21. PRACTICAL APPLICATION OF PLANT GROWTH REGULATORS
IN CROP PRODUCTIVITY
Commercial uses of growth regulators
1. Rooting and plant propagation
a) Auxin compound like IBA NAA, 2,4-D, 2, 4,5-T
b) IBA produces strong fibrous root system
2. Germination and dormancy
a) Gibberellin is a potent germination promoter
b) Abscissic acid – germination inhibitor (Anti – Gibberellin)
c) Induce Dormancy - ABA
d) Breaking of dormancy - Auxins and Gibberellin
3. Fruit set and Development
a) Fruit setting → 2, 4, 5 – T
b) Fruit size increment in grapes → Gibberellic acid
c) Shelf life increment in fruits and flowers → Cytokinin
d) Good fruit shape ------ Gibberellic acid + Cytokinin
e) Parthenocarpic fruit – Gibberellins, IAA and PAA
4. Sex expression
Production of male flowers → Gibberellins (cucumber)
Production of female flowers → Auxins and Gibberellins
↓ ↓
Cucumber maize
5. Abiscission
Control of abscission → NAA and IAA
Induce Abscission → Ethrel
6. Morphogenesis
Auxin and Cytokinin
7. Weed control
2, 4-D and 2, 4, 5-T
8. Plant organ size
Increases plant height → GA
Shorten the plant height → TIBA
↓
Tri iodo benzoic acid
Increases Tillering → Cytokinin
Ex: BAP (Benzyl amino purine) and TIBA
9. Antitranspirants → ABA and PMA
↓
Phenyl mercury acetate
10. Papaya Later flow → Ethephon
11. Rubber latex flow → 2, 4 – D and 2, 4,5 – T
12. Fruit ripening → Ethrel
13. Sugarcane ripeners → Glyphosphate and CCC
