Composition for inhibiting flowering of plants and composition for prolonging duration of flowering of plants

Abstract: A composition for inhibiting flowering of plants and a composition for prolonging the duration of flowering are disclosed. The compositions of the present invention comprise S-(+)-abscisic acid as an effective ingredient.

Description: The present invention relates to a method of inhibiting flowering of plants. Most agricultural and horticultural plants form flower buds and then flower depending on the change of season, especially change in the length of the daytime. To inhibit the formation of flower buds or flowering is an important agricultural technique. No technique has been established to completely inhibit the floral bud initiation by using plant hormones. Only one commercially used technique is to inhibit floral bud initiation by artificially controlling the length of the daytime wherein the plants (for example, chrysanthemum) are cultured in special equipment. However, to artificially control the length of daytime while culturing the plants in such equipment is costly and the scale of the culturing is limited. Thus, if the floral bud initiation of plants in a field can be inhibited by applying an agricultural chemical to the plants, it is economical and advantageous. To attain this object, a number of compounds have been tested for their activities in inhibiting the flowering of plants. A number of reports have been published concerning the effectiveness of synthetic racemic abscisic acid for this purpose (Ann. Rev. Plant Physiol. 39, 175 (1988)). However, the results have been negative and no useful technique has been established, which employs synthetic racemic abscisic acid. Accordingly, the present invention seeks to provide a method for inhibiting flowering of plants. It was surprisingly found by the present inventors that S-(+)-abscisic acid inhibits the flowering of plants if applied by drenching or spraying before floral bud initiation. Thus, the present invention provides a method of inhibiting flowering of a plant comprising drenching or spraying the plant with an effective amount of S-(+)-abscisic acid before floral bud initiation of the plants. For drenching the S-(+)-abscisic acid is applied in an amount of 0.1-50 ppm and may be applied in an amount of 5-25 ppm, while for spraying the (S)-(+)-abscisic acid is applied in an amount of 10-1000 ppm and may be applied in an amount of 125-500 ppm. The present invention enables, for the first time, effective inhibition of the flowering of plants, especially agricultural and horticultural plants, by applying a chemical to the plants. Thus, the present invention will make a great contribution to agriculture and horticulture. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present specification and appended claims, the term "inhibit flowering" means to completely inhibit the floral bud initiation or flowering after formation of flower buds, or to delay the floral bud initiation and/or flowering. A composition suitable for inhibiting flowering of plants in accordance with a method embodying the present invention comprises S-(+)-abscisic acid as an effective ingredient in an agriculturally acceptable carrier. S-(+)-abscisic acid is a known compound and my be produced by a conventional method (S. Marumo et al., Agric. Biol. Chem ., 46, 1967 (1982); JP-A-296697/88 and JP-A-296696/88). The composition for use in a method embodying the present invention may be formulated by using one or more conventional agriculturally acceptable carrier(s). Examples of the agriculturally acceptable carriers which may be employed include solid carriers such as clay, talc, bentonite, kaolin, diatomaceous earth and silica; and liquid carriers such as benzene, xylene, toluene, kerosene, alcohols (methanol, ethanol, isopropanol, n-butanol, ethylene glycol, propylene glycol and the like), ketones (acetone, methylethyl ketone, cyclohexanone and the like) and N-methylpyrrolidone. The composition may be formulated using one or bore of the above-mentioned carriers and one or more suitable surfactants, and if desired, other additives such as stabilizers and spreading agents. To stabilize the composition or to promote the effect of the composition, the composition for use in a method embodying the present invention may comprise other agricultural additives such as spreading agents, wetting extenders, dispersing agents, sticking agents and disintegrators. The composition may be applied to the plants directly or after dilution with an appropriate diluent such as water or an organic solvent. The composition may be applied to the plants after mixing with other agricultural chemicals such as insecticides, germicides, plant growth regulators and the like. The composition of the present invention may be applied, for example, by spraying the composition to the leaves and stems of the plants or by drenching the plants with the composition. The concentration of S-(+)-abscisic acid in the composition or the diluted composition to be applied to the plants may usually be 0.01 ppm to 1000 ppm. The preferred concentration varies depending on the plant to be treated and on the method and timing of treatment. In cases where the composition is sprayed onto the plants, the composition may usually be diluted to attain the concentration of S-(+)-abscisic acid of 10 - 1000 ppm. In cases here the composition is used for drenching the roots or for hydroponic culture, the composition may usually be diluted to attain the concentration of S-(+)-abscisic acid of 0.1 - 50 ppm. The amount of the composition of the present invention to be applied to the plants varies depending on the plant and the size of the plant, and the suitable amount for a given plot may easily be determine by routine experiments. For example, the amount of the composition of the present invention to be applied to a radish grown in a farm when the composition is sprayed, about 100 liters of the composition may be applied per 10 ares. The composition of the present invention may be applied to the plants one month before, up to the floral bud initiation. In order to completely inhibit the formation of the buds, the composition of the present invention should be applied to the plants before the floral bud initiation. The method of the present invention may be used for a wide variety of plants. Examples of the plants which may be treated by the method of the present invention may include petalous flowers such as chrysanthemum and rose; vegetables such as spinach, radish, perilla and cabbage; and fruits and forest trees such as apple, orange, cryptomeria and cherry. The invention will now be described by way of examples thereof. Unless otherwise specified, all parts and percentage in the Examples are by weight. Example 1 Formulation of Liquid Composition Ten parts of S-(+)-abscisic acid and 90 parts of ethanol were mixed to obtain a liquid composition according to the present invention. Example 2 Formulation of Liquid Composition Twenty parts of S-(+)-abscisic acid, ten parts of polyethylene glycol monolaurate which is a surfactant, 70 parts of propylene glycol monoethyl ester which is a solvent were mixed to obtain a liquid composition according to the present invention. Example 3 Effect for Inhibiting Floral Bud Initiation of Japanese Morning Glory (Short-day Plant) Seeds of Japanese morning glory ( Pharbitis nil , variety: Violet) were sown in pots with a diameter of 4 cm which contained vermiculite packed therein. The plants were grown in a greenhouse under a long-day regimen with a photoperiod of 16 hours, under which conditions flower buds are not formed. The photoperiod of 16 hours was attained by the aid of an artificial supplemental light source (5000 lux). Five days after germination, dark (short-day) treatment of 15 hours was performed to promote the formation of the flower buds. Five hours before the short-day treatment, the composition prepared in Example 1 was used for drenching the plants after dilution to attain the concentrations of S-(+)-abscisic acid shown in Table 1. Twenty milliliters of the diluted composition was used for the drenching per one pot. Alternatively, five hours before the short-day treatment, the liquid composition prepared in Example 2 was sprayed onto the plants after dilution to attain the concentrations of S-(+)-abscisic acid shown in Table 1. Ten milliliters of the diluted composition was sprayed per 10 young plants. On the net day of the short-day treatment, the plants were transplanted to pots with a diameter of 7 cm containing soil packed therein and were cultivated under a long-day regimen with a photoperiod of 16 hours. Fourteen days after the transplantation, the number of formed flower buds was counted and the average number of flower buds per one plant was calculated. For comparison, the same experiments as mentioned above were repeated except that the composition used had the same composition as that prepared in Example 1 except that synthetic racemic abscisic acid was used in place of S-(+)-abscisic acid (Comparative Example 1). The number of flower buds per one plant is shown in Table 1. Each value is the average of 10 plants. As shown in Table 1, the floral bud initiation was completely inhibited by using 5 ppm of S-(+)-abscisic acid in case of drenching and 125 ppm of S-(+)-abscisic acid in case, of spraying. In contrast, in Comparative Example 1 in which racemic abscisic acid was used, the floral bud initiation was not completely inhibited either by drenching or spraying. Example 4 Effect for Inhibiting Floral Bud Initiation of Radish and Perilla Radish ( Raphanus , variety: Taibyo-soubutori) which is a long-day plant was grown under a long-day regimen with a photoperiod of 16 hours in a greenhouse so as to promote the formation of flower buds. Germinated seeds of radish were kept under a low temperature condition (5°C) for 20 days before sowing. Perilla (variety: Aojiso) which is a short-day plant was grown under a short-day regimen with a photoperiod of 10 hours in a greenhouse, In either case, pots of 7 cm diameter containing vermiculite were used and each pot carried one plant. The liquid composition prepared in Example 1 was mixed with a liquid fertilizer so as to attain the concentration of S-(+)-abscisic acid of 10 ppm, and the roots of the plants were drenched with the mixture every three days from the cotyledon phase. For comparison, the liquid fertilizer alone was used for the drenching (Comparative Example 2). The state of growth on 25 days after the start of the treatment are shown in Table 2. In Comparative Example 2 wherein the plants were not treated with S-(+)-abscisic acid, the plants, either radish and perilla, started to flower after 25 days from the start of the treatment. In contrast, by treating the plants 4 or 6 times with 10 ppm of S-(+)-abscisic acid every three days after the plants in Comparative Example 2 started to flower, the floral bud initiation was completely inhibited.

Claims: A method of inhibiting flowering of a plant comprising drenching the plants with 0.1-50 ppm of S-(+)-abscisic acid before floral bud initiation of the plant. A method according to claim 1, wherein the plant is drenched with 5-25 ppm of (S)-(+)-abscisic acid. A method of inhibiting flowering of a plant comprising spraying the plant with 10-1000 ppm of S-(+)-abscisic acid before floral bud initiation of the plant. A method according to claim 3, wherein the plant is sprayed with 125-500 ppm of (S)-(+)-abscisic acid.

Inventors: KAMURO YASUO, MARUMO SHINGO, KAMURO, YASUO, MARUMO, SHINGO
Applicants: TORAY INDUSTRIES, TORAY INDUSTRIES, INC.
Application year: 1991
Main classification: A01N49
IPC codes: A01N37, A01N49