Gibberellin is a ubiquitous plant hormone and derived from a tetracyclic skeleton. Its chemical structure belongs to diterpenoids. It can stimulate leaf and bud growth. There are at least 38 known gibberellins. Gibberellin is used in agricultural production and shows better results in some aspects. For example, it can increase the yield of seedless grapes and break the dormancy of potatoes; when brewing beer, GA3 can be used to promote the germination of barley seeds for maltose preparation; in hybrid rice seed production, the flowering period is adjusted so that parents can meet the flowering period and so on.

Gibberellin is widely distributed in quilts, gymnosperms, ferns, brown algae, green algae, fungi and bacteria, and it is mostly found in vigorous growth parts, such as stem ends, young leaves, root tips and fruit seeds.

The main functions of gibberellin

1. Promote the growth of stem

The most prominent effect of gibberellin on plants is to stimulate the elongation of the stem, which significantly increases the height of the plant, especially the elongation of the flower stem. Gibberellin does not change the number of internodes, but has the effect of stimulating plant cell elongation and promoting cell division.

2. Promote the growth of leaf

Gibberellin can not only promote stem elongation, but also promote leaf growth and expansion, and even change leaf shape. Gibberellin negatively regulates the complexity of leaf structure, such as increasing the gibberellin level so that tomatoes can only grow a single leaf with a smooth edge; while gibberellin is sprayed in the topping stage of the tobacco leaf, it has a greater impact on parietal leaf. It can promote the top tobacco leaf to stretch, smooth, reduce wrinkles, and can increase the width of the top tobacco leaf, and promote the improvement of yield.

3. Improve plant resistance

Gibberellin is also involved in the process of plant tolerance. For example, under the environmental stresses of low temperature, high salt, drought, and hyperosmosis, plants can reduce the growth of gibberellin to adapt to the external environment; on the contrary, plants also generate escape mechanisms through the increase of gibberellin in order to get rid of environmental stress such as flooding.

4. Promote germination and break dormancy

The seeds of lettuce, tobacco and begonia need to be germinated under the condition of light, which are called light-requiring seeds. When they are treated with gibberellin, those seeds will germinate in the dark. On the contrary, for those seeds that germinated in the dark, after application of gibberellin, it is easy to germinate under light conditions. For example, ginseng soaked with 20ppm gibberellin for 15 minutes can germinate 2 days earlier, and the germination rate is also significantly increased.

Gibberellin has a certain effect on the release of dormancy. From the perspective of the cellular mechanism, gibberellin can prevent the degradation of intercellular filamentin of the intercellular dormancy release signaling, so that the signaling substance is transported to the top meristem organize and thus release hibernation. From a biological point of view, after treatment with gibberellin, the redox metabolism enzymes and energy metabolism can be activated earlier, and the dormancy can be released earlier. The most obvious example of gibberellin for breaking dormancy is breaking the dormancy of potato tubers.

5. Reduce the demand for light, low temperature, etc.

Long-day plants can only stay in vegetative growth and cannot switch to reproductive growth under short-day conditions of less than 10-12 hours. With gibberellin, these long-day plants that grow under short-day light can form stems and flower and grow normally.

In the first year of growth of biennial plants such as cabbage, sugar beet, radish, and carrot, it takes a long winter, and after receiving sufficient low temperature, that is, through vernalization, the stem and flowering can not form until the second year. If they do not undergo vernalization in the first year of their growth, treatment with gibberellin can replace some of the effects of low temperature and help flowering and fruiting.

Precautions when using gibberellin

1. It 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, and it should not be left for a long time. When spraying, it is required to spray fine mist quickly, and it should be re-sprayed in case of rain within 4 hours after spraying.

3. The use of gibberellin can only play a good effect under the condition of sufficient fertilizer and water supply, and cannot replace fertilizer.