Gibberellin action and method of use

As an important plant hormone, gibberellin (GA) plays an important role in regulating seed germination, leaf extension, stem and root elongation, flower and fruit development, and is used in the daily management of crops. Quite extensive.

The main role of gibberellin

Promote stem elongation

The most prominent effect of gibberellin on plants is to stimulate the elongation of the stems, so that the height of the plants is significantly increased, especially for the elongation of the stems. Gibberellin does not change the number of internodes, but has the effect of stimulating plant cell elongation and promoting cell division. Just like a giraffe's neck is very long, but its cervical vertebrae is just the same as our humans, only seven, but each piece of cervical vertebrae is particularly long.

Promote leaf growth

Gibberellin not only promotes the elongation of stems, but also promotes the growth and expansion of leaves, and even changes the shape of leaves. Gibberellin negatively regulates the complexity of leaf structure. As above, the level of gibberellin can make tomato grow only a single leaf with smooth edges; while the topping stage of tobacco leaves sprays gibberellin and its late parietal opening Have a big impact. It can promote the stretch, smoothness and wrinkles of the top tobacco leaves, and can increase the width of the top tobacco leaves and promote the increase of yield.

Improve resilience

Gibberellins are also involved in the process by which plants are resistant to many abiotic stresses. For example, under low temperature, high salt, drought and hypertonic environmental stress, plants can slow down the growth of gibberellin to adapt to the external environment; in contrast, plants can also escape the mechanism through the increase of gibberellin. Thereby getting rid of environmental stress such as flooding.

Promote germination and break sleep

The seeds of lettuce, tobacco and begonias need to be germinated in the presence of light, known as the seeds of light. Treatment of such light-demanding seeds with gibberellin can also germinate in the dark. On the contrary, for those seeds that germinate under dark conditions, after gibberellin application, they are easy to germinate under light conditions. For example, ginseng is soaked with 20ppm gibberellin for 15 minutes, and the seedlings can be emerged 2 days earlier, and the germination rate is also significantly increased.

Gibberellin has a certain effect on relieving dormancy. The main mechanism is that the gibberellin can block the degradation of intercellular filaments in the intercellular sleep release signal, so that the signal substance is transported to the apical meristem. Organize, thereby releasing sleep. From a biological point of view, after gibberellin treatment, it can activate redox metabolic enzymes, energy metabolism, etc., and release dormancy early. The most obvious example of gibberellin for releasing dormancy is breaking the dormancy of potato tubers.

Replace plants for light, low temperature, etc.

Long-day plants can only stay in vegetative growth and not turn to reproductive growth under short days of 10 to 12 hours. These long-day plants grown under short days are treated with gibberellin, and they can form stems and flowering normally.

In the first year of growth, biennial plants such as cabbage, beets, radishes and carrots need to go through a fairly long winter. After receiving enough low temperature, they can form stems and flowering in the second year after vernalization. If they are treated with gibberellin in the first year of their growth without vernalization, they can replace some of the low temperature and help the flowering and fruiting.

Relationship between gibberellin and other hormones

The interaction between gibberellin and other plant hormones determines the regulation of gibberellin on plant growth and development.

Auxin

Gibberellin and auxin play a superimposed role in regulating cell expansion and tissue differentiation, respectively. Auxin can affect both the synthesis of gibberellin and the signal transduction of gibberellin.

Cytokinin

Gibberellin and cytokinin play opposite roles in the development of plants, and there is an antagonistic effect between the two hormones. Cytokinins block the production of gibberellins and promote its degradation, while gibberellins inhibit the response of cytokinins.

Abscisic acid

Gibberellin promotes seed germination, plant flowering and fruit development, while abscisic acid inhibits these growth and development processes, and the abscisic acid content of the fruit tree in fruit setting period will cause a lot of physiological fruit drop. For example, citrus sprays gibberellin during the physiological fruit drop period, the purpose is to increase the content of gibberellin in the tree, reduce the proportion of abscisic acid, and achieve the purpose of fruit preservation.

Ethylene

Ethylene is a gas hormone related to environmental stress. There are synergistic effects and antagonism between ethylene and gibberellin at different stages of growth and development. In addition, the transformation of relationships is also closely related to environmental factors.

Gibberellin manual

Main dosage form

Common dosage forms include emulsifiable concentrates, crystalline powders, soluble tablets, soluble granules, and the like. Note that gibberellin powder is insoluble in water. When using it, first dissolve it with a small amount of alcohol or white wine, then dilute with water to the desired concentration.

How to use each crop

Lettuce: Lettuce seeds are soaked in the gibberellin solution at a concentration of 200mgL for 24 hours at 30~38°C, which can break the dormancy and germination early.

Potato: Potato diced soaked with gibberellin solution at a concentration of 0.5~2mg/L for 10~15 minutes, or soaked whole potato with gibberellin solution at a concentration of 5~15 mg/L for 30 minutes to relieve potato tuber dormancy Period, early sprouting, and urging lateral buds, the growth of young shoots is accelerated, litchi is early, and the tuber is expanded. Species with short dormancy periods use lower concentrations, while those with longer dormancy periods have higher concentrations.

Apple: spraying gibberellin solution at a concentration of 2000~4000mg/L in early spring can break the dormancy of apple buds and has a significant effect.

Strawberry: It can break the dormancy of strawberry plants, and promote cultivation and semi-promoting cultivation in strawberry greenhouses. After 3 days of heat preservation in the greenhouse, when the flower buds appear more than 30%, 5 mL of gibberellin solution is sprayed at a concentration of 5-10 mg/L per plant. The focus is on the heart leaf, which can make the top flower in advance flowering, promote growth and early maturity.

Eggplant: low concentration gibberellin solution can break the shallow dormancy of eggplant seeds, lift the germination potential and germination rate of seeds, and the best effect is to soak the gibberellin solution at 50~100mg/L for 8 hours at room temperature. For moderately dormant eggplant varieties, whether germination test or seedling is carried out, hormones must be used to break the seed dormancy treatment. It is recommended to treat the concentration at 500mg/L for 24 hours. Spraying with gibberellin solution at a concentration of 25-35 mg/L for one flowering period can control the flowering, promote fruit setting and increase yield.

Soybean: Soaking with gibberellin solution at a concentration of 3.5 mg/L can effectively accelerate the initial germination speed of spring sowing soybeans at 10-15 °C, significantly accelerate the growth rate of young roots, and increase the fresh weight and dry weight of young roots.

Sweet potato: soak the potato pieces in the concentration of 10~15mg/L gibberellin solution for 10 minutes, remove the air-dried seedlings after drying, and break the dormancy period, early emergence, save the seed, and fight for the season. .

Sorghum: Soaking seeds with gibberellin solution at a concentration of 5~10mg/L can promote germination, stimulate hypocotyl elongation and increase dry weight, and obviously emerge early.

Camellia: The gibberellin solution at a concentration of 20 mg/L can be used to soak for 4 hours to speed up the germination.

Cotton: Soaking seeds with 20mg/L gibberellin solution for 6-8 hours can reduce the low temperature and other adverse conditions, delay germination or cause rotten seeds, and promote cottonseed germination.

Grapes: 5 days before flowering to the initial flowering stage, soaking the ears with 60mg/L gibberellin can significantly increase the fruit setting rate of grapes, and use gibberellin 100~150mg/L in the flowering period from 11 to 14 days and 10 days after flowering. 100mg/L dipping the ear 2 times to prevent falling flowers and fruit.

Tomato: Spraying the gibberellin solution at a concentration of 30~35 mg/L for one flowering period can increase the fruit setting rate and prevent the empty fruit.

Citrus: Spray a 50mg/L concentration of gibberellin after the first early physiological fruit drop, or spray 50mg once before the 7th day after the flowering and after the first early physiological fruit drop to the second physiological fruit drop. /L concentration of gibberellin. During the flowering and fruiting period, the gibberellin should be combined with the appropriate watering orchard. When spraying, 0.2% urea, 0.2% phosphorus potassium source pool and 0.2% borax were added to the gibberellin solution to improve the effect of flower preservation and fruit preservation.

Kiwifruit: 2% gibberellin lanolin coated pedicel can significantly reduce the number of seeds of kiwi fruit, induce the formation of seedless fruits, and reduce the rate of fruit shedding.

Capsicum: Spraying the gibberellin solution at a concentration of 20~40mg/L for one flowering period can promote the fruit set and increase the yield.

Watermelon, melon, pumpkin, cucumber: spraying with ginseng at 20~50mg/L for 1 time, or spraying melon for 1 time at the time of melon can promote the growth and increase of production of young melon.

Rapeseed: Before the transplanting of rapeseed, the root of the gibberellin solution with a concentration of 20mg/L is used to promote the early growth of the plant and increase the yield. Spraying 25mg/L gibberellin on the leaf surface during the flowering period can increase the seed setting rate of rapeseed.

Precautions

1 can not be mixed with alkaline substances, but can be mixed with acidic, neutral fertilizers, pesticides , and mixed with urea to increase production.

2 gibberellin aqueous solution is easy to decompose, it should not be put for a long time, it should be used now. Spraying requires fine mist to spray quickly, and it should be re-sprayed within 4 hours after spraying.

3 The use of gibberellin can only exert good results under the conditions of sufficient supply of fertilizer and water, and cannot replace fertilizer.

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