Plant growth regulators have a wide range of functions and wide application fields, and the scope of application includes almost all higher and lower plants in the planting industry. Plant growth regulators can control the growth and development of plants and improve plants and the environment by regulating physiological processes such as photosynthesis, respiration, material absorption and operation mechanism, signal transduction, stomatal opening and closing, osmotic pressure regulation, and transpiration. It can enhance the stress resistance of crops, increase crop yield, and improve the quality of agricultural products; it can regulate the external traits and internal physiological processes of plants in both directions. The characteristics of its use are: small dosage, fast speed and high efficiency. Most crops only need to be sprayed once in a certain period of time in a season, and it is highly targeted and professional, and can solve some problems that are difficult to solve by other means, such as the formation of Seedless fruit.
The use of plant growth regulators
(1) Spraying method
Spraying method is one of the most commonly used methods of plant growth regulators, mainly spraying leaves, fruits or whole plants. Most plant growth regulators have the function of systemic absorption and conduction. When applying, they should be formulated into corresponding concentrations according to needs. When spraying, the droplets should be small and uniform, and the spraying site should be wet. At the same time, in order to make the agent easily adhere to the surface of the plant, an appropriate amount of surfactant can be added to it, such as washing powder, sodium dodecylbenzenesulfonate or other auxiliary agents, so as to improve the adhesion of the agent.
(2) Seed soaking method
Soak the seeds (roots and tubers) in a certain concentration of liquid medicine, and after a certain period of time, take them out and dry them for sowing. This method is called seed soaking method. In order to improve the germination rate of rice and wheat seeds, cytokinin (CTK) seed soaking can be used; gibberellin (GA) seed soaking can break the dormancy of potatoes. The type, concentration and soaking time of plant growth regulators selected for seed soaking should be determined according to the variety of plants, the purpose of seed soaking and the temperature at that time. When the temperature is high (>25°C), the time should be short, while the temperature is low (10-20°C), the time can be slightly longer. Generally, the soaking time should not exceed 24 hours, and the seed soaking time should be limited to immersing the seeds in the liquid medicine, and pay attention to the change of water quality.
(3) Seed dressing and seed coating method
Seed dressing and seed coating method are mainly used for seed treatment. Seed dressing is the addition of plant growth regulators when seeds are treated with fungicides, insecticides or micro-fertilizers. For example, dressing with diethyl aminoethyl hexanoate can stimulate seed germination and promote rooting. The seed coating method is to wrap the special seed coating agent on the outside of the seeds to form a film with a certain thickness, which can not only promote the germination of the seeds, but also achieve the purpose of preventing and controlling diseases and insect pests, increasing mineral nutrition and regulating plant growth.
(4) Dipping method
In order to make the cuttings survive and improve the survival rate, the cuttings are dipped in the liquid medicine or the base end of the cuttings is dipped in powder, and then the cuttings are placed on the seedbed. Generally, there are the following 3 methods.
①Quick dip method.
Immerse the cuttings in the high-concentration conditioner for 2 to 5 seconds, then insert them into the seedbed. The principle of this method is that high concentrations of growth regulators enter the plant tissue through the incision, thereby promoting callus formation and rooting. For example, put the base of cuttings such as grapes and kiwi fruit in 5000mg/kg indole acetic acid (IAA) solution for 3 to 5s, and then insert them in the seedbed after the base of the cuttings is slightly dry.
② slow soaking method.
Dip the cuttings in a lower concentration of growth regulator for an extended period of time to encourage rooting of the cuttings. For example, dilute naphthalene acetic acid to 20mg/kg, and then immerse the base of the cutting about 3cm in the liquid for 5 to 24 hours. The length of soaking time depends on the type of seedlings, the degree of lignification of cuttings and the difficulty of rooting. Generally, for annual cuttings, and it is difficult to grow roots, the soaking time should be longer.
③ dip powder method.
After soaking the base of the cutting with water, soak the rooting powder mixed with auxins such as IAA, α-naphthaleneacetic acid, 2,4-D, etc., and insert it into the seedbed for cultivation. This method is suitable for young branch cuttings, and the method is simple, the incision is not easy to rot, and the survival rate of hair roots is high.
(5) Irrigation method
The growth regulator is formulated into an aqueous solution, which is directly irrigated in the soil or mixed with fertilizers. For potted flowers, the amount of solution required depends on the size of the plant and the pot. Generally, a pot with a diameter of 9 to 12 cm needs 200 to 300 mL. In order to promote the flowering of the plants and control the elongation and growth of the stems and branches of the plants, it can be irrigated with a 0.1% aqueous solution of chlorophyll.
(6) The wiping method
Refers to smearing the plant growth regulator on a certain part of the crop. Apply the ointment containing the medicinal agent directly to the treatment area, mostly on the wound, which is conducive to rooting and wound healing. The high-resistance strip incision smearing method can be used for the propagation of precious and difficult-to-root flowers. The method is to first cut the phloem on the branches, apply the ointment containing the medicine to the incision, wrap a layer of moist fine soil, and wrap the outside with a film , to prevent water evaporation. It can also be applied to the buds.
(7) Bottom application method
When crops are applied with base fertilizer, some plant growth regulators can be added to them to promote the rooting and germination of crops and the absorption and utilization of fertilizers, so as to improve the resistance to stress.
(8) Drip method
In afforestation and garden work, nutrients such as plant growth regulators and micro-fertilizers are applied to trees by drip method. This method is simple to apply, easy to operate, saves cost, and can improve the utilization rate of nutrients.
(9) Root zone application method
The prepared plant growth regulator is directly applied around the root zone of the crop, absorbed by the root of the crop and transmitted to the whole plant to achieve the purpose of regulation. For example, pears, peaches, grapes and other fruit trees adopt the form of surrounding grooves, unilateral grooves, etc., and apply paclobutrazol to the root zone, which is convenient for root absorption and can control the leggy branches for a long time. The application method is simple, saves the medicine, and has stable effect, but the dosage must be strictly controlled.
(10) Fumigation method
The plant growth regulator is formulated into a volatile ester compound and vaporized to achieve the purpose of inhibiting or accelerating ripening. For example, using methyl naphthalene acetate mixed with stored potatoes can prevent potato germination during storage; using ethylene (or ethephon) to ripen bananas can accelerate the deastringency of bananas and make them easy to eat.
