Compared with traditional agricultural technology, plant growth regulators have the advantages of low cost and high income, and their applications are increasingly widespread, especially in the cultivation of fruit trees and vegetables in facilities, in promoting the growth and development of fruit trees and vegetables, and improving the yield and quality of fruits and vegetables. It has a significant effect, and special attention should be paid to seeking the best drug type, concentration combination and timing of use during use.
(1) Choose a suitable growth regulator
Different growth regulators have different regulating effects on crops, some promote growth, some inhibit growth, and some delay growth. Therefore, the type of regulator should be selected according to the nature of the regulator and the needs of the crop. For example, auxin can be used to accelerate growth. class, growth-controlling optional auxin. Different crops have different effects of using the same regulator. For example, using 40% ethephon 800mg/kg to spray fruit once can accelerate the ripening of green tomatoes, while spraying the whole plant at the 3-4 leaf stage of cucumber twice or 3 times for pumpkin. At the 4-leaf stage, the whole plant is sprayed with 100-200 mg/kg of 40% ethephon once, which can increase the number of female flowers of cucumber and pumpkin. For example, p-chlorophenoxyacetic acid can be safely and effectively applied to the dipping flowers of Solanaceae vegetables, but if it is sprayed on cucumbers, green peppers, and kidney beans, it will cause serious phytotoxicity to young tissues and leaves. Yunda-120 applied to food crops, if used on eggplants in small arched sheds in early spring, will cause the eggplants to grow wildly and bear small stiff fruits. Therefore, when using plant growth regulators, it should be applied according to the scope of use on the instructions, and the scope of application cannot be expanded at will.
(2) Accurate timing of application
Most of the growth regulators are plant exogenous hormones. Whether the effect of water chestnut can be fully developed is closely related to the growth period of the plant. When using it, we must seize the opportunity to achieve the desired purpose. If ethephon is used to increase the female flowers of melons, it must be sprayed at the seedling stage. If it is too late, the sex of the early flowers has been determined, and the purpose of inducing female flowers cannot be achieved. Spraying gibberellin at the flower bud differentiation stage of citrus can inhibit the formation of flower buds, but spraying gibberellin at the young fruit stage of citrus can improve the fruit set rate. The effect of using the same growth regulator in different periods of the same crop varies greatly. For example, gibberellin 500-1000mg/kg is sprayed 1-2 times at the 3-4 leaf stage of cucumber to induce female flowers, change the ratio of male and female flowers, and increase the number of female flowers. However, spraying the cucumber once at the same concentration can improve the fruit setting rate and increase the yield; and spraying the melon with gibberellin 10-50mg/kg once before harvesting can prolong the storage period. . Therefore, selecting the best timing of use according to the object of use and the purpose of use is the key to the use of plant growth regulators. In addition, the plant growth regulator is better to use before 10 am or after 4 pm on a sunny and windless day. Do not use it in rainy days. If it rains 2 hours after spraying, it should be sprayed again.
(3) Correctly grasp the concentration, dosage and administration method of the drug
Plant growth regulators will have different effects due to different concentrations. Insufficient or too high concentrations will not achieve the expected effect, and even cause serious adverse consequences. For example, when using p-chlorophenoxyacetic acid on tomato, if the concentration is too high or repeated use, it is easy to form stiff fruit, deformed fruit, hollow fruit, etc., resulting in decreased yield and quality. The use concentration should be accurately prepared according to plant species, growth period and its performance, application purpose, application frequency, environmental factors, etc. If you need to pay attention to the acidity and alkalinity of the water, so as to avoid the bad effect of the regulator. At the same time, the absorption rate of growth agent by crops is closely related to environmental conditions, especially temperature. The general rule is that plants absorb slowly at low temperature and absorb quickly at high temperature. This is the main reason why plant growth regulators are prone to phytotoxicity under high temperature. Therefore, the appropriate concentration should be selected according to the environmental conditions at the time of use. For example, when using p-chlorophenoxyacetic acid solution to protect flowers and fruits, it should be applied in winter or early spring when the temperature is low, and the concentration should be 40-50 mg/kg. 20～30mg/kg. When using plant growth retardants to inhibit plant growth, multiple applications of small doses are better than single application of large doses, which can not only maintain the inhibitory effect, but also avoid the formation of toxicity to plants, which is conducive to the absorption of the agent by plants. Broad-spectrum plant growth regulators are generally sprayed 2 to 3 times, and plant growth retarders should be sprayed in small doses for multiple times.
In addition, you should master the correct method of use, such as dipping flowers with conditioner, instead of dipping the whole flower in the conditioner liquid, smear the flower stalk with the conditioner liquid, if you don't pay attention to the use method, dip the flowers In the liquid medicine, it will produce phytotoxicity and cause the spread of Botrytis cinerea.
(4) Pay attention to the influence of environmental conditions on pesticide application
The application of plant growth regulators should be carried out within a certain temperature range, and the application concentration should be adjusted accordingly with changes in temperature. Use low doses at high temperatures and high doses at low temperatures. Otherwise, using a high dose at high temperature is prone to phytotoxicity; and using a low dose at low temperature cannot achieve the effect of increasing production. When p-chlorophenoxyacetic acid is applied to tomatoes, even under normal dosage, it is easy to produce phytotoxicity when the temperature is lower than 15°C or higher than 30°C. At low temperature, it is easy to form papillary phytotoxicity at the umbilicus of tomato, and at high temperature, it will form radial cracking phytotoxicity at the umbilicus. Generally, dipping flower and fruit-preserving regulators contain 2,4-drops and other chemical components that are easy to drift, and it is easy to drift when applied at high temperatures, causing phytotoxicity to plant leaves or adjacent sensitive crops.
In preventing tomato flower and fruit drop, 2,4-drop, tomato spirit, p-chlorophenoxyacetic acid and other regulators can be used. If high temperature or low temperature make tomato flowers and fruits drop, spraying p-chlorophenoxyacetic acid can significantly improve the fruit setting rate. When the temperature is low, the effect of 2,4-D in stimulating ovary enlargement is more obvious, so it is better to use 2,4-D when the night temperature is lower than 15℃.
(5) Care must be taken when using multiple drugs in combination
When several problems need to be solved at the same time in production, multiple drugs can be used together. Mixed use of medicaments that do not react chemically with each other can promote strengths and avoid weaknesses, and achieve twice the result with half the effort. Plant growth regulators are mixed with pesticides and fertilizers to save labor and time. For example, in order to prevent the spread of botrytis during the process of dipping and spraying flowers, add 0.1% Pythium to the solution of p-chlorophenoxyacetic acid and 2,4-drop. Lee (Skling) effect is remarkable. However, it should be noted that some medicaments cannot be mixed, and the effect of increasing or decreasing the efficacy of the mixed medicaments must be fully understood before mixing. The following situations may occur when pesticides or fertilizers are mixed.
① Synergistic effect
Generally occurs between promoting or inhibiting plant growth regulators. When mixed, the effect of one aspect is often further improved. Such as naphthalene acetic acid or indole acetic acid mixed with gibberellin can further promote the growth of crops.
② Complementary effect
If cytokinin and gibberellin are mixed at a certain concentration, the regulation effect is better and the effect time is longer.
③ Antagonism. Generally
there is antagonism between the two types of plant growth regulators of promoting type and inhibitory type, which cannot be mixed, and there must be a certain time interval when they are used separately. This effect is often used to solve practical problems in production, such as excessive application of growth inhibitors such as paclobutrazol and excessive inhibition of growth, which can be relieved by spraying 0.05% gibberellin or brassinolide solution. For the phytotoxicity of tomato leaves caused by the excessive concentration of p-chlorophenoxyacetic acid, 2,4-drop spraying and dipping flowers, it should be strictly distinguished from tomato virus disease. Plant power, Penshibao and other growth promoters can be adjusted to reduce the loss of phytotoxicity.
Therefore, before using the mixed drug in a large area, the instructions must be carefully read, or if necessary, the pre-mixed drugs and fertilizers can be tested on a small scale to determine the type, concentration and dosage form of the appropriate regulator, so as to achieve scientific and rational use. the goal of. If foaming, flocculent precipitation, stratified oil splatter, and oil beads appear, it means that they cannot be used in combination. If there is no reaction, they can be used in combination. For example, ethephon and gibberellin cannot be mixed with alkaline pesticides, and the concentration of naphthalene acetic acid should be increased when naphthalene acetic acid is mixed with Bordeaux mixture.
