Use of Growth Regulators in Horticultural Crops
They are applied in the form of paste and solution. The concentration of the chemical varies with plant species and types of cutting and method of application.
Rooting in stem cutting 9 Hard to root).
IAA, IBA, and NAA.
a) Soak Method:
10 to 100 ppm for 12 -24 hrs called soak method.
b) Quick Dip Method:
1000to 5000 ppm for 5 seconds. Some G.R are used in layering, grafting and budding for getting high success.
2. Seed Germination:
GA significantly accelerates seed germination in many plant species. Pre soaking the seed with G. Such as bhendi and sugar beet increase germination.
3. Induction of Flowering:
Plant growth regulators like NAA at 10 to 50 ppm causes early flowering in pine apple. 2, 4 D at 6 to 10 ppm has used to induce flowering in pine apple. Flowering can be delayed by 1 to 2 weeks NAA at 200 to 800 ppm application in apple, cherries, pears, peaches, and plums.
4. Sex Expression:
Plant growth regulators can change the sex of the flowers. Male sterility can be induced in corn by MH 9 malic hydrozide). It is used in plant breeding for induction of male sterility. Application of NAA, IAA and GA at 50 to 100 ppm increases female flowers in pumpkin, cucumber to get more yield.
5. Flower and Fruit Thinning:
Many fruit trees produces heavy flowering and fruit in one year and few or one in next year. By using G.R the normal bearing can be maintained NAA at 5 to 10 ppm and NAA at 5 to 7 ppm for thinning of apple, peaches and grapes.
6. Pre Harvest Drop of Fruits:
Flower and fruit drop is a problem in many fruit crops. Application of NAA 10- 50 ppm in mango, citrus and chilies reduce fruit drop by preventing formation of abscission layer.
7. Fruit Development:
Application of 50- 100 ppm GA in grapes increases the berry size.
8. Early Maturity:
Early maturity fetches higher prices in the market. In pine apple application of 20 ppm NAA induces early flowering and early maturing at least by two months. Spraying of 50 ppm NAA reduces maturity in grapes, use of 250 – 400 ppm of Ethrel induces early maturity in Ber.
9. Early Ripening and Colour Development:
Fruits like mango, banana, papaya ripes after harvest. Dipping of fruits in 20-50 ppm Ethrel solution induces golden yellow colour to fruit induces early maturity.
10. Delayed Maturity:
Delay in ripening is required when fruit are to be sent to long distance market. Dipping of fruit in 2,4-D, 2,4- 5- T or MH- 40 extends storage life of fruits.
11. Sprouting of Bud:
Ethrel, GA, thio urea, IBA and Cyotkininn, spray induces sprouting of buds.
12. Braking of Dormancy:
GA, Ethrel, NA are used in breaking dormancy in seeds and buds.
1. Bulk Pruning: Removal of large limbs as contrasted to removal of larger number of small branches.
2. Crotch: The angel made by the attachment of a branch.
3. Deheading: a server hesing back of major limbs of a tree.
4. Fine Pruning: Removal of small branches or twing over the entire plants as contrasted to removal entire plants limbs.
5. Heading Back: Removal of a large amount of wood from the plant. This may be either coarse or fine.
6. Leader: the most prominent and upright branch through the center of the tree which tends to dominate all others.
7. Pruning: The removal of plant parts for the purpose of increasing the value of the reamaing parts.
8. Scaffold Branch: The main branches arising difficulty from the trunk of the tree.
9. Secondary Branches: The main branches arising from the main branch.
10. Shoots: New growth which bears leaves.
11. Spur: A shoot or twing of limited growth.
12. Thinning Out: Removal of an entire twing or branch at its point of origin.
13. Modification of form or shape by pruning:
14. Trunk: The main axis of the plant from ground level to the point of branching.
15. Water Sprout: A very vigours shoot arising out of advantages buds on main scaffold branches, on the leader or in the vicinity of large pruning wounds.