Plant growth regulators are a class of substances that have similar physiological and biochemical effects to plant hormones. Plant growth regulators induce local or transient fluctuations in cellular or electrolyte exchange within plants by stimulating, inhibiting, or blocking hormone receptors, thereby increasing or decreasing a certain hormone state in plants. Plant growth regulators not only increase crop yield, but also enhance stress resistance and improve quality, playing a significant role in extending product shelf life and the development of crop breeding.1Categories of plant growth regulators
Plant growth regulators are approximately40 The active ingredient can be used as a single ingredient or in combination during use. Many plant development processes can actively regulate cultivated plants, such as accelerating or delaying seed germination, breaking plant dormancy, stimulating or reducing stem elongation, inducing flowering and fruiting, reducing or increasing fruit yield, and accelerating or delaying aging processes (including fruit ripening and leaf shedding). The benefits obtained in production include promoting crop management, increasing and ensuring the yield and quality of harvested products, and extending the storage period of crops.
According to the role of plant growth regulators in agricultural production, they can be divided into5 Class:Plant growth promoters, plant growth retardants, plant growth inhibitors, preservatives, and drought resistant agents.Usually, it can spread to the active sites within the plant body, and at very low concentrations, it can promote or inhibit certain stages of plant life processes, allowing it to function as needed.
Growth promoter:It can improve the growth efficiency of crops, transform them from vegetative growth to reproductive growth, increase fruit set rate, and achieve yield increase.
Growth retardants:The main function is to reduce the growth of new shoots, promote the formation of flower buds, improve fruit setting, delay maturation, increase hardness and storage resistance.Growth inhibitors:It can completely inhibit the growth of stem tips and has a permanent inhibitory effect on crops. Promote the transformation of crop nutritional growth to reproductive growth, reduce fruit shedding before harvest, and accelerate the maturation period.Preservatives:It has protective and therapeutic effects, inhibits the respiratory function and cell proliferation of pathogens. Mainly used for processing fruits and vegetables after harvest.Drought resistant agents:Chemical covering agents can effectively prevent the evaporation of soil moisture, increase crop root water absorption, and effectively reduce plant transpiration. Water retaining agents are mainly composed of high molecular weight water absorbing resins. Water retaining agents are mainly used in production for seed coating, transplanting plant roots, and seed and seedling preservation, allowing them to absorb moisture from the soil and air around the seeds or plants. In the early stages of drought, they can ensure the germination of seeds and the survival and growth of crops, including cuttings and transplants. Yellow humic acid is currently the main anti transpiration agent variety. Spraying it before and after crop transplantation can shorten the slow seedling stage of transplanted crops and improve survival rate.2、 Types and functions of commonly used plant growth regulatorsAuxin can promote cell division, differentiation, and growth, increase fruit setting rate, prevent fruit drop, induce the formation of adventitious roots, promote the formation and differentiation of vascular bundles in new roots, promote the growth of main roots, and improve plant germination and survival rates. Through the tender epidermis of leaves and branches, seeds enter the plant body and reach the point of action with the flow of nutrients, widely used in the rooting of tree and flower cuttings.Gibberellin has a long-lasting effect and is more efficient, stable, and safe compared to other plant growth regulators. Spraying during the seedling stage can promote root development and prevent diseases; Spraying during the growth period can promote stem and leaf growth, balance nutrition; Spraying during the flowering period can protect flowers and fruits, make them swell, have a more beautiful fruit effect, and effectively relieve crop diseases.Aminoethyl ester is a broad-spectrum plant growth regulator that can promote cell division and elongation, as well as the growth and differentiation of growth points; Increase the chlorophyll content in plants to enhance the rate of photosynthesis; Regulate the water balance within plants, enhance their absorption of water and fertilizers, in order to improve their drought resistance and cold tolerance. Promote seed germination, root development, and flower bud differentiation, promote early flowering of plants, promote early maturity of crops, increase crop yield, improve crop quality, and delay plant aging.Chlorpyriprole has the effect of affecting the development of plant buds, accelerating cell mitosis, promoting cell enlargement, differentiation, and organ formation, promoting the growth of roots, stems, leaves, and fruits, promoting crop fruiting, preventing fruit and flower shedding, accelerating leaf shedding, and delaying the aging of crop leaves in the later stage, making fruit size uniform, improving quality, and increasing yield. When the concentration is high, it can be used as a herbicide.2.5 Sodium nitrophenolateSodium nitrophenol is a broad-spectrum plant growth regulator that promotes the flow of cell protoplasts, enhances cell vitality, accelerates plant growth and development, promotes the growth of roots, stems, leaves, and fruits, preserves flowers and fruits, increases crop yield, and enhances crop stress resistance and other abilities. Low toxicity, residue free, and pollution-free, it can be used alone or as a fertilizer additive, making it an excellent fungicide, enhancer, and fertilizer.Ethylene is the simplest alkene. It exists in the plant body at a very low level and is a natural plant metabolite. It can break the dormancy of plant seeds and seedlings, induce the production of adventitious roots and root hairs, reduce plant growth rate, promote fruit ripening, promote leaf senescence, inhibit plant flowering, and can be used in plants with opposite flowers and the same plantChanging the gender and differentiation direction of flowers during early development.Cell division hormones are isolated from corn or other plants, and some are artificially synthesized. Generally produced in the roots of plants, it is a type of plant hormone that can promote cytoplasmic division and lateral elongation of cells, and can promote the differentiation and growth of various plant tissues. It has a synergistic effect with plant growth hormone. There are also effects such as relieving apical dominance, inhibiting stem elongation, inhibiting chlorophyll decomposition, breaking the dormancy of plant seeds and seedlings, promoting chloroplast development, and resisting cold.Abscisic acid, also known as abscisic acid or dormancy hormone. Named for its ability to promote leaf shedding, it is widely distributed in higher plants. In addition to promoting leaf shedding, it can also regulate the development of seeds and embryos, put buds into a dormant state, inhibit cell elongation, cause stomatal closure in plant leaves, and promote potato tuber formation. In addition, it can also increase plant stress resistance and have functions such as defending against salt damage, heat damage, and cold damage.2,4-D promotes plant growth at low concentrations, prevents flower and fruit drop, and induces parthenocarpy. Treating tomato flowers with low concentration 2,4-D aqueous solution can prevent flower and fruit drop, form seedless fruits, and promote fruit growth. High concentration 2,4-D can be used for thinning flowers and fruits, weed control, etc.2.10 Naphthalene acetic acidNaphthalene acetic acid has the effects of promoting rooting, preventing abscission, and parthenogenesis in cuttings. Soaking young green leaf cuttings in a suitable concentration of NAA solution can significantly increase rooting rate. In addition, naphthylacetic acid also has the effects of improving transplant survival rate and promoting graft healing.2.11 Plastic Surgery ElementsPlasticin is an antibiotic that can inhibit cell mitosis, suppress apical growth, promote axillary bud growth, dwarf plants, inhibit seed germination, and is also commonly used to shape dwarf tree bonsai.The product name of maleic hydrazide is Qingxian Su, which has the opposite effect to auxin. It can inhibit the germination of buds and the elongation of stems, causing plants to end their growth early, promote maturity, and prolong dormancy. Commonly used to prevent premature germination of potatoes, onions, and garlic.2.13 Dwarf growth hormoneThe effects of dwarfism and gibberellin are exactly opposite, inhibiting the elongation of various plants. Mainly used for barley, wheat, and rice to make plants shorter and stronger, and reduce lodging. Dwarfism is also used to inhibit excessive elongation of cotton branches, improve plant shape, and increase yield.The inhibitory effect of chlorfenapyr on growth is similar to that of dwarfism, but its efficacy is longer. It is used to prevent wheat lodging, inhibit excessive growth of cotton branches, and prevent shedding of buds and bells.2.15 is longer than usualThe physiological effect of aging is to weaken nutrient growth, inhibit new shoot germination, and accumulate assimilates. Beneficial for flower bud differentiation. In peanut cultivation, excessive growth often leads to lodging, resulting in reduced yield. During the peak period of stem and leaf growth, spraying the leaves with Bijiu solution can make the plant shorter and more compact, deepen the color of the leaves, thicken the leaves, and promote the transportation of more photosynthetic products to the fruiting organs below ground, thereby increasing peanut yield.Paclobutrazol is an inhibitor of GA. The main function of paclobutrazol is to dwarf plants, promote lateral growth, thicken stems, straighten leaves, increase tillering or branching, and promote early flowering and flowering period of young trees.Ethylene decomposes and releases ethylene at pH>4.1. The function of ethephon is similar to that of ethylene, as it promotes fruit ripening, induces cucumber female flower formation, and stimulates the excretion of secondary metabolites.
It is worth noting that operating according to the dosage, period, and method indicated on the registration and approval label of plant growth regulators generally does not pose any harm to human health. However, in actual production, improper use of medication can lead to rapid growth, inhibition of growth, and even death of crops. Moreover, it can have a certain impact on the quality of agricultural products and human health.
