The most prominent physiological function of gibberellin is to promote stem elongation and induce short-day bolting and flowering of long-day plants. Different plants are sensitive to gibberellin. Genetic dwarf plants, such as dwarf corn and pea, are most sensitive to gibberellin, and the plant type after gibberellin treatment is similar to that of non-dwarf plants. Non-dwarf plants have only a slight reaction. Some plants are genetically short because they lack endogenous gibberellin (others are not). Gibberellin plays a regulatory role in seed germination. Starch in the seeds of many cereal plants, such as barley, is rapidly hydrolyzed during germination; If the embryo is removed, the starch will not hydrolyze. When gibberellin is used to treat non-embryonic seeds, starch can be hydrolyzed again, which proves that gibberellin can replace embryos to cause starch hydrolysis. Gibberellin can replace red light to promote the germination of lettuce seeds, and replace the vernalization of carrots. Gibberellin can also cause parthenocarpy in some plants. For some plants, especially seedless grape varieties, gibberellin treatment at flowering stage can promote the development of seedless fruits. But sometimes it can also inhibit some physiological phenomena.
Regarding the mechanism of gibberellin, the starch hydrolysis induced by gibberellin in degerminated barley seeds was deeply studied. The sterilized degerminated barley seeds were treated with gibberellin. It was found that GA3 significantly promoted the new synthesis of aleurone layer α -amylase and caused starch hydrolysis. When the whole barley seed germinates, the embryo contains gibberellin, which is secreted to aleurone layer. In addition, GA3 also stimulated aleurone layer cells to synthesize protease and promoted the secretion of ribonuclease and glucanase.
Promoting the transformation of maltose (inducing the formation of α -amylase); Promote vegetative growth (not promoting the growth of roots, but significantly promoting the growth of stems and leaves), prevent organ loss, and break dormancy.
The most prominent function of gibberellin is to accelerate the elongation of cells (gibberellin can increase the content of auxin in plants,
Auxin directly regulates cell elongation), but also promotes cell division, which can promote cell expansion (but does not cause cell wall acidification). In addition, gibberellin also has physiological effects of inhibiting maturation, lateral bud dormancy, senescence and tuber formation.