Auxin:
It can promote cell division and elongation, promote rooting, delay the formation of abscission layer of leaves, flowers and fruits, and promote parthenocarpy and xylem cell differentiation.
1. indoleacetic acid (IAA):
It is a natural auxin and a nitrogen-containing organic acid. Mainly distributed in the tender parts such as root tips, stem tips and flowers. It can stimulate cell expansion and elongation. The use effect is not as good as that of indolebutyric acid and naphthylacetic acid, which is unstable in plants, easy to decompose and destroyed by strong light. The concentration range of promoting growth is 1 ~ 100 mg/kg.
2. Indole butyric acid (IBA):
It is a synthetic auxin, which has good use effect, is not easy to be oxidized by the enzyme system that destroys indoleacetic acid, is not easy to conduct, is easy to remain in the treatment site, and can effectively promote the cell division of the cambium.
3. Naphthylacetic acid (NAA):
It is a white crystal and is a widely used plant growth regulator at present. But if the concentration is too high, it is easy to harm plants. It is much safer if ammonium naphthylacetate is used. When the concentration is appropriate, the effect is similar to that of indolebutyric acid, and the cost is lower.
4.2，4-D:
Pure product is white crystal, insoluble in water, so it is processed into sodium salt, amine salt or butyl ester. This is easy to do. When the concentration is slightly higher, it will inhibit the development of branches, and when it is lower than 100 mg/kg, it will stimulate the growth of plants.
(2) Gibberellin (GA):
It is a natural plant hormone, which can promote cell elongation, so it can significantly promote the growth of vegetative organs in stems and leaves. The dose is 0.0 1 ~ 0.05 mg/kg. Gibberellin can replace the low temperature and long sunshine conditions required by some plants, promote the formation of flower buds, promote flowering, and even change the color and shape of flowers. It can also make citrus, grapes and other parthenocarpy and prevent plant organs from falling off.
(3) cytokinin (CK):
Cytokinin, which exists in coconut juice, can promote cell division and expansion, promote cell division of non-meristem, prevent organ aging, promote seed germination, break dormancy, promote parthenocarpy and fruit growth, and also play a role in the occurrence and growth of roots and stems.
(4) Ethylene:
It can promote fruit ripening, inhibit stem, bud and root growth and cell elongation, promote cell expansion and organ shedding, and promote flower bud formation and lateral bud germination.
(5) Growth inhibitory substances:
It can slow down the cell division and elongation of stems or branches, and inhibit the prolonged growth of plants and branches.
Also known as Bijiu, B and Aral. Has the functions of inhibiting growth, promoting flower bud differentiation, improving cold resistance and reducing physiological diseases.
2. Chlormequat chloride:
Also known as Sanxi and chlorocholine chloride, the pure product is white crystal and easily soluble in water. It is a synthetic growth retardant. Its function is just the opposite of gibberellin, which can inhibit growth, promote flower bud differentiation, improve cold resistance and inhibit gibberellin synthesis in plants, but does not inhibit cell division, making plants shorter, stems thicker, internodes shorter and leaves dark green.
3. abscisic acid (ABA):
There is a powerful natural inhibitor in plants, which is widely distributed in young and old organs and tissues of plants, and the content is higher in the tissues that are about to fall off and sleep. It has antagonistic effect on auxin, gibberellin and cytokinin, so it can be eliminated by auxin and gibberellin. Abscisic acid can inhibit germination and branching growth, end growth ahead of schedule, increase cold resistance and prolong seed dormancy.
4. Leisure element (MH):
Also known as Ya Dan. Pure product is white crystal, slightly soluble in water, and its potassium, sodium and ammonium salts are easily soluble in water. It has the functions of inhibiting cell division and elongation, inhibiting branch growth, ending growth early, promoting branch maturity and improving cold resistance.
5. plasticine:
Also known as morphogenesis. It can inhibit growth, especially germination, dwarf plants, destroy apical dominance, promote flower bud differentiation, promote abscission formation and inhibit gibberellin synthesis in vivo.