Concentration of culture medium solution

The matrix solution contains a certain salt and has a certain water potential. The matrix water potential is higher than the root cell water potential, so the root system can absorb water very well. In serious cases, it will make the orchid plant "burn to death". Because the cultivation medium of Chinese orchid is special, its buffer capacity to salt is weak, and it is easy to cause the concentration of substrate solution to be too high, so it should be applied more thinly when applying fertilizer.

Chinese orchids have relatively strict requirements for the moisture of the cultivation substrate, and it is difficult for beginner growers to grasp. Is there an index for quantifying the moisture of the cultivation substrate? What is the water content of the most suitable culture medium? According to the tests of scholars, if the substrate with 51.66% of the water content of the cultivation substrate reaches 100% of the maximum water holding capacity of the substrate, the optimum water content of the cultivation substrate for growth is 70%-90% of the maximum water holding capacity of the substrate, and the growth rate and photosynthetic rate are the highest at that time, that is, the water content of the cultivation substrate is 36%-46%. If it is less than 50% of the maximum water holding capacity, the growth will be blocked or even die. Therefore, when watering or replenishing water to Chinese orchids, we can refer to this index for quantitative management, especially in some advanced orchid planting sites, we can carry out automatic control of water management according to this index, especially suitable for drip irrigation.

The process of water absorption and transpiration of orchid forest is the two ways of water exchange between orchid plant and external environment, and water transport makes these two ways closely linked. The water in the orchid plant is kept in balance through water absorption and transpiration, so that all life activities can be carried out normally.

Transpiration will make orchid plant lose a lot of water, but it is the power of passive water absorption, root pressure alone can not maintain the balance of water metabolism, there must be a strong pulling force formed by transpiration to make water absorption or rapid increase. Plants promote the absorption and transmission of mineral elements in the body through transpiration, so that the salts dissolved in water are rapidly distributed to various parts. And transpiration can reduce the leaf temperature. If the plant temperature exceeds a certain limit, it will affect the normal physiological activities. Transpiration consumes a lot of heat energy due to water vaporization, so it can reduce the temperature of the leaves so that they will not be "burned" in the hot sun. If the root system of the leaves of the orchid plant is not sound, it is often easy to burn the leaves in a climate with strong transpiration, so pay attention to this problem when I cultivate it.

In the event of frost, because the leaves have a thin layer of frost, if the transpiration of orchid roots is weakened, the leaves will be frostbitten, especially the older leaves, mainly due to the weakening of water absorption and transpiration of aged leaves. To this end, in this weather, before frosting and melting, draw well water to spray leaves to make it melt. This mainly promotes the frost layer to absorb the heat in the water and disintegrate, without absorbing the heat of the leaves, to maintain the body temperature of the orchid leaves, so that the orchid leaves remain intact and avoid frostbite.

The stomata of orchid leaves can be opened and closed freely to spread water vapor to regulate transpiration. Therefore, the structure of leaves and the opening degree of stomata are closely related to transpiration. Because the leaf area of Cymbidium is large, the leaf is softer, and the transpiration of the leaf with thin stratum corneum is greater, which is less than that of Chunlan and Hanlan. On the other hand, because of the thick cuticle, the transpiration of C.hoorerlanam is weaker, and the requirement for water is less than that of Cymbidium. On the other hand, the transpiration of different varieties of the same species is different because of different leaf structure, which leads to different water management measures. Therefore, there should be pertinence in management.

However, in addition to leaf structure and other internal factors affecting transpiration, it is also affected by external environmental conditions. (Liu Zhongjian, Xu Gongming)