Scientific Methods for Using Fruit Tree Growth Regulators
How should growth regulators be used scientifically on fruit trees? Guidance requested. The following methods of using plant growth regulators can be used for reference: 1. Cutting rooting. Mainly used for grapes, kiwifruit, and apple dwarfing rootstocks. The commonly used agents are auxins such as indolebutyric acid (IBA), naphthaleneacetic acid (NAA), and sodium naphthaleneacetate. Methods of use: ①...
How should growth regulators be used scientifically on fruit trees? Guidance requested.
The following methods of using plant growth regulators can be used for reference:
1. Cutting rooting. Mainly used for grapes, kiwifruit, and apple dwarfing rootstocks. The commonly used agents are auxins such as indolebutyric acid (IBA), naphthaleneacetic acid (NAA), and sodium naphthaleneacetate. Methods of use:
① High-concentration rapid dipping method. Dip the base of the cuttings in a high-concentration solution (500-1000 microliters/liter) for about 5 seconds, then insert them immediately into the cutting bed.
② Low-concentration soaking method. Generally use a concentration of 50-200 microliters/liter, with a soaking time of 8-24 hours; the higher the concentration, the shorter the soaking time.
③ Powder dipping method. First dissolve the growth regulator in alcohol, then soak talc powder or clay in alcohol containing 1000-5000 microliters/liter of the active ingredient of the growth regulator; after the alcohol evaporates, a powder is obtained. Before dipping the cuttings in the powder, first soak the base in water thoroughly, and after dipping, shake off the excess powder.
2. Inhibiting new shoot growth and promoting flower bud formation. Mainly paclobutrazol.
① Scope of use. Mainly used for pome fruits, stone fruits, and citrus; the effect is obvious, as it can increase flower buds on young apple trees, lower the flowering node position of peach trees, and increase the number of flower bud nodes, but it is not obvious on grapes.
② Methods of use. Canopy spraying and soil broadcasting. Among these, soil application has a long residual effect, up to 2-3 years, requires a small dosage, and is convenient and labor-saving. In addition, trunk smearing can also be used. This method can only be used on 2-3-year-old young trees. The method is to dissolve the agent in a non-toxic organic solvent or high-concentration solution (1000 microliters/liter), then smear it on the main branches and trunk that have not yet lignified, using 0.1-0.25 grams per tree.
③ Precautions: Only vigorous trees can be treated; overly weak trees and 1-2-year-old young trees cannot be treated; it can be used continuously for at most 2 years, and if it still needs to be used, it should be discontinued for 1-2 years before resuming use; the dosage can be small but should not be excessive; orchards planted too densely should not rely on paclobutrazol. The appropriate planting distance should be determined according to the dwarfing degree of the rootstock and scion variety.
3. Young tree training and increasing branch number. ① Promoting new shoots to increase branch number. Spray synthetic cytokinin (benzyladenine) or promalin (cytokinin + gibberellin) at 150-600 microliters/liter in June-July, when new shoots are growing vigorously; secondary shoots will sprout in 5-7 days, generally 5-7 can sprout, and at most 18 secondary shoots can sprout. ② In-nursery training to cultivate large branched nursery stock. Spraying 150-600 microliters/liter benzyladenine or promalin when the seedlings reach a suitable height (when the trunk-setting height is met) can cultivate nursery stock with branches and a relatively large basal angle. ③ Making latent buds at fixed points and in fixed directions produce long branches with wide angles. During the growing season, smear an ointment prepared with benzyladenine and lanolin at 100 microliters/liter below the latent buds where branching is desired, which can promote those latent buds to sprout into buds.
4. Promoting fruit set and enlarging fruit. Treating hawthorn at the early flowering stage with 10-100 microliters/liter gibberellin can increase the fruit-setting rate. Treating Kyoho grapes, which drop fruit due to vigorous new shoot growth, can also increase the fruit-setting rate. For European pears, Jingbai pears, and Suli pears at full bloom, using 50-100 microliters/liter, 20-25 microliters/liter, and 20-25 microliters/liter gibberellin respectively can all increase the fruit-setting rate; for "Thompson Seedless" grapes, spray gibberellin at 5-20 microliters/liter at the first spraying at full bloom, then spray gibberellin at 20-40 microliters/liter 2 weeks later, and combine this with girdling of the mother branch, which doubles the berry size.
5. Preventing preharvest fruit drop. Treatment with 20-40 microliters/liter naphthaleneacetic acid and 1000-2000 microliters/liter daminozide reduces preharvest fruit drop and improves coloring.
6. Advancing or delaying fruit ripening. In the sand pear system, spray 100 microliters/liter ethephon 20-30 days before fruit ripening; for the Ussurian pear system, use 400-800 microliters/liter ethephon, with lower concentrations for weak trees and higher concentrations for vigorous trees, sprayed 135-140 days after full bloom, which can advance ripening by 14-20 days.
7. Preventing the sprouting of water sprouts from large wounds and root growth. Smearing 0.5%-1% naphthaleneacetic acid in lanolin on large pruning and sawing wounds can prevent water sprouts from sprouting and growing. For dwarfing rootstocks prone to root suckers, spraying when the root suckers have grown for 20-30 days can effectively inhibit root sucker growth.
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