Application of Plant growth regulators in Fruit production

1. Definition, types and functions of plant growth regulators 1. Definition of plant growth regulators Plant growth regulators are a class of pesticides used to regulate plant growth and development, including synthetic compounds and natural plant hormones extracted from organisms. 2. The types and effects of plant growth regulators have been found that the functional substances that regulate plant growth and development are auxin (auxin), gibberellin (GA), cytokinin (CTK), abscisic acid (ABA), ethylene (ETH) and brassinol sterol (BR), salicylic acid, jasmonic acid and polyamines. As plant growth regulators are mainly used in agricultural production in the first six categories: 2.1, the role of auxin low concentration of auxin can promote organ elongation, thus reducing transpiration water loss, more than the optimal concentration will lead to ethylene production, growth promotion will decline, or even turn to inhibition. Different organs had different responses to auxin, the root was the most sensitive, the bud was the second, and the stem was the least sensitive. Auxin (indoleacetic acid) can be synthesized artificially. Synthetic auxin-like substances such as indole propionic acid, indolebutyric acid, naphthylacetic acid, 2-methylethyl D, 4-iodophenoxyacetic acid and so on are used in production, which can be used to prevent shedding, promote parthenocarpy, thinning flowers and fruits, cutting rooting, preventing potato sprouting and so on. 2.2. The most significant effect of gibberellin is to promote plant stem and leaf elongation, promote fruit development and parthenocarpy, break the dormancy of tubers and seeds, and promote germination. Commercial gibberellins are GA3, GA4 and GA7. GA3, also known as gibberellic acid, is the earliest isolated and identified gibberellin. 2.3. The main physiological function of cytokinin is to promote cell division and prevent leaf senescence. Cytokinin can also promote bud differentiation. Synthetic cytokinins, such as 4-drop and 4-iodophenoxyacetic acid, are often used to prevent the aging of fruits and vegetables during storage. 2.4. The effect of abscisic acid is to inhibit the growth of stem and lateral buds, so it is a growth inhibitor, which is beneficial to the increase of cell volume and antagonistic to gibberellin. In production, it is used to inhibit cell division, inhibit seed germination, and promote senescence and shedding of leaves and fruits. 2.5. The main role of ethylene is to promote fruit ripening, organ shedding and senescence. Ethylene is a gas, so it is not convenient to use it in the field. Ethephon, a liquid compound that can release ethylene, has been widely used to accelerate fruit ripening, defoliation of cotton before harvest, promote boll cracking and boll opening, stimulate rubber milk secretion, dwarf rice, increase female flowers of melons and promote pineapple flowering. 2.6. Brassinol can promote cell elongation and cell division, promote vascular differentiation, promote pollen tube elongation and maintain male fertility, accelerate tissue senescence, promote horizontal root development, maintain apical dominance and promote seed germination. Other important plant growth regulators include b9, dwarf, paclobutrazol, penicillin and so on, which are mainly used for plant growth inhibition. 2. Application of plant growth regulators in local fruit production 1. Early ripening pear expansion technology Liguoling is a pear fruit expansion agent developed by the Horticulture Department of Zhejiang Agricultural University, which is mainly composed of GA4 and GA7 compound plant growth regulators, which can regulate the content of gibberellin in flowers and fruits, promote the transport of photosynthates to flowers and fruits, increase fruit setting rate, promote fruit expansion, improve appearance and mature ahead of time. The application of this new type of plant growth regulation can make the fruit mature 7 days ahead of schedule and increase the fruit weight by 12% and 40% when the pear tree is coated with 15 mg of "Li Guoling" ointment on both sides of the fruit platform or stalk 25-45 days after flowering. According to the determination of fruit quality in various places, the application of "Liguoling" can obviously reduce the firmness of fruit, promote the crispness of meat, increase the content of soluble solids by 1.5%, and reduce the phenomenon of pear fruit cracking. 2. Grape seedless and expansion technology 2.1.Grape seedless technology at present, the plant growth regulators used in seedless grape production include gibberellin (GA), probiotics (4-CPA) and cytokinins (6-benzylaminopurine (BA), pyruron (CPPU, 4PU, KT30)). The specific methods are as follows: one treatment before flowering and one after fruit setting. For rose dew and other varieties, 14 days before flowering, that is, when the buds at the lower 2cm of the inflorescence began to disperse, the inflorescences were treated with GA solution of 100mg/kg, and then repeated with 100mg/kgGA at 7-14 days after flowering. The purpose of the first treatment was to induce abnormal development of pollen and ovules to form seedless fruits, and the second was to promote the increase of cell volume and fruit size. It was treated once at flowering stage and once after fruit setting. Xianfeng and other varieties had serious side effects before flowering, but delayed to the period from pre-flowering to early flowering, dipping inflorescence with GA of 10~25mg/kg, and then repeated treatment with the mixture of 25~50mg/kgGA and 5mg/kgBA after 15 days. When treating varieties such as Jufeng, in order to reduce the hardening degree of ear axis and increase the seedless rate, the first treatment time can be slightly advanced to 2-5 days before the first flowering, while the second treatment time is a little later, and the GA concentration is 25mg/kg 10-12 days after flowering. 2.2. The technology of grape expansion is generally treated after full flowering, and the main medicament is gibberellin or gibberellin combined with other hormones. The treatment of seedless grape varieties should be carried out at 3-9 days after flowering, and the concentration was 100~200mg/kg, while for seedless grape varieties, 10-15 days after flowering, the concentration was 25~100mg/kg. The practice showed that gibberellin should not be used alone, but should be used in combination with GA3 and KT30 when growth regulators were used to promote the expansion of grape fruit. 3. Seedless and expanding of watermelon in 1995, Japanese researchers treated the ovary of unpollinated watermelon with 200 ml/LCPPU to induce parthenocarpy and produce seedless fruit, and did not affect the fruit shape and soluble solids content of watermelon. Plant growth regulators began to be used in the production of seedless melon. In China, the female flower ovary of unpollinated watermelon was treated with zigualing (the main component is CPPU), and the seedless watermelon fruit was also produced. However, this technology is time-consuming and labor-consuming, and has great side effects, so it is not suitable to be used in production. Cytokinin clopidourea can be used for watermelon expansion, but it should be sprayed on the watermelon embryo on the day the female flower blossoms or 1-3 days before flowering, and should be applied according to the dosage recommended at the time of registration, otherwise it will cause watermelon deformity and fruit cracking. 4. The dwarfing cultivation technology of red bayberry the purpose of dwarfing cultivation of red bayberry is to control the vegetative growth of red bayberry, reduce the operation difficulty of production management measures such as pruning and picking, and reduce the "big and small year" phenomenon of red bayberry fruit. the methods of soil application and spraying paclobutrazol are generally used. The amount of soil application of paclobutrazol was calculated according to the effective components of the shaded area of the crown per m2, and 0.2g~0.4g was the best, which made the growth in a semi-inhibitory state and branch while bearing fruit. Spraying paclobutrazol was carried out after the spring shoot stopped growing, and the best solution was 15% paclobutrazol 200 times. 5. The main component of kiwifruit expanding agent is clopidourea, and the main purpose of using expanding agent is to produce more than 100g large fruit-shaped kiwifruit which is popular in the market. The more scientific application period is 15-25 days after anthesis. The application concentration was 5-8 mg/kg (that is, 50 ml 0.1% chloropyruron to water 6.25~10kg). Spray the fruit noodles evenly with a sprayer, and it is forbidden to dip in the young fruit. The above techniques have been applied in fruit production in Hangzhou area. In addition, growth regulators can also be used in fruit tree breeding, seedling breeding, tree resistance control, fruit quality control and so on. 3. Side effects of plant growth regulators Plant growth agents have side effects in production, and if the time, dosage and method are incorrect, they will bring losses to production: the side effects of Liguoling are not obvious, but the fruit shape of precocious pears produced by Liguoling is large, and the stalks and pedicels are easy to elongate to both sides, and the content of soluble solids increases, but the taste decreases and the pulp is easy to be spongy. The storage time of fruit at room temperature is shortened. Grape should pay attention to the application time when using expansion agent. Early treatment of seeded varieties will lead to some seedless grains, which will affect the perfection of ear; seedless varieties will prematurely treat the hardening weight of fruit stalks. It is time-consuming and labor-consuming to obtain seedless watermelon by exogenous hormone treatment. even if we strictly control the chemical concentration, treatment time and cultivation techniques, there are still some phenomena, such as low fruit setting rate, unstable fruit setting, thick fruit skin, deformed fruit, light taste and so on. it is also easy to produce food safety problems, which is difficult to use in production. Paclobutrazol is abused in the production of red bayberry. Fruit growers often spray high concentration paclobutrazol solution to suppress the growth of red bayberry, which excessively suppresses the vegetative growth of red bayberry, resulting in the gradual decline of the tree and easy to be infected by pathogens, resulting in the occurrence of diseases such as onion disease and withered branch disease, reducing the yield of red bayberry. The treatment of young kiwifruit with expansion can significantly increase the fruit and increase the yield, but at the same time, the appearance of the fruit is distorted, the flavor becomes sour, the pulp firmness fades, the firmness decreases, it is easy to soften, the disease resistance is reduced, it is easy to rot, the storage is not tolerant, and the tree potential is weakened, which has caused serious consequences to the kiwifruit industry in some provinces. Suggestions on the use of plant growth regulators in local fruit production the use of any plant growth regulators is not recommended in fruit production in Hangzhou. The main results are as follows: 1. It is not clear whether synthetic plant growth regulators are harmful to human health as far as possible, and the country lacks relevant standards for the use of plant growth regulators. The supervision system for the production, use and detection of plant growth regulators for agricultural products is not perfect. With the recent "explosion of watermelons" and other incidents, consumers will pay more attention to the use of agricultural additives, and the relevant national regulatory system will be gradually improved. At that time, fruits using growth regulators may not be welcomed by the market. 2. Careful selection and purchase of plant production regulators plant growth regulators belong to the category of pesticides, so producers should not only pay attention to the composition and effect of reagents, but also whether the registration information of key products is reliable. If conditions permit, you should log on to the China Pesticide Information Network to check the authenticity of the product registration certificate number and registration content, and it is best to consult the local agrotechnical extension departments before using plant growth regulators. To avoid economic losses caused by misuse and misuse of growth regulators. 3. Scientific use of plant production regulators from the point of view of actual production, the expansion of early-maturing pears, grapes, kiwifruit, watermelons and other fruits can be achieved through fertilizer and water management. The naturally expanded fruits are full and symmetrical, and the flavor is natural and simple. The use of expansion agents in orchards with improper fertilizer and water management will weaken the trees due to excessive consumption of nutrients. Due to the unstable technology, it is not recommended to use plant growth regulators to produce seedless watermelons, but triploid watermelon seeds can be purchased from seed companies to produce seedless grapes and dwarf bayberry trees. but the concentration and time should be strictly controlled.