Application of Plant Growth Substances in Orchid Cultivation

Mr. Zhao Guang, a fellow orchid enthusiast, raised the questions of inducing Chinese orchids to produce more shoots and inducing them to root. With today's level of technology, these problems are not difficult to solve. Professor Zou Qi, former president of Shandong Agricultural University, and Professor Gao Huiyuan, in collaboration with Yuanxin Orchid Garden, treated Chinese orchids with a-naphthaleneacetic acid to induce rooting and achieved good results. Plant growth substances can be divided into plant hormones (synthesized within the plant body) and plant growth regulators (artificially synthesized substances with plant hormone activity). Plant hormones can be divided into five categories: 1. auxins, 2. gibberellins, 3. cytokinins, 4. ethylene, 5. abscisic acid. Auxins Discovered by Charles Darwin of England in 1880. It has now been proven that indoleacetic acid is the most common, present in bacteria, fungi, algae, ferns and seed plants. It is widely distributed in higher plants, in roots, stems, leaves, flowers, fruits, seeds and coleoptiles, mainly in the vigorously growing parts. Its main functions are promoting wound healing and the formation of adventitious roots, etc. At present it is mostly used to induce rooting of cuttings. Among these, the artificially synthesized a-naphthaleneacetic acid (NAA) and indolebutyric acid (IBA) are the most widely used; the former acts for a short time and induces few, thick, short roots, while the latter acts for a long time and induces many, thin, long roots, so a combined application of the two is most ideal. Cytokinins Both plants and microorganisms contain cytokinins, more than 20 kinds in total, among which zeatin was first extracted from immature seeds of sweet corn in 1967; there are also zeatin riboside, dihydrozeatin, isopentenyladenosine, etc. The cytokinins of higher plants mainly exist in the parts where cells are dividing, such as shoot tips, root tips, immature seeds, germinating seeds and growing fruits, etc. Based on the structure of kinetin, a large number of derivatives have been artificially synthesized, all of which have the effect of promoting cell division; the commonly used ones include kinetin, 6-benzyladenine, tetrahydropyranyl benzyladenine, diphenylurea, etc. Its main functions are promoting cell division, shoot differentiation and bud growth, etc. At present, 6-benzyladenine (6-BA) and kinetin are mostly used in tissue culture. If they are used to induce Chinese orchids to produce more shoots, experiments should be carried out to select the appropriate type, concentration and method of use. Address: Beside Langmaoshan Reservoir, Caishi Town, Licheng District, Jinan City Yuanxin Orchid Garden, Wang Tao Postcode: 250103