The Discovery History of Gibberellin
● 1934, after Japanese plant pathologist TeijiroYabuta separated amorphous GA from the fermentation filtrate of bakanae, people began to study GA.
●1In 958, Macmillan separated GA 1 crystal from immature seeds of kidney beans, and the chemical structure of GA was gradually determined.
With the improvement of science and technology, especially the use of special analytical methods and precision instruments, it is found that GA exists not only in rice, but also in other higher and lower plants and microorganisms.
Main functions of gibberellin
Promote the elongation and growth of stems
The most prominent effect of gibberellin on plants is to stimulate the elongation of stems and obviously increase the height of plants, especially the elongation of flower stems. Gibberellin does not change the number of internodes, but it can stimulate plant cell elongation and promote cell division. Just like a giraffe's neck is very long, but its number of cervical vertebrae is the same as ours, only seven, but each cervical vertebra is particularly long.
Promote leaf growth
Gibberellin can not only promote the elongation of stems, but also promote the growth and expansion of leaves, and even change the shape of leaves. Gibberellin negatively regulates the complexity of leaf structure, such as increasing gibberellin level so that tomatoes can only grow simple leaves with smooth edges; However, spraying gibberellin at the topping stage of tobacco leaves has a great influence on the opening of the top leaves in the later stage. It can promote the spreading and flattening of top tobacco leaves, reduce wrinkles, increase the width of top tobacco leaves and promote the increase of yield.
Improve the ability to resist adversity
Gibberellin is also involved in the tolerance process of plants to many abiotic stresses. For example, under environmental stresses such as low temperature, high salt, drought and hyperosmotic, plants can slow down their growth by reducing gibberellin to adapt to the external environment; On the contrary, plants will also produce escape mechanism through the increase of gibberellin, thus getting rid of environmental stresses such as flooding.
Promote germination and break dormancy
The seeds of lettuce, tobacco and begonia need light to germinate, which is called light-needed seeds. This kind of seed that needs light can germinate in the dark if it is treated with gibberellin. On the contrary, for those seeds that germinate in the dark, it is easy to germinate under light after gibberellin is applied. For example, soaking ginseng seeds 15 minutes with 20ppm gibberellin can germinate two days earlier, and the germination rate is obviously improved.
Gibberellin has a certain effect on relieving dormancy, and the main mechanism is that gibberellin can hinder the signal transduction of relieving dormancy-the degradation of plasmodesmata callose, so that the signal substance can be transported to the apical meristem, thus relieving dormancy. From the biological point of view, gibberellin treatment can activate redox metabolizing enzymes, energy metabolism and so on in advance, and release dormancy in advance. The most obvious example of gibberellin breaking dormancy is breaking dormancy of potato tuber.
Replace the demand of plants for light, low temperature, etc.
Under the short sunshine of 10~ 12 hours, the long-day plants can only stay in the vegetative growth stage and cannot be transferred to the reproductive growth stage. Treating these long-day plants with gibberellin under short sunshine will enable them to form stems, bloom and bear fruit normally.
Biennial plants, such as Chinese cabbage, beet, radish and carrot, needs to go through a long winter in the first year of growth, accept enough low temperature, that is, vernalization, and then form stems, flowers and fruits in the second year. If gibberellin is used instead of low temperature vernalization in the first year of growth, it can replace part of low temperature and help them blossom and bear fruit.
Relationship between gibberellin and other hormones
The interaction between gibberellin and other plant hormones determines the regulation of gibberellin on plant growth and development.
plant hormone
Gibberellin and auxin play overlapping roles in regulating cell expansion and tissue differentiation respectively. Auxin can not only affect gibberellin synthesis, but also affect gibberellin signal transduction.
cytokinin
Gibberellin and cytokinin play opposite roles in plant development, and there is antagonism between the two hormones. Cytokinins hinder the production and promote the degradation of gibberellin, while gibberellin inhibits the reaction of cytokinins.
abscisic acid
Gibberellin promotes seed germination, plant flowering and fruit development, while abscisic acid inhibits these growth and development processes, and abscisic acid content in fruit trees will cause a large number of physiological fruit drops during fruit setting. For example, spraying gibberellin during the physiological fruit drop period of citrus aims to increase the gibberellin content in the tree and reduce the proportion of abscisic acid, so as to achieve the purpose of fruit protection.
ethylene
Ethylene is a kind of gas hormone related to environmental stress. At different stages of growth and development, there are both synergistic and antagonistic effects between ethylene and gibberellin. In addition, the change of relationship is also closely related to environmental factors.
Gibberellin user manual
Main dosage forms
Common dosage forms include emulsifiable concentrate, crystalline powder, soluble tablets and soluble granules. Note that gibberellin powder is insoluble in water. When it is used, it should be dissolved with a small amount of alcohol or liquor, and then diluted with water to the required concentration.
How to use each crop
Lettuce: soaking lettuce seeds in gibberellin solution with a concentration of 200mgL at a high temperature of 30~38℃ for 24 hours can successfully break dormancy and germinate early.
Potatoes: Soak potato slices 10~ 15 minutes with gibberellin solution with concentration of 0.5~2mg/L, or soak the whole potato with gibberellin solution with concentration of 5~ 15mg/L for 30 minutes, which can relieve the dormancy period of potato tubers, germinate early, push out side buds, accelerate the growth of young buds and advance. Varieties with short dormancy period use lower concentration, and varieties with long dormancy period use higher concentration.
Apple: Spraying gibberellin solution with the concentration of 2000~4000mg/L in early spring can break the dormancy of apple buds, and the effect is remarkable.
Strawberry: It can break the dormancy of strawberry plants. In the facilitated cultivation and semi-facilitated cultivation of strawberry in greenhouse, cover the greenhouse and keep the temperature for 3 days, that is, when the bud is more than 30%. Spraying 5mL gibberellin solution with a concentration of 5~ 10mg/L on each plant, especially on the heart leaves, can make the terminal inflorescence blossom ahead of time, promote growth and mature ahead of time.
Eggplant: Low concentration gibberellin solution can break the shallow dormancy of eggplant seeds and improve the germination potential and germination rate of seeds. The best effect is to soak the seeds with 50~ 100mg/L gibberellin solution at room temperature for 8 hours. For eggplant varieties with moderate dormancy, hormones must be used to break the dormancy of seeds, regardless of germination test or seedling raising. The recommended concentration is 500mg/L for 24 hours. Spraying gibberellin solution with concentration of 25 ~ 35 mg/L 1 time at flowering stage can prevent flower falling, promote fruit setting and increase yield.
Soybean: Soaking seeds with gibberellin solution with a concentration of 3.5mg/L can effectively accelerate the initial germination rate of spring-sown soybeans at 10~ 15℃, obviously accelerate the growth rate of young roots, and increase the fresh weight and dry weight of young roots.
Sweet potato: Soak potato pieces in gibberellin diluent with the concentration of 10~ 15mg/L for 10 minute, then take them out to dry, and then carry out hotbed seedling raising, which can break the dormancy period, germinate early, save seed consumption and win the season.
Sorghum: Soaking seeds with gibberellin solution with concentration of 5~ 10mg/L can promote germination, stimulate hypocotyl elongation, increase dry weight and obviously make seedlings emerge early.
Camellia oleifera: Soaking seeds with gibberellin solution of 20mg/L concentration for 4 hours can accelerate germination.
Cotton: soaking seeds in gibberellin solution with concentration of 20mg/L for 6-8 hours can reduce adversity such as low temperature, delay germination or cause rotten seeds, and promote cottonseed germination.
Grape: Soaking the ear with 60mg/L gibberellin from 5 days before flowering to early flowering can obviously improve the fruit setting rate of grapes. Full flowering period 1 1~ 14 days, full flowering period100 ~150mg/l.
Tomato: spraying gibberellin solution with concentration of 30~35mg/L 1 time at flowering stage can improve fruit setting rate and prevent empty fruit.
Citrus: spraying gibberellin with a concentration of 50mg/L once after the first early physiological fruit drop, or spraying gibberellin with a concentration of 50mg/L once 7 days after flowering, after the first early physiological fruit drop and before the second physiological fruit drop. In case of high temperature and dry weather during the flower and fruit period, the use of gibberellin should be combined with proper watering of the orchard. When spraying, adding 0.2% urea, 0.2% phosphorus and potassium source pool and 0.2% borax to gibberellin solution can improve the effect of flower and fruit protection.
Kiwifruit: 2% gibberellin lanolin coated fruit stalk can significantly reduce the number of seeds of Kiwifruit, induce the formation of seedless fruit, and reduce the rate of fruit shedding.
Pepper: spraying gibberellin solution with concentration of 20~40mg/L 1 time at flowering stage can promote fruit setting and increase yield.
Watermelon, wax gourd, pumpkin and cucumber: spraying gibberellin with concentration of 20~50mg/L for 65,438+0 times at flowering stage or 65,438+0 times at young melon stage can promote the growth and yield increase of young melon.
Rape: Before transplanting rape, dip the roots of seedlings with gibberellin solution with a concentration of 20mg/L to promote the early growth of plants and increase the yield. Spraying 25mg/L gibberellin on leaves at full flowering stage can improve the seed setting rate of rape.
Matters needing attention
① It can't be mixed with alkaline substances, but it can be mixed with acidic, neutral fertilizers and pesticides, and the yield increase effect is better when mixed with urea.
(2) Gibberellin aqueous solution is easy to decompose, so it is not suitable for long-term storage, so it should be used now. When spraying, spray fine mist quickly, and spray it again in case of rain within 4 hours after spraying.
(3) The use of gibberellin can only achieve good results under the condition of sufficient fertilizer and water supply, and cannot replace chemical fertilizer.