Plant growth regulator is a kind of substance which has similar physiological and biological effects with plant hormones. Those that have been found with functions of regulating Plant Growth and development of Plant Growth Regulators mainly include auxin, gibberellin, ethylene, cytokinins, abscisic acid, br, salicylic acid, jasmonic acid and polyamine, and the first six categories have been applied in the agricultural production.



For the target plant, through the nutrient detection process, results can be found that plant growth regulator is exogenous of nonnutritive chemicals, usually in the plant body parts to effect, at very low concentration could promote or inhibit some link of the process of its life, to meet the needs of human development. Each plant growth regulator has a specific purpose, and the application of technical requirements are quite strict, only under specific application conditions to produce a specific effect on the target plant. Changes in concentration tend to have the opposite effect, such as a stimulant at low concentrations and an inhibitor at high concentrations.



Auxins, as the main plant growth regulator, mainly refers to indoleacetic acid, which is an important pathogenic factor. Indoleacetic acid can be synthesized by many pathogenic fungi and bacteria. Some pathogenic bacteria themselves do not produce indoleacetic acid, but because the indoleacetic acid oxidase in the body of plants is inhibited, blocked the degradation of indoleacetic acid, leading to the increase of indoleacetic acid level. Indoleacetic acid accumulation can be detected in tomato inoculated with solanella, and the content of indoleacetic acid increases continuously after inoculation for a period of time. After inoculation of tobacco with this pathogen, the indoleacetic acid content in the diseased plant increased nearly 100 times than that in the uninoculated plant.



In addition, Plant Hormone Detection found that growth Hormone may also enhance the pathogenicity of pathogens by inhibiting Plant defense response. When arabidopsis thaliana was applied to naphthalene acetic acid, the susceptibility was enhanced and the infection of pseudomonas clove increased. Suspension of auxin producing tumorigenic soil bacillus was injected into tobacco leaves, and then inoculated with pseudomonas Eugenia. As a result, the allergic reaction that should have occurred was restrained, and the degree of inhibition was related to the expression of auxin synthesis function gene of tumorigenic soil bacillus.



Cytokinins, another plant growth regulator, not only promote cell division, but also make cells larger. However, different from auxin, cytokinin increases cell volume through lateral enlargement and thickening rather than promoting longitudinal elongation of cells, which has a certain inhibitory effect on cell elongation. To eliminate apical advantage, auxin is the main cause of apical advantage, while cytokinin can eliminate apical advantage and promote the rapid growth of lateral buds. In this respect, auxin and cytokinin show obvious antagonistic effects, and the production site and operation mode of both determine the growth of roots and shoots. Cell division consists of two processes, nuclear division and cytoplasmic division. Auxin only promotes nuclear division, but has nothing to do with cytoplasmic division. Cytokinin, on the other hand, mainly ACTS on cytoplasmic division. Therefore, the effect of cytokinin promoting cell division can only be shown in the presence of auxin.



Cytokinins can also promote the biosynthesis of proteins. Because cytokinins are present on ribosomes, they encourage ribosomes to bind to mrnas to form multiple ribosomes, speeding up translation to form new proteins. It was proved that cytokinin could induce the protein synthesis of tobacco cells to form a new nitrate reductase.



Plant Growth Regulators functions and features:



(1) Plant growth regulator has a wide range of effects and many application fields. Plant growth regulator can be applied to almost includes all the higher and lower in the planting industry plants, such as field crops, vegetables, fruit trees, flowers, trees, etc., and through the regulation of plant photosynthesis, respiration, material, absorption, distribution and function, signal transduction, stomatal opening and closing, osmoregulation, transpiration processes such as regulation and control of plant growth and development, improve the relationship between plants and the environment interaction, enhance crop resilience, increase crop yield, improve quality of agricultural products, make crop agronomic traits expressed according to the demand by people in the direction of development.



(2) It can regulate both the external characters and the internal physiological processes of plants. Plant growth regulators are highly targeted and can solve some problems difficult to be solved by other means, such as the formation of seedless fruits, prevention and control of wind, control of plant shape, promotion of cuttings rooting, fruit ripening and coloring, inhibition of axillary bud growth, promotion of cotton leaf shedding.



(3) The use effect of plant growth regulator is affected by many factors and it is difficult to achieve the best. Climatic conditions, application time, dosage, application method, application site and the absorption, integration and metabolism of the crop itself will affect its effect.