Types and applications of plant growth regulators
1. Types
1. growth promoter. It is a synthetic substance similar to auxin, gibberellin and cytokinin. It can promote cell division and elongation, the differentiation and formation of new organs, and prevent fruit from falling off. Including: 2,4--D, indole acetic acid, indole butyric acid, naphthalene acetic acid, 2,4,5--T, 2,4,5--TP, carbamazepine (carbamate), sarcine , GA3 gibberellin, kinetin, 6---BA, PBA, zeatin, etc.
2. Growth retarder. To inhibit cell division and elongation in the lower region of the stem apex, the growth rate is slowed down.
compound. It can lead to shortening of internodes in plants, induce dwarfing, and promote flowering, but has no effect on leaf size, number of leaves, number of nodes and apical dominance. Growth retardants primarily act to block gibberellin biosynthesis. These substances include: chloroquine (CCC), B, (bijiu), Amo-1618, phosphine chloride-D (foss square-D), chloroquine (regulatory safety) and the like.
3. growth inhibitor. Unlike growth retarders, it mainly inhibits cell division in the apical meristem, resulting in a loss of apical dominance, increased collaterals, and reduced leaf size. It cannot be reversed by gibberellin. Such substances are: MH (suppressing bud Dan), dikegula acid, TIBA (triiodobenzoic acid), chlormethan (plastic), glyphosate and so on.
4. Ethylene release agent. A synthetic ethylene-releasing compound that promotes fruit ripening. Ethephon is the most widely used one. Ethephon is stable when the pNet is below 4. When the pH value in the plant reaches 5~6, it slowly degrades and releases ethylene gas
5. Defoliant. Defoliants can cause the release of ethylene, which causes leaves to senesce and fall off. Its main substances are tributyl trithiobutyrate, calcium cyanamide, oxadoxol, aminotriazole and so on. Defoliants are often herbicides.
