e l d o f onl y 392 kg/ha compare d wi t h 657 kg/h a from unspray e d

p l ant s. Thi s e f f ect was mos t pronounce d in pure swar d s of whi t e clover

and was l e s s obvious when the gra s s component of a mi x e d sward provi d e d

some prot ect i on for t h e whi t e clover by re ducing t h e e x t ent o f di rect

cont act wi t h t h e herbi ci de.

Some pot e nt i al are a s for future r e s e arch and t h e p ot e nt i al for whi t e

clover s e e d producti on i n Colombi a are also di s cu s s ed.

ii

ACKNOWLEDGEMENTS

There are many people I wish to thank for thei r understanding and

s upport during my studies in New Zealand .

but I thank them al l .

I can mention on ly a few

Those pr incipa l l y invol ved were :

Dr Murray H i l l , Di rector

beginning of my research

read and corrected the

constructive cr iticism .

o f the Seed Technology Centre who s i nce the

ha s been a source of he lp and support . He

manus cript improving my e ngl i sh a nd making

Professor B . R . Watki n , Head of the Department of Agronomy who guided

and instructed me during the first part of the research work .

Dr M . P . Rol ston , of the Gra s s lands Divis ion , DSI R , who provided guidance

a nd he lp during the programme .

Professor R . G . Thoma s for hi s inva luable and constant help during the

preparation of this thesis . His support is very much apprec iated .

I a l so thank Mrs D . Meech , Mrs K . Johnstone , Mr s R . Ca lton,

Johnstone and Mr G . Wa l ter for their technical a ssistance

l aboratory work and in the s canning electron mi crographs .

Mr R . C . Seddon for his help in computing the data .

Mr C . R .

i n the

Sta f f and students of Seed Technology Centre and the technicians of

the Agronomy Department , especi a l l y Mr T . J . Lynch, Mr M. C . Thomson

and Mr R . F . Battersby for the i r support and the use of the ir technica l

faci lities .

Mrs Anne Davies for her patience a nd care in typing the draft of

the manuscr ipt .

Mrs Veronica Fi.e ldsend for her care in the f ina l typing of the manuscript .

i i i

My gratitude i s a l so expressed to the New Zeal and a nd Colombia n

Governme nts who al lowed me t o complete m y study programme .

Fina l l y , my warmes t thanks to Maria Isabel , Car los and Cami lo for thei r

patience , support and understanding .

iv

CONTENTS

PAGE

Abstract

Acknowledgements i i

List of Tables vi i i

List of Figures xii

List of Plates xiv

List of Appendices XV

INTRODUCTION �·

CHAPTER I - REVIEW OF LITERATURE 4

A - General Descr ipt ion of White Clover 4

B - Vegetative Morphology and Growth · 6

1 - Stolen Structure and Growth 6

2 - Branching 9 3 - Leaf and Petiole Growth 10

4 - Root Growth 11

C - Reproduct ive Morphology and Growth 12

1 - Inflorescence St ructure and Growth 12

2 - Fac� which af fect Inf lorescence Deve lopment 13

D - Ef f ect of Flowering on Vegetat ive Growth 16

E - Seed Structure and Development 16

F - Seed Yield Components and Seed Qua l i ty 20

G - Seed Crop Management 23

1 - Seed Product ion 23

2 - Effect of De fol iation on Vegetat ive Growth , Reproductive Growth and Seed Product ion 28

H - Paraguat Properties 32

CHAPTER II - EFFECT S OF CLOSING DATE AND TIMING OF PARAQUAT AP PLICATION ON VEGETATIVE AND REPRODUCTIVE GROWTH OF HUIA IN MIXED SWARD S 33

A - Field Experiment 1982 - 1983 33 1 - Int roduction 33

2 - Materia l s and Methods

a - Experimenta l Site and Field Procedures

b - Plant Measurements and Stati sti cal Ana lysis

3 - Results

a - Ef fect of Treatments on Dry Weight of grass and Dead Matter

b - Ef fect of Treatments on Whi te Clover Dry Wei ght

c - Ef fect of Treatments on Clover Lea f Area Index

d - Ef fect of Treatments on Number of Nodes and Terminal Buds

e - Ef fect of Treatments on the Date of Peak F l owering

f - Effect of Treatments on Seed Yield and Yield Components

g - E f f ect of Treatments on Seed Quality

h - Relationship Between Seed Y i eld and Yield Components

B - Field Exper iment 1983 - 1984

1 - Introduction

2 - Materia l s and Methods

a - Experimenta l Site and Field Procedure

b - Pl ant Measurements and Stati stical Ana lysis

3 - Re sults

a - Ef fect of Treatments on Gra s s and Dead Matter Dry Weight

b - E f f ect of Treatments on White Clover Dry We ight

c - Ef fect of Treatments on White C lover Leaf Area I ndex a nd Lea f let Area

d - Ef f ect of Treatments on Number of Nodes , Terminal buds and Stolon Length

e - Ef f ect of Treatments on Branch Production per Stolon

f - Re l ationship between Vegetat ive Characters

g - Ef fect of Treatment on the Number of I n f l orescences

h - Re lationship between Inf lorescences/m2

a:nd Vegetative Characters

i - Effect of Treatments on the Date of Peak F l owering

V

PAGE

33

3 3

37

3 9

3 9

42

4 5

47

50

50

61

65

67

6 7

6 7

6 7

70

·10

70

n

75

7 7

82

92

85

B:Z

90

j - Ef fect of Treatments on the Seed Yield and Yield Components

k - Ef fect of Treatment on Seed Qua l ity

l - Rela tionship between Seed Yield and Yield Components

C - Di scus sion

C HAPTER I ll - STUDY OF THE GROWTH PATTERN OF HUlA AND

THE EFFECT OF C UTTING AND PARAQUAT ON ITS

REP RODUCTIVE DEVELO PMENT AND SEED Y I ELD

A - The Importance of Pl ant Structure on Seeding Potent ial

and Yield

1 - Int roduction

2 - Materials and Methods

a - Experimenta l Site and Field Procedures

b - Plant Meas urements

3 - Res ults

a - Vegetative Growth and Development

b - The Morphology of I n f lorescence Initiat ion and Development

c - Seed Yield and Seed Y i e ld Components

4 - Di scuss ion

B - E f f ect of Paraquat Appl i cation and Cutting Intensity on

Reproductive Growth and Seed Y ield

1 - Materials a nd Methods

a - Exper imenta l Site and Field Procedures

b - Pl ant Measurements and Statistica l Ana lys i s

2 - Res ults

a - Ef fect of Defol iation Treatments on Wh ite Clover Vegetative Growth and Development

b - Ef fect of Defol iation Treatments on Wh ite Clover Reproduct ive Growth a nd Devel opment

c - Effect of Defoliat ion Treatments on \'lhi te Clover Yield Components and Seed Yield

d - Effect of De fol iation Treatments on White Clover Seed Qual ity

3 - Discussion

vi

PAGE

91

97

101

102

109

10':1

109

110

110

112

115

115

124

141

1 44

146

147

147

148

149

149

158

162

167

167

,•

- .

CHAPTER IV - GENERAL DISCUSSION

- CONCLUSIONS

APPENDI CES

BIBLIOGRAPHY

vii

PAGE

171

179

1 8 3

208

TABLE

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

1 6

LIST OF TABLES

Treatments used and their identification 1982/83

Effect of closing time a�d paraquat treatments on grass dry weight (g/m )

Effect of closing time and par�quat treatments on dead matter dry weight (g/m )

Effect of closing time and para�uat treatments on white clover dry weight (g/m )

Effect of closing time and paraquat treatments on white clover leaf area index

Effect on closing time an� paraquat treatments on the number of nodes/dm

Effect of closing time and paraqu�t treatments on the number of terminal buds/dm

Effect of closing time and paraquat treatments on the date of peak flowering

Effect of closing date and time of paraquat application on seed yield per unit area (kg/ha)

Effect of closing date and time of paraquat a�plication on the total number of inflorescences/ m present at each harvest

Effect of closing date and time of paraquat application on the number of florets per inflorescence at peak flowering

Effect of closing date and time of paraquat application on the seed number per floret present at each harvest

Effect of closing date and time of paraquat application on 1000 seed weight (g) at each harvest

Correlation coefficients between seed yield (kg/ha) and yield components

Treatments used and their identification

Effect of closing date and time of p�raquat application on grass dry weight (g/m )

viii

PAGE

37

40

41

4J

46

48

49

52

55

57

58 '

60

66

68

71

TABLE

17

18

19

20

21

22

23

24

Effect of closing date and time of paraqua� application on dead matter dry weight (g/m )

Effect of closing date and time of paraquat2 application on white clover dry weight (g/m )

Effect of closing date and time o� p�raquat application on leaf area index (m /m )

Effect of closing date and time2of paraquat application on leaflet area (mm )

Effect of closing date and time of pa2aquat application on the number of nodes/dm

Effect of closing date and time of paraquat applica1ion on the number of terminal buds/dm

Effect of closing date and time of paraquat application on the length (mm) of main stolon

Effect of closing date and time of paraquat application on the number of branches per stolon

25 Effect of closing date and time of paraquat application on the strength of2association between clover dry weight (g/m ) and some vegetative characters measured every 15 days after the completion of each treatment until harvest

26

27

28

29

3 0

Effect o f closing date and time o f paraquat application on t�e total number of inflorescences/m

Correlation coefficient for eac� treatment between inflorescence numbers/m emerged at different time of the year and several vegetative characters of white clover plants

Effect of closing date and time of paraquat application on the date of peak flowering

Effect of closing date and time of paraquat application on seed yield (kg/ha)

Effect of closing date and time of paraquat 2 application on the number of inflorescences/m at harvest

ix

PAGE

73

74

76

78

79

80

81

83

84

85

87

90

91

-93

TABLE

31

32

33

34

35

36

37

38

Effect of closing date and time of paraquat application on the number of florets per inflorescence at harvest ·�

Effect of closing date and time of paraquat application on the number of seeds per floret at harvest

Effect of closing date and time of paraquat application on 1000 seed weight (g)

Effect of closing date and time of paraquat application on normal seedling percentage

Effect of closing date and time of paraquat application on abnormal seedling percentage

Effect of closing date and time of paraquat application on hard seed percentage

Effect of closing date and time of paraquat application on dead seed percentage

Correlation coefficients between seed yield and yield components from plots closed at different dates and sprayed with paraquat

39 Total number of nodes, lateral stolons, lateral branches, axillary buds, and inflorescences present in February at the nodes, which emerged from terminal buds of main stolons from July to January

40

41

42

Changes in petiole and peduncle length, inflorescence size, and number of ovules per floret with the time of the year

Variation in yield components and seed yield between two 'Grasslands Huia' genotypes

Treatments used and their identification

43 Effect of defoliation treatments on the number of nodes emerging from the terminal bud per month on a main stolon from November to January

44 Effect of defoliation treatments on the increment in length (mm) of a main stolon during each month from November to January

X

PAGE

94

95

96

97

98

99

100

101

119

139

141

148

150

151

xi

TABLE PAGE

45 Effect of defoliation treatments on the number of leaf primordia per terminal bud

46 Effect of defoliation treatments on the number of lateral stolons present in February at nodes which emerged from teriminal buds of main stolons during each month from November to January

47 Effect of defoliation treatments on the number of lateral branches present in February at nodes which emerged from terminal buds of main stolons during each month from November to January

48 Effect of defoliation treatments on the number of rooted notes present in February at nodes which emerged from terminal buds of main stolons during each month from November to January

49 Effect of defoliation treatments on the number of inflorescences present in ten terminal buds of main stolons every 15 days from November to January

50 Effect of defoliation treatments on the time of inflorescence initiation in ten terminal buds of main stolons every 15 days from November to January.

51 Effect of defoliation treatments on the total number of inflorescences emerged

52

53

on main stolons plus lateral stolons, present in February at nodes which emerged from terminal buds during each month from November to January

Effect of defoliation treatments on white clover yield components

Effect of defoliation treatments on white clover seed yield (kg/ha)

54 Effect of defoliation treatments on white clover seed quality

154

156

157

158

159

160

161

164

166

168

FIGURE

1

2

3

4

5

6

7

8

9

10

11

LIST OF FIGURES

Vegetative and floral parts of a white clover plant

a) External and internal morphology of a legume seed and

b) Anatomical features of a legume seed coat

Trial layout. Field experiment 82/83

Effect of closing time on the percentage of normal seedlings, abnormal seedlings, hard seed, dead seed and viable seed at each harvest

Effect of paraquat spraying time on the percentage of normal seedlings, abnormal seedlings, hard seed, dead seed and viable seed at each harvest

Trial layout. Field experiments 83/84

Effect of closing t�me and paraquat treatments on seed yield .!g/m ) Two year experiments

Vegetative and floral organs of a white clover plant

Number of nodes emerging from the terminal bud on main stolons per month

Monthly incremental length increase in main stolons (July to January)

Total number of lateral stolons present in February at nodes which emerged from terminal buds on main stolons from July to January

12 Number of lateral stolons of different lengths present in February at nodes which emerged from terminal bud of twenty main stolons from July to January

13 Number of lateral branches and axillary buds present in February at nodes which emerged from terminal buds of main stolons from

14

July to January

Percentage of rooted nodes present in February at nodes which emerged from terminal buds of main stolons from July to January

xii

PAGE

17

35

62

63

69

106

111

116

117

118

121

122

123

FIGURE

1 5

1 6

1 7

1 8

1 9

2 0

Diagramatic representation of stages of inflorescence and node development in white clover relative to distance from stolon apex under natural spring conditions. Thomas ( 1 981 )

Estimated time of inflorescence initiation in 1 0 terminal buds on main stolon from July to February

Number of inflorescences present in ten terminal buds on main stolons from July to February

Number of inflorescences emerged on main stolons and lateral stolons from September to January

Number of white inflorescences present per unit area

Number of white inflorescences produced in paraquat and cutting treatments

xiii

PAGE

125

132

133

1 3 5

1 3 7

1 6 3

LIST OF PLATES

PLATE

1 Knapsack sprayer used for paraquat application

2 Portable shearing machine used in cutting treatments

3

4

5

6

7

8

9

10

11

Damage caused by paraquat in white clover leaves one week after spraying

Damage caused by paraquat application to white clover inflorescence one week after spraying

Scanning electronmicrograph showing the morphological appearance of a leaf primordium (x 550)

Scanning electron micrograph showing flower initiation (x 430)

Scanning electron micrograph showing floret initiation (x 300)

Stage of growth of an inflorescence at early emergence (x 60)

Stages of development of inflorescences after emergence

Differences in flowering density between the two genotypes in December 1984

Ovules present in an unfertilised floret (x 60)

12 X-ray photograph showing changes in the number of ovules forming seeds in individual florets

13

14

Effect of heavy cut and paraquat treatments on main stolons of white clover 7 days after treatment application

Recovery growth of white clover stolon after paraquat application

xiv

PAGE

34

36

89

89

126

127

128

130

130

136

140

142

152

155

LIST OF APPENDICES

APPENDICES

1

2

3

4

5

6

7

8

9

10

1 1

12

13

Soil analysis of the experimental field

Basic weather data for Palmerston North; mean values for each month over the experimental period 1 982 - 1983

Effect of closing time and paraquat treatment on soil moisture content 1982-1983

Effect of closing time and paraquat treatment on normal seedling percentage 1 982-1983

Effect of closing time and paraquat treatments on abnormal seedling percentage 1982-1983

Effect of closing time and paraquat treatments on hard seed percentage 1 982-1983

Effect of closing time and paraquat treatments on dead seed percentage 1982-1983

Effect of closing time and paraquat treatments on viable seed percentage 1982-1983

Basic weather data for Palmerston North: mean values for each month over the experimental period 1983-1984

Effect of closing time and paraquat treatments on soil moisture content 1 983 - 1 984

Variation in number of florets in ten inflorescences at harvest 1983-1984

Basic weather data for Palmerston North: mean values for each month over the experimental period 1 984 - 1985

Increase in length of main stolons from July to January 1984-1985

14 Number of lateral stolons of different sizes present in February on main stolons from July to January 1 984-1985

1 5 Percentage of rooted nodes present in February at nodes which emerged from terminal buds of main stolons from July to January 1984-1985

XV

PAGE

1 83

184

185

1 86

187

188

189

190

191

192

193

194

195

196

197

APPENDICES

16

17

1 8

1 9

20

21

22

23

24

25

Estimated time of initiation of inflorescences in 10 terminal buds of main stolons from July to January 1984-1985

Number of inflorescences present in ten terminal buds on main stolons from July to January 1984-1985

Number of inflorescences on main and lateral stolons, present in February, on nodes which emerged from terminal buds on main stolons from September to January 1984-1985

Number of white inflorescences per unit 1 984-1985 area

Changes in petiole and peduncle length, inflorescence size, number of ovules per ovary, and seed numbers per pod in Genotype I and Genotype II 1984-1985

Effect of defoliation on the number of inflorescences per main stolon present in February at nodes which emerged from terminal buds of main stolons from November to January 1984-1985

Effect of defoliation on the number of inflorescences on lateral stolons present in February at nodes which emerged from terminal buds on main stolons from November to January 1984-1985

Effect of defoliation on the number of florets per inflorescence 1984-1985

Effect of defoliation on the number of ovules per ovary 1984-1985

Effect of defoliation on the number of seeds per floret 1984-1985

�i

PAGE

198

199

200

201

202

203

204

205

206

207