Plant growth regulators are a class of organic substances with physiological and biological effects similar to natural plant hormones. Plant growth regulators can be synthetic chemical substances or natural plant hormones extracted from microorganisms, which can regulate the growth and development of plants. The use of plant growth regulators in agricultural production can effectively regulate the growth and development process of crops, including a series of plant life processes such as cell growth, cell division, rooting, germination, flowering, fruiting, fruit ripening, and fruit shedding. Finally, the purpose of stabilizing yield, increasing yield, improving crop quality, and enhancing crop stress resistance is achieved.
Substances with functions to regulate plant growth and development have been found to include auxin, gibberellin, ethylene, cytokinins, brassin, jasmonic acid, chlorophyll and polyamine.
Ethylene plant growth regulators not only promote fruit ripening, leaf senescence, abscission formation, and induce root occurrence, but also have a growth retarding effect. Ethylene is difficult to use in production because it is a gas. Therefore, compounds that release ethylene in plants, such as ethephon, have been synthesized. Ethephon is widely used as a plant growth regulator for vegetables, fruits and other crops. The role of ethephon includes: promoting fruit ripening; promoting plant dwarfing, preventing lodging; stimulating the germination of some plant seeds, releasing plant dormancy; inducing flowering, etc.
The most widely used plant growth regulators are the auxins. Auxins are a class of endogenous hormones containing an unsaturated aromatic ring and an acetic acid side chain. Auxins have many physiological functions, the most obvious of which is to promote growth. At the cellular and organ levels, auxins play important roles in promoting cell division and elongation, differentiation and new organ formation. At the whole plant level, auxins have roles from seed germination to fruit ripening. Auxins promote the occurrence of lateral and adventitious roots, regulate flowering and sex differentiation, regulate fruit set and fruit development, and control apical dominance.
Gibberellins are a class of diterpene acid compounds. As plant growth regulators, the role of gibberellins is to promote cell elongation and division, to promote the elongation and growth of plant stem nodes; to break the dormancy of plant organs such as seeds and tubers, and to promote the growth of seedlings; to inhibit the formation of flower buds; Grape kernels increase; increase fruit set rate; adjust fruit shape.
Cytokinin plant growth regulators can be absorbed by the germinating seeds, roots, stems and leaves of plants, and their functions include: promoting plant cell division, promoting cell expansion, promoting bud differentiation, promoting lateral bud development and eliminating apical dominance. Cytokinin plant growth regulators can delay the senescence of leaves, flowers and fruits in production practice, increase fruit set rate, improve fruit quality, and can also be used for vegetable preservation.
Although its structure is quite different from other cytokinins, forchlorfenuron has strong activity and is currently the synthetic cytokinin with the highest activity in promoting cell division.
Brassinosteroids plant growth regulators have a wide range of physiological effects and extremely high physiological activities, which can increase the resistance of plants to injury, promote nucleic acid and protein synthesis, promote cell division and elongation, increase plant growth and development speed, and increase crop yield.