What plant growth regulators are needed for citrus cultivation?

Paclobutrazol

It has effects such as delaying plant growth, inhibiting stem elongation, shortening internodes, promoting plant tillering, increasing plant stress resistance, and raising yield.

Application on citrus

① It controls the sprouting of summer shoots competing for nutrients, so as to avoid causing a large amount of fruit drop, and has a fruit-retention effect.The timing of use is the summer shoot budding stage, and it can be used together with shoot-killing agents and high-potassium foliar fertilizer.

② It controls the sprouting of late autumn shoots (winter shoots) from consuming nutrients, increases the accumulation of nutrients in the plant, and has the effect of promoting flower bud differentiation.The timing of use is after the autumn shoots mature; for trees without fruit, use it together with high-phosphorus foliar fertilizer, and for trees with fruit, use it together with high-potassium foliar fertilizer.

S-abscisic acid

Also called natural abscisic acid, it can activate or induce the expression of plant resistance genes, initiate the plant's own resistance or adaptation mechanisms against adverse conditions, improve the plant's drought resistance, cold resistance, disease resistance and saline-alkali resistance, regulate plant growth, improve the quality of agricultural products, and enhance the survival ability of crops under abnormal climate and soil conditions.

Application on citrus

① It can play a role in promoting flowering and strengthening flower buds, providing a foundation for fruit retention.The timing of use is the citrus flowering stage, used together with cytokinin and boron fertilizer, etc.

② Low-concentration S-abscisic acid can dredge the veins of fruit trees and play a role in promoting budding and shoot growth.The timing of use is after the previous batch of shoots matures; it can be used with cytokinin and foliar fertilizer to promote autumn shoot growth.

③ It promotes citrus flower bud differentiation,The timing of use is after the autumn shoots mature; pay attention to the concentration used. For promoting shoots it is 4000 times, and for promoting flowers it is 2000 times.

④ Citrus awakening,The timing of use is during the period from Major Cold to Start of Spring; used together with cytokinin, Hongku and boron fertilizer, it can also increase the fruit-setting rate.

Cytokinin

It can promote cell division and regulate its differentiation, and can also delay the degradation of protein and chlorophyll, delaying senescence.

Application on citrus

① Fruit retention: cytokinin has a remarkable effect in preventing the first physiological fruit drop.The timing of use is 7 days after flower drop, and it can be used together with gibberellin.

② It promotes autumn shoot growth and can produce horizontal buds, allowing the fruiting mother branches to accumulate more nutrients.The timing of use is after the previous batch of shoots matures.

③ Citrus awakening,The timing of use is during the period from Major Cold to Start of Spring.

Gibberellin

It can accelerate cell elongation, promote cell division, and promote cell expansion. In addition, gibberellin also has physiological effects such as inhibiting ripening, lateral bud dormancy, senescence, and tuber formation.

Application on citrus

① Gibberellin has a relatively weak effect on reducing the first physiological fruit drop, but it can significantly inhibit the second physiological fruit drop.The timing of use is before the first physiological fruit cracking and before the second physiological fruit cracking; for the first time it can be used together with cytokinin.

② Reducing flower quantity,For trees that will not bear fruit next year, to reduce flower quantity, gibberellin can also be sprayed in December, once at the beginning and once at the end of the month.

Precautions for use

1

Understand the mode of action of the regulator

When using, you need to understand the characteristics of the regulator,For example, gibberellin, cytokinin, etc. have a shoot-promoting effect and also a fruit-retention effect; while paclobutrazol inhibits vegetative growth and promotes reproductive growth, etc.

They can be used in combination, but they must not be mixed at will. For example, paclobutrazol should not be mixed with gibberellin or cytokinin, so as not to affect efficacy or cause adverse effects.

2

Flexibly master the timing of use

When using regulators, they need to be used flexibly according to tree vigor, weather and other conditions, so as to achieve the best effect.For example, when autumn shoots grow to the late stage, under conditions of more rain and suitable temperature, the autumn shoots are prone to excessive vegetative growth. At this time, paclobutrazol can be sprayed earlier, with phosphorus-potassium source library added, to promote the autumn shoots to mature, fill out and thicken as soon as possible.

3

Pay attention to the concentration used

In many cases, if the concentration is not well controlled, there will be serious effects.To give a simple example, 2,4-D butyl ester: at high concentration it is a herbicide, and at low concentration it is a regulator. Another example is that when gibberellin is used to prevent young trees from flowering, the concentration is generally 100~200 ppm; if it is too high, it will cause leaves to become narrow and thin.

This article was compiled and organized by the Agricultural Assistant team. When reprinting, please be sure to indicate the source as Agricultural Assistant.