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.