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 Dosage Time of spray Regulator SOLANACEOUS VEGETABLES Tomato Triacontanol 1.25 ml/l of 30 , 60 DAT water NAA
0.25 ml/l of 70, 90 DAT water
Remarks
Antitranspirant Reduces flower and fruit drop
Brinjal
Chilli
Triacontanol
1.25 ml/l of 20, 35 DAT water
Antitranspirant
NAA
0.25 ml/l of 60,90, 120 DAT water
Triacontanol
1.25 ml/l of 20, 40, 60, 80 DAT water
Reduces flower and fruit drop Antitranspirant
NAA
0.25 ml/l of 60, 90 DAT water
Capsicum Triacontanol and paprika Planofix
1.25 ml/l of 30,60, 90 DAT water
Reduces flower and fruit drop Antitranspirant
0.25 ml/l of 70, 85 DAT water
Reduces flower and fruit drop
2.5 ml/10l of 2 true leaf stage ( 15 water DAS) 3 times @ 1 week interval 2.5 ml/10l of 2 true leaf stage( 15 water DAS) 3 times times @ 1 week interval
Modification of sex expression Modification of sex expression
2.5 ml/10l of 2 true leaf stage( 15 DAS) 3 times times water @ 1 week interval 2.5 ml/10l of 15 DAS water 4 times times @ 1 week interval 1 ml/10l of 2 true leaf stage( water after the climber reached its top) 4 times times @ 1 week interval 1 ml/10l of 15 DAS water 4 times times @ 1 week interval
Modification of sex expression Modification of sex expression Modification of sex expression
CUCURBITS Watermelon Ethrel Cucumber
Ethrel
GOURDS Ethrel Bitter gourd Ethrel Ridged gourd Snake gourd
Ethrel
Pumpkin Ethrel and Ash gourd
Modification of sex expression
TUBEROUS CROP Onion Maleic hydrazide
500 mg/l of 15 days water harvesting
OTHER CROPS Okra Tender coconut water
10 % spray
30th DAS @ 15 days interval (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.
intercultural
during
operations
the would
crop 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.
before Avoid early sprays before maturity to reduce spongy onions Increases fruit set and fruit yield during rainy or severe winter season
