Preparation and Use of Plant Growth Regulating Substances (Part One)

Some growth regulating substances are insoluble in water, so different dissolution methods should be used. Indoleacetic acid, indolebutyric acid, naphthaleneacetic acid, gibberellin, etc. can first be dissolved in a small amount of 95% alcohol, and then a certain amount of water added to reach the desired concentration. For the preparation of naphthaleneacetic acid at different concentrations, refer to Table 8. Cytokinins such as kinetin and 6-benzyladenine can first be dissolved in a small amount of 1 molar hydrochloric acid, and then a certain amount of water added to reach the desired concentration. The original powder of maleic hydrazide is insoluble in water; it can first be dissolved in triethanolamine (heating is required during dissolution), and then diluted with water. The prepared stock solution should be stored in a refrigerator at 2-4°C, and taken out for dilution and preparation when needed. Hormone solutions not used up for the time being should be stored at low temperature and in the dark. There are many methods for using growth regulating substances, and they also vary depending on whether they are liquids or powders. ① Spraying method The agent has a wide contact area, high efficacy and good effect, and is a very commonly used method. ② Dipping method Used for local treatment; for example, to promote rooting of cuttings, the base of the cutting is dipped in auxin, which has the advantages of concentrated action and saving agent. ③ Smearing method The site of agent application can be strictly controlled to avoid diffusion, and it also has the advantage of saving agent. ④ Pouring method The method of soil pouring is used to treat flowers; because it is easily dispersed and lost, the agent is rather wasted. In the cutting propagation of flowers, in order to promote rooting of cuttings, increase the survival rate, speed up propagation and cultivate strong seedlings, hormone treatment is often used. Hormones that promote rooting include indolebutyric acid (IBA), indoleacetic acid (LAA) and naphthaleneacetic acid (NAA), etc., especially naphthaleneacetic acid, which has stable performance and strong action, is used more often. There are two treatment methods: soaking in aqueous solution and smearing with powder. Soaking in aqueous solution is divided into low concentration and high concentration. Low-concentration aqueous solution soaking means soaking the cuttings for a relatively long time before planting. The concentration of naphthaleneacetic acid used is 10-200 mg /L, and the treatment time is from 8 hours to 24 hours. Soaking at 1-2 cm at the cut end is sufficient; it is not necessary to soak the entire cutting. Young branches are treated with relatively weak indoleacetic acid, and mature branches are treated with indolebutyric acid or naphthaleneacetic acid. High-concentration rapid dipping treatment can increase work efficiency; the commonly used concentration is 1000-10000 mg/L, and soaking for 2-5 minutes is sufficient. Powder treatment is to first dissolve the agent in a small amount of 95% alcohol, then evenly sprinkle and mix the dissolved liquid into inert powder such as talcum powder, then heat slightly so that the alcohol evaporates, and it becomes a powder. Usually 1 gram of talcum powder is mixed with 1-20 mg of auxin. During treatment, dip the base of the cutting that has been moistened with water into the powder once, but the treatment concentration is 10 times higher than when soaking in solution. There are many kinds of flowers; in specific application, a small amount of hormone can be tested first. Generally, the concentration for herbaceous flowers should be lower, and for woody flowers it can be higher. The concentration for long soaking treatment should be lower, and for rapid dipping it can be higher. Treatment of Flowers for Dwarfing and Strengtheningcultivationoften, because the plant's vegetative growth is too vigorous, the plant is tall, and the branches and leaves are excessively luxuriant, the reproductive growth such as flowering and fruiting is affected, greatly affecting the ornamental value and affecting the arrangement of flower beds, etc. Therefore, incultivationeveryone hopes for short and strong plants, dense flowers, and full plants, so as to achieve the expected effect. Usually various growth inhibitors or retardants can be used to inhibit elongation growth and dwarf the plant type, so as to achieve the purpose of improving disease resistance, drought resistance and cold resistance, and promoting branching and flower bud differentiation. After treatment, chrysanthemums can be dwarfed, branching promoted, and flowers concentrated. After treatment, rhododendrons can delay vegetative growth and accelerate flower bud formation. After treatment, the height of geraniums can be reduced by 10 cm, and flowering is advanced by 2 weeks. After treatment, dahlias can also be dwarfed and flower earlier. (Jiang Chengzi)