Chemical flower promotion and control is to use chemicals to promote or inhibit the growth of flowers, control the flowering time, prolong the life of fresh cut flowers, and control the height and shape of flowers and trees, so as to improve the ornamental value of flowers and trees and make flowers bloom on time out of season according to people's wishes. Chemical substances that promote chemical control are called chemical accelerators, including plant growth promoters, plant growth retardants and plant growth inhibitors.
2. Types of chemical accelerators
(1) plant growth promoter:
① Auxin: It has the characteristics of promoting growth at low concentration and inhibiting growth at high concentration. Include indoleacetic acid (IAA), indolebutyric acid (IBA), naphthylacetic acid (NAA), 2,4- dichlorophenoxyacetic acid (2,4-d), 4-chlorophenoxyacetic acid (PCPA), 2,4,5-trichlorophenoxyacetic acid (2,4,5-t) and so on. Main functions: a. Promote plant height. B. promote rooting and improve the success rate of cutting. C, inhibit shedding, prevent fruit trees from falling flowers and fruits, and improve the fruit setting rate. D. maintain the top advantage of plants. E. prolonging plant dormancy. F. promote the formation of female flowers.
② Gibberellin (GAI): also known as gibberellic acid (GA3). Main functions: a. Promote plant height. B. Overcome dwarfism. C, inducing the flowers to bolt and bloom in advance. Induce the formation of male flowers.
③ Cytokinins include zeatin, kinetin, 6- benzyladenine (BA, BAP, 6-BA) and tetrahydropyranyl benzyladenine (PAB). Main functions: a. Promote cell division and expansion. B. promote organ differentiation. C. delay aging and shedding. D, removing or retaining the top edge, and controlling the plant shape of flowers and trees.
④ Ethylene: It is a natural plant hormone with strong physiological activity. Commonly used ethylene generators are ethephon (CEPA), 1- aminocyclopropane-1- carboxylic acid (ACC), aminooxyacetic acid (AOA) and silver nitrate. Main functions: a. influence the development of flowers. B, extend the storage period of cut flowers to prevent aging.
(2) Plant growth retardants: CCC, hydrazide, paclobutrazol (PP333), mepiquat chloride, Bijiu (B9), etc. The main functions of these drugs are shortening internodes, making stems stout, deepening leaf color, thickening leaf skin, increasing the number of lateral branches and developing root systems.
(3) Plant growth inhibitors: mainly including fresh blue (MH), plastin and triiodobenzoic acid (TIBA). Main functions: A. Destroy the top advantages of flowers and trees, inhibit the height of plants, and make them form bulls. B. Make the stems short and thick, the leaves dark green, the leaves small and thick, the side branches increase and the roots develop.
3. Preparation of chemical accelerator
Because some chemical accelerators are insoluble in water, they should be prepared by different dissolution methods. First, indoleacetic acid, indolebutyric acid, naphthylacetic acid and gibberellin can be dissolved in a small amount of 95% alcohol, and then a certain amount of water can be added to achieve the required concentration. Cytokinins such as 6-BA can be dissolved by heating with a small amount of hydrochloric acid with a concentration of 1 mol, and then a certain amount of water is added to make it reach the required concentration. The preparation methods of several common chemical accelerators are introduced.
Sodium salt of auxin: If plant growth regulators such as 2,4-D, naphthylacetic acid or PCPA are used in the form of sodium salt, weigh the sodium salt of 1g, put it in a beaker, first add a little water to dissolve it, stir it with a glass rod until it is completely dissolved, and then add water to 500ml, which is a 2× 10-3 aqueous solution.
Auxin protoacids: If protoacids such as 2,4-D, naphthylacetic acid, anticonvulsant, indoleacetic acid or indolebutyric acid are used, weigh raw powder 1g, put it in a beaker, add a little water, drop 1% phenolphthalein 1 ~ 2 drops, and then slowly add it with 5% sodium hydroxide solution. Add water to 1000ml to form a solution with the concentration of 1× 10-3, and then mix it with water according to the use concentration.
Gibberellin: weigh 0.2g of gibberellin powder, put it into a beaker, add a small amount of 95% alcohol, stir until it is dissolved, and then add water to 200ml, which is the gibberellin solution of 1× 10-3.
NAA: Weigh 0.2g of NAA, put it in a beaker, add a small amount of 95% ethanol, stir until it is dissolved, and then add water to 200ml, which is the NAA solution of 1× 10-3.
Activin: Weigh 0.2g cytokinin, put it in a beaker, add 1% dilute hydrochloric acid, stir until it is dissolved, and then add water to 1000ml, which is 2× 10-4 cytokinin stock solution.
Celastrol: Weigh 2g of Celastrol in a beaker, add a small amount of triethanolamine, heat with low fire, stir until it is completely dissolved, and then add water to 1000ml to obtain a 2× 10-3 Celastrol solution.
Bi Jiu: Put a small amount of hot water in a beaker, pour in B 92g, stir while heating until it dissolves, and then add water to 500ml to get 4× 10-3 B 9 stock solution.
4. Correct use of chemical accelerators
The most commonly used methods are foliar spraying and soil irrigation, as well as local treatment, such as drip irrigation, injection, root soaking, ball soaking and fruit soaking. According to the need to master the concentration of use, but also pay attention to the right medicine, in order to achieve the ideal effect.
Dip method: This method is simple and easy to learn. 20 ml of alcohol is slowly poured into 50 ml of 3000× 10-6 NAA solvent, and fully stirred evenly. Rose, carnation or chrysanthemum cuttings are selected, and the lower part of the cuttings is about 2.5 cm in the solution for 5 seconds, and the dried liquid medicine is taken out and immediately inserted into the substrate.
Dip in powder method: prepare the growth regulator into powder, cut off branches and cut again, soak the lower part in about 2.5cm water, immediately dip in powder, shake off excess powder, punch a hole in the cutting substrate with a wooden stick thicker than the cutting, gently insert the cutting with powder into the hole, and compact the surrounding substrate by hand.
Soaking method: Soak the lower part of the cuttings about 2.5cm in the solution containing plant growth regulators 1 ~ 24 hours. The soaking time is inversely proportional to the concentration of chemicals, and the air humidity should be high during soaking to ensure the cuttings to absorb chemicals slowly and steadily. After soaking, take out the cuttings and insert them directly into the substrate.