The difference between plant hormones and plant growth regulators

Plant growth substances include two major categories: one is produced during the plant’s own metabolism, called Plant hormones. The second is artificially synthesized organic substances with plant hormone activity, called plant growth regulators.

1. Plant hormones

Plant hormones are a type of active substances produced by plants themselves, which can regulate and control the growth, development and differentiation process of plants. These plant hormones include auxins, cytokinins, gibberellins, abscisic acid, ethylene, brassinosteroids, jasmonic acid, salicylic acid, and strigolactones. They can be transported from the site or tissue where they are produced to other organs to perform their biological functions.

Plant hormones have the following four main characteristics:

1. They are endogenous substances produced by the plant’s own metabolism, also known as endogenous hormones.
2. They are mobile and can be transferred to other parts of the plant after production to exert their regulatory effects. The speed and manner in which different plant hormones move vary depending on their species and the characteristics of the plant organ.
3. Phytohormones have regulatory effects and control the growth and development of plants by regulating their own concentration. Phytohormones can regulate plants through positive and negative feedback mechanisms. For example, high concentrations of auxin inhibit the growth of lateral buds, while low concentrations of auxin promote the growth of terminal buds.
4. Although the content of plant hormones in plants is very low, usually measured in nanograms and micrograms, they can significantly increase their effectiveness.

Plant hormones have a variety of biological functions:

1. Participate in the regulation of plant growth and development, including cell division and elongation, tissue and organ differentiation, flowering and fruiting, maturity and senescence, dormancy and germination and other processes.
2. Participate in plant responses to abiotic stress. Regulation of environmental conditions such as drought, high temperature, salinity, mineral elements and frost.
3. Participate in plant defense against biological stress. For example, against attacks by herbivores and pathogenic microorganisms. Jasmonic acid is one of the important defense hormones, which is particularly important for plants to resist herbivorous insects and necrotrophic pathogenic bacteria. Salicylic acid plays a key role in plants’ resistance to living and semi-living pathogenic microorganisms.

2. Plant growth regulators

Plant growth regulators are a class of chemicals that regulate plant growth and development. They can promote plant growth, inhibit plant growth, delay plant growth, delay plant aging and preserve plants, etc.

PGR divided into five categories according to their functions: growth promoters, growth inhibitors, growth retardants, preservatives and drought-resistant agents.

1. Growth promoters can promote the growth and development of plants. Common ones include naphthylacetic acid, 2,4-dichlorophenoxyacetic acid, chlorfenuron, ethephon, etc.
2. Growth inhibitors mainly inhibit the synthesis of auxin and the growth of apical meristems. Common ones include triiodobenzoic acid, plasticine, cyanine, etc.
3. Growth retardants mainly inhibit the biosynthesis of gibberellins and the growth of sub-apical meristems. Common ones include chlormequat, paclobutrazol, Biju, mesoquat, etc.
4. Preservatives can inhibit the respiration and metabolism of plants, reduce the activity of enzymes, control the growth and reproduction of diseases and spoilage-causing bacteria, and keep fruits and vegetables fresh. Common ones include thiabendazole, fentanyl, etc.
5. Drought-resistant agents can enhance the drought-resistant ability of crops by reducing stomatal opening, inhibiting transpiration, increasing chlorophyll content, and improving root activity. Commonly used ones include fulvic acid, 2-(acetoxy) benzoic acid, etc.

There are some differences between plant growth regulators and plant hormones.

1. Plant hormones are hormones synthesized by plants themselves, while plant growth regulators are chemicals that are artificially synthesized or extracted from microorganisms.
2. There are relatively many types of plant hormones, including hormones synthesized by plants themselves, such as gibberellins, auxins, abscisic acid, etc., while there are relatively few types of plant growth regulators.
3. phytohormones exist stably in plants, while plant growth regulators need to be artificially applied in agricultural production. In addition, there are some differences in the use and application of phytohormones and plant growth regulators. Phytohormones are generally used to regulate the growth and development of plants and enhance plant stress resistance, while plant growth regulators are more used in agriculture. In production, such as promoting crop growth and controlling crop growth.

In short, plant growth regulators are a class of chemicals that are artificially synthesized or extracted from microorganisms. Correspondingly, phytohormones are hormones synthesized by plants themselves. There are certain differences in their sources, types, stability and applications. The rational application of plant growth regulators can better promote crop growth, regulate plant physiological processes, etc. Thereby can improve agricultural production efficiency.