The synthesis and application of plant growth regulators have great influence on agricultural production. In all crops, vegetable crops are the most widely used hormones, such as hormones to promote growth and development, flowering and fruit, inhibit the germination of buds, break dormancy, inhibit respiration, delay aging, storage and preservation.
First, the growth regulator is used in the tomato seedling stage
Cultivating healthy tomato seedlings is the basic guarantee of good harvest. The growing period of overwinter stubble, over summer and late autumn stubble is in high temperature and multi-seasons, especially in large seedling factories, which need to cultivate more seedlings in limited land space, and the seedlings are easy to grow, so there are more hormones used to help strengthen and dwarf. The following growth retardants can be used for tomato seedling.
Tomato seedling stage
(1) Triiodobenzoic acid (TIBA)
Antibiotic growth regulator, its physiological effect is to inhibit the transport of auxin, gibberellin, thus inhibiting cell division and differentiation, so that the plant performance dwarfism, stem thickening, loss of apex dominance, side bud sprouting, and has the effect of flower preservation and fruit preservation.
(2) Shortener and shortener
The chemical name of dwarf hormone (CCC) is 2-chloroethyl trimethyl ammonium chloride, and the chemical name of dwarf hormone is 2-chloroallyl ammonium chloride. Main physiological effects: inhibit apical dominance, inhibit barren growth, make the stalk thick, leaves thick, leaf color deepened, roots developed, resistance enhanced, fruit setting ability improved. Tomato seedling stage is more used.
(3) Polybulobuzole (PP333)
White powder, insoluble in water but soluble in methanol, diluted with methanol solution into water. Main physiological effects: inhibit gibberellin synthesis, prevent cell division and elongation. Polybulobuzole is easily absorbed by stems and leaves and conducted through xylem, which inhibits plant growth. Tomato seedling stage is more used.
Second, the growth regulator is used in the tomato fruit setting period
During the flowering and fruiting period, tomatoes are prone to fall fruit when they encounter unfavourable weather conditions such as high temperature, low temperature and cloudy days. The correct use of auxin regulators to treat flowers can effectively prevent falling flowers and fruits and ensure the formation of yield. The following auxins can be used in tomato fruit setting period.
(1) 2,4-D
2, 4-dichlorophenoxyacetic acid abbreviation, the product is 2,4-D sodium salt, soluble in water, convenient preparation. The concentration of 20 to 30mg/kg can prevent the fruit from falling off and induce the tomato to produce seedless fruit, and promote the fruit expansion, especially at temperatures below 15℃ and above 28℃. The amount of 2,4-D sodium salt is small, the effect is large, the effect is fast, but the concentration is difficult to master, easy to produce deformed fruit, sensitive to environmental temperature changes. Therefore, when the tomato is used, the concentration must be controlled, the concentration should be reduced when the temperature rises, and the concentration can be increased when the temperature decreases. At the same time, pay attention to the use of the tomato plant can not fall on the growing point and young leaves, so as not to cause hormone harm. Used in some tomato producing areas.
(2) P-chlorophenoxyacetic acid (PCPA)
The products are known as rosinol and tomalin. It can be dissolved in warm water or alcohol or dilute alkali and then formulated to a usable concentration. Compared with 2,4-D, psin is safer and less likely to produce deformed fruit, but its effect is slower. The use of concentration is generally 20 to 40mg/kg, the concentration is too low, the effect is not significant, too high prone to deformed fruit, hollow fruit. The concentration should also change with the change of external temperature, in general, the low concentration limit is taken at high temperature, and the high concentration limit is taken at low temperature.
Best when the top of the flower is yellow, not fully open, or the flower is trumpet shaped. However, it is generally believed that it is effective from 3 days before flowering to 2 days after flowering, and it is easy to cause rotten flowers when applied too early, and does not work when the flowers are lantern shaped too late. It is usually better to dip flowers in the afternoon on sunny days, and the concentration of the liquid changes in the morning because of dew on the surface of the flower handle. It is easy to cause drug damage, and it is best to carry out a dipping flower test before application: select a few normal flowers, and if the ovary of the dipped flower begins to swell within 4 to 5 days, it indicates that the concentration is appropriate, and this concentration can be applied. Premature expansion indicates that the concentration is too large, and late expansion indicates that the concentration is too small. Tomato fruit stage more application.
Third, the use of growth regulators in tomato postharvest treatment period
In order to promote the early market of tomato fruits, ethylene is often used to accelerate the ripening of immature tomato fruits in late autumn and autumn and winter cultivation. Ethylene is a gas, and the commodity used in agricultural production is 40% ethylene water agent (2-chloro-ethylphosphoric acid), which is a ripening agent. Ethylene enters the plant body, decompresses and releases ethylene, promoting fruit ripening. Its main use in tomatoes is to promote fruit ripening.
（1）Ethephon water
Three methods of application can be used: peduncle coating, fruit coating and fruit dipping:
① Peduncle coating: Tomato fruit in the white ripening stage, with 300mg/kg of ethephon on the peduncle can be.
② Fruit coating: Use 400mg/kg of ethephon to apply on the sepals of white ripe fruit flowers and their adjacent fruit surfaces.
③ Fruit extraction: After harvesting during the color transformation period, soak in 200mg/kg ethephon solution for 1min, and then extract at 25℃ to promote red.
Matters needing attention
It is prohibited to mix with alkaline pesticides and can not be diluted with alkaline water.
② When the temperature is above 20 ° C on sunny days, it should be sprayed after 6h of rain.
③ Ethethylene has a strong irritating effect on the eyes and skin, has a corrosive effect on metal utensils, and will release flammable gas ethylene when heated or met with alkali, which should be carefully stored and used to avoid danger.
Attention to the application of growth regulators
(1) Preparation principle of growth regulator stock solution
At present, most of the growth regulators on the market have been prepared with different concentrations of stock liquid, and can be used in accordance with the instructions. However, for the original powder, it is necessary to prepare the original solution before use, and then dilute it with water. First choose the solvent that can dissolve the original powder, accurately weigh it and dissolve in a small amount of solvent, and then add the solvent and water to the required amount after completely dissolving. When using, add water again and dilute to the used concentration. The purpose of the two-water dilution method is to accurately prepare the required concentration, and the stock solution is easy to preserve.
Usually, the concentration of growth regulators is very low, and it is difficult to accurately prepare the solution of the concentration of use at one time without the stock solution, so the use of the stock solution after dilution in production is the most accurate and convenient. Growth regulator stock solution must be prepared accurately. Drug weighing, solvent, solution measurement must be accurate, absolutely can not be negligent. Because the high concentration and low concentration of the same growth regulator are completely different, there are many harms caused by improper preparation of concentration in production, resulting in irreparable losses. Some growth regulators can not be directly dissolved in water, must be dissolved with organic solvents or acid-base solutions, and then diluted with water, so be sure to read the instructions carefully before preparation
(2) Precautions for the preparation of growth regulators
① Utensils and water should be clean
When preparing growth regulators do not use metal containers, ceramic or glass utensils should be used. The container and water used must be clean, otherwise it will affect the effect of the use of growth regulators.
② With the use
The original powder and liquid are stored for a long time, and once diluted to the use concentration, they are easy to deteriorate and fail under normal temperature conditions.
(3) Problems to be noted in the use of growth regulators
① The concentration should be accurate and the dosage should be appropriate
The physiological activity of growth regulators is very strong, and the physiological effects are different with different concentrations, so the concentration and dosage cannot be increased or decreased at will. For example, when tomato seedbeds use stunting growth hormone, if the concentration is too large or repeated spraying, it will harm the differentiation of tomato flower buds in the early stage, resulting in deformed flowers, deformed fruits, cracked fruits, and affect the early yield. In addition, before using the new growth regulator in a large area, it should be tested and applied first.
② Application location and time should be appropriate
The same kind of growth regulator in the same plant in different parts, or the same kind of growth regulator in different periods of use, its physiological effects are different. If 2,4-D is used for tomato dipping flowers, its role is to preserve flowers and fruits, if it drops to the leaves or growth points, it will make the leaves deformed and distorted, affecting leaf photosynthesis.
③ After the use of regulators, other cultivation management measures must be strengthened
The main function of growth regulators is to stimulate growth and regulate the distribution ratio of substances in various parts of the plant, without increasing assimilation products and manufacturing nutrients. Therefore, it must be used in conjunction with other agricultural operation techniques to achieve the intended purpose. For example, after using 2,4-D or anticlotin to protect the tomato flower and fruit, if the pruning is not timely, the plant branches and leaves grow excessively, the fruits and flowers do not get enough nutrients, it will cause the fall of flowers and fruits, the fruit expansion rate slows down, growth stagnation and other adverse consequences. Moreover, after the use of growth regulators, if the tomato plants in the field do not get enough fertilizer water, the seedlings are weak, the growth is short, the nutrition is insufficient, and the increase effect of the flower and fruit can not be achieved.
Sum up
From the above introduction, it can be seen that the important impact of plant growth regulators on crops, in today's highly developed agricultural planting technology, the impact of science and technology on agriculture can not be ignored, reasonable and safe use of plant growth regulators, can make farmers yield and increase income.