Preparation and Methods of Use of Growth Regulating Substances (2)

In addition to sunlight, water and nutrients, the growth of flowers and ornamental plants also requires various growth regulating substances. Although the amounts needed are very small, they play a very important regulatory role in the growth, development and metabolism of flowers and ornamental plants. In flower production, certain hormones can be added artificially to control growth, promote rooting, break dormancy, cultivate strong seedlings, dwarf the plant form, control flowering, enhance resistance, and prevent flower and fruit drop and leaf drop. Growth regulating substances can generally be divided into 5 categories: ① Auxins Mainly indoleacetic acid (LAA), indolebutyric acid (IBA) and naphthaleneacetic acid (NAA), etc. They can promote cell division and elongation, promote rooting, delay the formation of abscission layers in leaves, flowers and fruits, and promote parthenocarpy, etc. ② Gibberellins Gibberellin (GA) is a natural plant hormone. It promotes stem and leaf elongation, breaks dormancy, promotes flower bud formation, promotes flowering, and prevents organ abscission, etc. ③ Cytokinins Mainly kinetin (KT), 6-benzyladenine (BA) and zeatin (ZT), etc. They promote cell division and enlargement, prevent organ senescence, break dormancy, and promote fruit growth, etc. ④ Ethylene Inhibits the growth of stems, buds and roots, promotes flower bud formation and lateral bud sprouting, affects flowering period and sex differentiation, and can cause fruits to ripen rapidly. ⑤ Growth inhibitors Include daminozide (B9), chlormequat (CCC), maleic hydrazide (MH), etc. They can slow down the speed of cell division and elongation in stems or branches, and inhibit the lengthening growth of plants and branches. (Jiang Chengzi)