How to spray plant growth regulators on walnuts farming?
Walnuts,their nuts are rich in flavonoids, vitamin E and unsaturated fatty acids, which have special effects on preventing and treating thrombosis, lowering blood pressure and anti-aging. There are about 23 species of walnuts in the world. Plant growth regulators are a kind of substance similar to plant endogenous hormones, which are synthesized, extracted and fermented by microorganisms. They are mainly used to regulate plant growth, development and fruiting. Plant growth regulators are divided into three types according to their functions: growth promoters, growth retardants and growth inhibitors. This article reviews the research progress of plant growth regulators on walnuts, in order to provide a reference for the better application of plant growth retardants on walnuts.
1. Types and functions of plant growth regulators
Currently, the substances that have been found to regulate plant growth and development mainly include: Auxin, which promotes cell division and differentiation and increases fruit setting rate; Gibberellic Acid GA3, which promotes stem and leaf growth, balances nutrition, protects flowers and fruits, and makes fruits swell; ethylene, which breaks the dormancy of plant seeds and seedlings, promotes fruit ripening, and promotes leaf aging; Cytokinin, which promotes cytoplasmic division and lateral cell elongation; abscisic acid, which promotes leaf shedding and regulates the development of seeds and embryos; Brassinolide, which increases chlorophyll content, improves photosynthesis efficiency, promotes root growth, and protects flowers and fruits.
2. Application of plant growth regulators in walnuts
1. Controlling tree vegetative growth
The vegetative growth of fruit trees is mainly manifested in the growth of roots, stems, and leaves. Proper control of vegetative growth can significantly promote reproductive growth. Studies have shown that for trees with vigorous bodies and fewer female flowers, 15% Paclobutrazol wettable powder can be applied to the soil in April or autumn, with a dosage of 2g-3g per 1m², or 15% Paclobutrazol 150 times solution can be sprayed on the leaves twice, both of which have a significant inhibitory effect on vegetative growth. For 4-year-old main-trunk fruiting walnuts, spraying 3000 mg.L of Paclobutrazol reduced the length of the one-year-old fruiting branches by 36.83% compared with the control. Studies have shown that spraying Chlormequat Chloride at a concentration of 3000 ppm during the walnut growth cycle reduced the total growth of walnut plant height by 17.66 cm compared with the control. Studies have shown that in the early stage of walnut new shoot growth, spraying 1500mg·L of B9 and Ethephon mixture on the walnut leaves every 15 days can significantly reduce the height and trunk circumference of young walnut trees, and promote early fruiting of young trees.
2. Regulate flower bud differentiation and development
The flower buds of fruit trees mark the transition of the tree from vegetative growth to reproductive growth. Their differentiation is affected by endogenous hormone balance, genetic material, nutrient accumulation, exogenous regulatory substances, and the sensitivity of the buds to external environmental stimuli. Studies have shown that spraying Naphthalene acetic acid + 3,6-Dihydroxypyridazine solution on young walnut leaves can increase the number of nutrient buds on short branches. The spraying of Naphthalene acetic acid and TIBA can control the number of male and female flowers and change the proportion of different buds on the treated branches.
3. Improve the fruit setting rate of walnuts and increase yield and quality
The fruit setting rate is a key factor in the formation of fruit tree yield, and plant growth retardants have a significant effect on increasing the fruit setting rate, preventing fruit drop, and improving quality. Studies have shown that spraying walnuts with Indole-3-acetic acid (IBA) at a concentration of 7 mg.L twice significantly increased the fruit setting rate by 27% compared with the control.
4. Improve the survival rate of grafting
Walnut grafting is mainly divided into bark grafting, cut grafting, belly grafting and bud grafting. The spraying of plant growth regulators can significantly improve the survival rate of scions. Studies have shown that when the grafted scions are soaked in 6-BA solution, the germination rate can reach 44.5%, which is 10.8% higher than the control. Studies have shown that the survival rate of the scion cut surface is increased by 32.3% compared with the control by immersing the scion cut surface in 250 mgL/3-indolebutyric acid (IAA) solution.
5. Promote the cracking of walnut green skin
Walnuts are harvested in batches when the green skin cracks 50%. Plant growth regulators can significantly promote the cracking of walnut green skin, which is convenient for centralized harvesting and reduces production costs. Studies have shown that about 3 weeks before walnut harvesting, spraying walnuts with a mixture of 125 mg.L of ethephon and 250 mg.L of naphthaleneacetic acid can reach 100% of the cracking rate of walnut green skin, while the leaf fall rate is only 20%. Tian Ziwu et al.'s research shows that 18 days before harvesting, 10L of ethephon 500 mg·L + Naphthalene acetic acid 1000 mg.L mixed solution was injected into 7-year-old walnuts, and the green peel cracking rate reached 83%. The green peel cracking rate was 78% after injection 6 days before harvesting.
6. Growth regulators improve walnut resistance
The degree of lignification of walnut seedlings is the key to the tree's ability to resist severe cold and drought, and is an important guarantee for the safe wintering of fruit seedlings. The application of regulators can significantly increase the degree of lignification of seedlings and improve resistance. The spraying of Paclobutrazol (Paclo) can significantly increase the carbohydrate level of walnut roots, stems, and leaves, and affect the synthesis of plant cholesterol and reduce the synthesis of saturated fatty acids, thereby affecting membrane permeability and enhancing cold resistance.
1. Types and functions of plant growth regulators
Currently, the substances that have been found to regulate plant growth and development mainly include: Auxin, which promotes cell division and differentiation and increases fruit setting rate; Gibberellic Acid GA3, which promotes stem and leaf growth, balances nutrition, protects flowers and fruits, and makes fruits swell; ethylene, which breaks the dormancy of plant seeds and seedlings, promotes fruit ripening, and promotes leaf aging; Cytokinin, which promotes cytoplasmic division and lateral cell elongation; abscisic acid, which promotes leaf shedding and regulates the development of seeds and embryos; Brassinolide, which increases chlorophyll content, improves photosynthesis efficiency, promotes root growth, and protects flowers and fruits.
2. Application of plant growth regulators in walnuts
1. Controlling tree vegetative growth
The vegetative growth of fruit trees is mainly manifested in the growth of roots, stems, and leaves. Proper control of vegetative growth can significantly promote reproductive growth. Studies have shown that for trees with vigorous bodies and fewer female flowers, 15% Paclobutrazol wettable powder can be applied to the soil in April or autumn, with a dosage of 2g-3g per 1m², or 15% Paclobutrazol 150 times solution can be sprayed on the leaves twice, both of which have a significant inhibitory effect on vegetative growth. For 4-year-old main-trunk fruiting walnuts, spraying 3000 mg.L of Paclobutrazol reduced the length of the one-year-old fruiting branches by 36.83% compared with the control. Studies have shown that spraying Chlormequat Chloride at a concentration of 3000 ppm during the walnut growth cycle reduced the total growth of walnut plant height by 17.66 cm compared with the control. Studies have shown that in the early stage of walnut new shoot growth, spraying 1500mg·L of B9 and Ethephon mixture on the walnut leaves every 15 days can significantly reduce the height and trunk circumference of young walnut trees, and promote early fruiting of young trees.
2. Regulate flower bud differentiation and development
The flower buds of fruit trees mark the transition of the tree from vegetative growth to reproductive growth. Their differentiation is affected by endogenous hormone balance, genetic material, nutrient accumulation, exogenous regulatory substances, and the sensitivity of the buds to external environmental stimuli. Studies have shown that spraying Naphthalene acetic acid + 3,6-Dihydroxypyridazine solution on young walnut leaves can increase the number of nutrient buds on short branches. The spraying of Naphthalene acetic acid and TIBA can control the number of male and female flowers and change the proportion of different buds on the treated branches.
3. Improve the fruit setting rate of walnuts and increase yield and quality
The fruit setting rate is a key factor in the formation of fruit tree yield, and plant growth retardants have a significant effect on increasing the fruit setting rate, preventing fruit drop, and improving quality. Studies have shown that spraying walnuts with Indole-3-acetic acid (IBA) at a concentration of 7 mg.L twice significantly increased the fruit setting rate by 27% compared with the control.
4. Improve the survival rate of grafting
Walnut grafting is mainly divided into bark grafting, cut grafting, belly grafting and bud grafting. The spraying of plant growth regulators can significantly improve the survival rate of scions. Studies have shown that when the grafted scions are soaked in 6-BA solution, the germination rate can reach 44.5%, which is 10.8% higher than the control. Studies have shown that the survival rate of the scion cut surface is increased by 32.3% compared with the control by immersing the scion cut surface in 250 mgL/3-indolebutyric acid (IAA) solution.
5. Promote the cracking of walnut green skin
Walnuts are harvested in batches when the green skin cracks 50%. Plant growth regulators can significantly promote the cracking of walnut green skin, which is convenient for centralized harvesting and reduces production costs. Studies have shown that about 3 weeks before walnut harvesting, spraying walnuts with a mixture of 125 mg.L of ethephon and 250 mg.L of naphthaleneacetic acid can reach 100% of the cracking rate of walnut green skin, while the leaf fall rate is only 20%. Tian Ziwu et al.'s research shows that 18 days before harvesting, 10L of ethephon 500 mg·L + Naphthalene acetic acid 1000 mg.L mixed solution was injected into 7-year-old walnuts, and the green peel cracking rate reached 83%. The green peel cracking rate was 78% after injection 6 days before harvesting.
6. Growth regulators improve walnut resistance
The degree of lignification of walnut seedlings is the key to the tree's ability to resist severe cold and drought, and is an important guarantee for the safe wintering of fruit seedlings. The application of regulators can significantly increase the degree of lignification of seedlings and improve resistance. The spraying of Paclobutrazol (Paclo) can significantly increase the carbohydrate level of walnut roots, stems, and leaves, and affect the synthesis of plant cholesterol and reduce the synthesis of saturated fatty acids, thereby affecting membrane permeability and enhancing cold resistance.
