TREATMENTS ACCELERATING DEVELOPMENT AND FLOWERING
Most ornamental plants are grown for their flowers, therefore, to bring about an abundant flowering at the right time is the goal of the florist's efforts. The flowering time depends on the one hand - the nature of these plants, on the other - the conditions, in which they are located. Understanding the factors of internal and external nature will allow you to effectively manage the development and flowering of many ornamental plants.
Light and temperature are a factor in the flowering cycle and development of ornamental plants. A close relationship between flowering of some ornamental plants and the length of day and night was found. This phenomenon is called a photoperiod. A study by botanists showed the existence of plants that bloom only at 14 hours, that is, long, day. They are the so-called. long day plants, to which they belong: malwa, baby girl, snapdragon, larkspur, balsamine, poppies and other plants that bloom in spring or in the first half of summer.
Plants that bloom in autumn belong to the so-called. short day, among them can be mentioned: amaranth, gilding, dahlias, goldenrod. spurge, ash pan and others. There is also a group of photoperiodically indifferent plants.
Period of time, during which the plant should be exposed to light, necessary to induce its flowering, is called the period of photoperiodic induction. Knowing the length of this period is essential for artificially regulating the flowering time. It turned out, that artificial lighting with neon lamps, mercury or incandescent plants of a long day during short days, it can adequately accelerate flowering and vice versa - shorten the day to 8-10 hours by shading, favors early flowering of plants in a short day. The detailed knowledge of the length of the photoperiods allowed to introduce new production methods into gardening practice, like for example. year-round cultivation of pyrethrum and other plants.
Temperature is closely related to the influence of light on flowering. Today science confirms that there is a close correlation between species-specific temperature and light requirements during the transition from vegetative to generative development.. Some researchers make the passage of these processes dependent on the production and existence under strictly defined conditions of a specific substance, the so-called. florigen - the flowering hormone. So far, it has not been possible to isolate such a substance, but its existence seems incontrovertible. The discovery of it will undoubtedly allow for a fuller understanding of the processes leading to flowering, which will undoubtedly be of great importance for the gardening practice.
The second group of issues related to the regulation and acceleration of flowering of ornamental plants in their development cycle is created by the existence of periods of growth and rest.
It is of great importance for plant producers to know their growth and rest periods, especially with the so-called. forcing the plants, i.e.. forcing them to start growing and flowering then, when they are going through a period of dormancy. Research on the rhythmicity of plant growth indicates the existence of an absolute rest period, caused by the intrinsic properties of the plant, and the period of relative rest, caused by unfavorable climatic conditions. In order to break the relative dormancy, it is enough to create favorable conditions for the plants to grow. On the other hand, absolute rest, which is caused by the build-up of inhibitory substances, can be interrupted by special treatment, such as etherization, warm baths or low temperatures. In our company, it is practical to interrupt absolute sleep using the hot bath method (or pairing) and freezing.
The etherization method and the use of hydrogen cyanide require special equipment and great care because of the ease of causing fire or poisoning.
Rushing by the method of warm baths
Brushing by this method consists in bathing the whole plants or their shoots for 9-12 hours in water at a temperature of 30-40 °. The duration of the bath depends on the time of forcing and the type of plants being driven.
The action of water baths and etherization is strictly local and causes the dormancy of only these shoots or their parts to be interrupted, which have undergone the treatment.
Brushing with steam
It is a modification of the warm bath method. It consists in placing the driven plants, e.g. lilacs in a hot greenhouse at 43 ° C and sprinkling whole plants every half hour. At night, the temperature is lowered to 30 ° C and sprinkled less often. We use such a high temperature when forcing lilacs at the beginning of October. For forcing them in November, a temperature of 38 ° C is sufficient, in December 33 ° C, and in January only 28 ° C. We only maintain this temperature during the first week. We gradually lower it over time, so that it is around 16 ° C during flowering.
Rushing by freezing
This is the most common method of breaking the dormant period. Plants intended for forcing, and in the period of absolute rest are placed for the period from 2 do 5 weeks in cold stores with a temperature of 0 do + 5°. The length of the cool-down period depends on the depth of rest. As it passes by, we shorten this period. After the treatment, the plants are subjected to normal forcing.