Plant growth regulators are a class of substances used to regulate plant growth and development. They can be naturally occurring plant hormones or artificially synthesized similar substances. These regulators are widely used in agricultural production and can promote plant growth, increase yield and quality, and enhance stress resistance. The following are some commonly used plant growth regulators and their effects:
- Antinexapac-ethyl, a cyclohexanecarboxylic acid plant growth regulator, is an inhibitor of gibberellin biosynthesis. It controls crop vigor by reducing gibberellin content and internode elongation. This regulator can be quickly absorbed by plant stems and leaves, but less by roots. Note that antinexapac-ethyl emulsifiable concentrate should not be used on crops affected by adverse climate (such as drought, hail) or severely damaged by pests and diseases.
- Parachlorophenoxyacetic acid is a phenoxy plant growth regulator with auxin activity, and its biological activity lasts for a long time. Its physiological effects are similar to those of endogenous auxins, including stimulating cell division and tissue differentiation, stimulating ovary expansion, inducing parthenocarpy to form seedless fruits, promoting fruit setting and fruit expansion, preventing flower and fruit drop, promoting early fruit development and maturity, increasing yield and improving quality. In addition, it can effectively increase sugar content, reduce the occurrence of deformed fruits, cracked fruits, hollow fruits and fruit diseases, and is not easy to cause phytotoxicity. At high doses, 4-chlorophenoxyacetic acid also has a weed-killing effect. When spraying, make sure to spray on the pedicels and young fruits of the crop, and avoid spraying on the growing points and tender leaves. If you accidentally spray on tender leaves and cause severe leaf curling, you can spray 1 gram of 90% gibberellin with 45 kilograms of water, and the symptoms will improve after a few days.
- Chloroformamide is a broad-spectrum, multi-purpose substituted urea plant growth regulator with the effect of furfural aminopurine. Its activity in promoting cell division is about 10 times that of benzylaminopurine. The main physiological effects include promoting cell division and increasing the number of cells, thereby increasing the size of the fruit; promoting tissue differentiation and development; breaking the dormancy of lateral buds and promoting germination; delaying aging and regulating the distribution of nutrients; improving pollen fertility, inducing parthenocarpy in some fruit trees, promoting fruit setting and improving fruit quality.
- S-inducing factor, that is, natural abscisic acid, can significantly improve the growth quality of crops. It can induce and activate more than 150 genes in plants, participate in regulating growth balance and nutrient synthesis, enhance the resistance of crops to drought, low temperature, salinity, and waterlogging, effectively prevent diseases and insect pests, eliminate pesticide and fertilizer damage, protect flowers and fruits, and promote fruit expansion and early maturity. It can also enhance crop photosynthesis, promote the synthesis of amino acids, vitamins and proteins, accelerate the accumulation of nutrients, and is particularly effective in improving quality and increasing yield. After application, the seedlings have rapid and abundant rooting, and they return to green quickly after transplanting, with a high survival rate. The crops grow vigorously throughout the growth period, have strong stress resistance, and have few diseases and insect pests.
- Triacontanol is a natural long-chain plant growth regulator, which is widely found in beeswax and plant waxes. It has a wide range of physiological effects, including promoting energy storage, increasing dry matter accumulation, improving cell permeability, regulating physiological functions, increasing leaf area, promoting tissue water absorption, increasing chlorophyll content and enzyme activity, enhancing respiration, promoting mineral element absorption, and increasing protein content. It can promote crop rooting, germination, flowering, stem and leaf growth, early maturity and increase fruiting rate. When used during the crop growth period, it can increase seed germination rate, improve seedling quality, and increase effective tillering; when used in the middle and late stages of crop growth, it can increase buds, fruit setting rate (fruiting rate) and thousand-grain weight, thereby increasing yield.
- Thidiazuron is a highly effective defoliant, which can promote the natural formation of separation tissue between petioles and stems, thereby achieving shedding. It has a strong cell division-promoting effect, which can not only make cotton bolls early mature and crack, making them easy to pick, but also increase cotton yield by 10% to 20%. At high concentrations, thiadiazole can be used as a defoliant to stimulate ethylene formation, promote the increase of pectin and the enhancement of cellulase activity, accelerate the shedding of mature leaves and the opening of cotton bolls. At low concentrations, it can play a role in fruit swelling, induce plant cell division, and promote callus differentiation and budding, so it can also be used as a fruit setting agent.
- Ethephon is a growth regulator that promotes plant maturation. It is easily absorbed by plants and releases ethylene under slightly acidic conditions of plant cell fluid. It participates in almost every physiological process of plants. Its main functions include promoting fruit maturation, leaf and fruit shedding, female flower development, inducing male sterility, breaking seed dormancy, reducing apical dominance, increasing effective tillering, and making plants short and strong. When using ethephon, choose a sunny day to ensure that there is no rain within 4 to 5 hours after application to maintain the efficacy. The optimal application temperature is 16 to 32°C. When the temperature is below 20°C, the concentration should be appropriately increased. Ethephon should be harvested in time after use to avoid over-ripening of the fruit.
- Brassinolide is a steroidal compound with high biological activity in plants. Its treatment concentration is extremely low, generally within the range of 10^-5 to 10^-1 mg/kg. It can promote the vegetative growth of crops, increase the harvest of vegetative bodies, promote cell division and reproductive growth, increase the fruit setting rate, promote fruit hypertrophy, and increase the thousand-grain weight. Brassinolide has excellent performance in increasing yield, resisting stress, eliminating pesticide damage, and reducing pesticide residues.
