Plant Growth Regulators in Quality Vegetable Production

Haripriya.S

ICAR-Krishi Vigyan Kendra, Tamil Nadu Agricultural University, Vriddhachalam

Plant growth regulators (also known

as growth regulators or plant

hormones) are chemicals used to alter

the growth of a plant or plant part.

Hormones are substances naturally

produced by plants, substances that

control normal plant functions, such as

root growth, fruit set and drop, growth

and other development processes.

Naphthyl acetic acid (NAA) does not

occur naturally. NAA treatment

induces parthenocarpy of fruits in

tomatoes, ladies finger and brinjal.

Triacontanol is a fatty alcohol known

as melissyl alcohol or myricyl alcohol.

It is commonly found in waxy plant

cuticles and in beeswax. The latest

researches suggest that triacontanol

directly activates the genes that control

photosynthesis. These genes in turn

activate the enzymes controlling the

chemistry of photosynthesis.

Ethylene is the only gaseous

hydrocarbon hormones which plays

an important role in the ripening of

fruits, inhibition of root growth,

abscission and other growth processes.

Ethrel treatment has been found to

change sex expression in cucurbits,

and pepper.

Maleic hydrazide functions as a

growth regulator acting especially on

root vegetables. Maleic hydrazide is

applied as over-the-top foliar spray

when the foliage is still in a good

condition. Routinely, it is also used as

a sprouting inhibitor during storage.

Tender coconut water (CW) is a rich

supplement that naturally contains

plant growth regulators such as Indole

Acetic Acid (IAA). They can also be

used to promote uniform flowering, to

promote fruit set, and to prevent

premature fruit drop.

Table 1. Plant growth regulators used during inter-cultural operations in

vegetable production

Crop Plant Growth

Regulator

Dosage Time of spray Remarks

SOLANACEOUS VEGETABLES

Tomato

Triacontanol

NAA

1.25 ml/l of

water

0.25 ml/l of

water

30 , 60 DAT

70, 90 DAT

Anti-

transpirant

Reduces

flower and

fruit drop

Brinjal Triacontanol

NAA

1.25 ml/l of

water

0.25 ml/l of

water

20, 35 DAT

60,90, 120 DAT

Anti-

transpirant

Reduces

flower and

fruit drop

Chilli Triacontanol

NAA

1.25 ml/l of

water

0.25 ml/l of

water

20, 40, 60, 80 DAT

60, 90 DAT

Anti-

transpirant

Reduces

flower and

fruit drop

Capsicum

and paprika

Triacontanol

Planofix

1.25 ml/l of

water

0.25 ml/l of

water

30,60, 90 DAT

70, 85 DAT

Anti-

transpirant

Reduces

flower and

fruit drop

CUCURBITS

Watermelon

Ethrel

2.5 ml/10l of

water

2 true leaf stage ( 15

DAS) 3 times @ 1

week interval

Modification

of sex

expression

Cucumber

Ethrel 2.5 ml/10l of

water

2 true leaf stage( 15

DAS) 3 times times

@ 1 week interval

Modification

of sex

expression

GOURDS

Bitter gourd

Ethrel 2.5 ml/10l of

water

2 true leaf stage( 15

DAS) 3 times times

@ 1 week interval

Modification

of sex

expression

Ridged

gourd

Ethrel 2.5 ml/10l of

water

15 DAS

4 times times @ 1

week interval

Modification

of sex

expression

Snake

gourd

Ethrel 1 ml/10l of

water

2 true leaf stage(

after the climber

reached its top) 4

times times @ 1 week

interval

Modification

of sex

expression

Pumpkin

and Ash

gourd

Ethrel 1 ml/10l of

water

15 DAS

4 times times @ 1

week interval

Modification

of sex

expression

TUBEROUS CROP

Onion Maleic

hydrazide

500 mg/l of

water

15 days before

harvesting

Avoid early

sprays before

maturity to

reduce spongy

onions

OTHER CROPS

Okra Tender

coconut water

10 % spray 30th DAS @ 15 days

interval

(Rainy or severe

winter season)

Increases fruit

set and fruit

yield during

rainy or

severe winter

season

DAT – Days after Transplanting; DAS – Days after Sowing

(Source: Tamil Nadu Precision Farming Technologies, 2008)

Foliar spraying of PGR’s as specified

in Table 1. during the crop

intercultural operations would be

beneficial in enhancing the yield and

quality of the vegetables. Vegetables

contribute to the food and nutritional

security of the people in both the

developed and developing countries.

By adopting such inter-cultural

operations, a remarkable change in

production and nutritional quality of

the vegetables can be assured.