Effect of Moisture Content of Growing Media on Crop Growth

Chinese orchids must have water to maintain their growth and nutrient absorption and transport, and to carry out normal metabolic processes. Chinese orchids are semi-epiphytic shade-loving plants. During their growth, a small portion of the water they need is absorbed from moisture in the air through the leaves, but most of the water must be taken up from thegrowingmedium, supplying the Chinese orchids' growth and the production of new organic matter. Chinese orchids not only rely on their leaves for photosynthesis to produce energy, but their root systems carry out respiration to absorb oxygen from the pores of the medium in the orchid pot. If the moisture content in the medium in the orchid pot is too high, water will fill the medium's pores, causing waterlogging; when the medium's pores in the pot are filled with water and lack oxygen, the roots become oxygen-deficient and suffocate, and the root system is prone to rotting. If the moisture content of the medium in the orchid pot is too high, fresh oxygen cannot enter the medium's pores from outside the pot for gas exchange. In order to obtain fresh oxygen for their normal physiological functions, the roots of Chinese orchids will show a phenomenon in their growth - that is, most of the roots of Chinese orchids will extend along the wall toward the pores at the edge of the orchid pot and grow around it, or grow toward places above the pot that have fresh oxygen; while the roots in the middle part of the medium in the orchid pot, where the moisture content is high and aeration is poor, lose their semi-permeability due to the lack of oxygen supply and lose the original functions of the root system. At this time, because anaerobic pathogenic bacteria multiply in large numbers, they take the opportunity to invade and cause harm. In addition, because a large amount of toxic substances accumulates and poisons the root system, the life activities of beneficial microorganisms are restricted and they cannot decompose intermediate products for the root system to absorb; the functions of the root system gradually lose, reducing the root system's ability to absorb water and nutrients, and over time the root system will rot and die because of this, indirectly affecting the growth of the stems and leaves of Chinese orchids. In general, the amount of moisture content in a medium is closely related to its physical characteristics and particle size. The larger and more numerous the particles, the more non-capillary pores there are, water is easily lost from the pores, and water is relatively difficult to retain; the smaller the particles, the more capillary pores there are, water is relatively less likely to be lost under the influence of gravity, water is relatively easy to retain, and therefore the water-holding capacity is higher. After a large-particle medium is filled and planted with orchid plants, many spaces form between the particles, making water easy to lose, so water and liquid fertilizer management must be very careful; after a fine-particle medium is filled into an orchid pot for planting, its water-holding capacity is good and its aeration becomes poor, so water management must be given special attention, otherwise it easily causes oxygen deficiency in orchid roots and poor growth. Among common media, those with larger particles include coarse Japanese stone, coarse sand, coarse perlite, mineral silica, long strips of osmund fiber, and coarse brick pieces; fine-particle media include peat soil, artificial soil, wood chips, fine osmund fiber, and so on. The larger the particles, the poorer the water-holding capacity, and the root system of Chinese orchids is prone to water deficiency and growth stagnation; the finer the particles, the higher the moisture content, oxygen diffusion is restricted, and the root system of Chinese orchids is prone to oxygen deficiency and rotting. Therefore, by using an appropriate amount of coarse-particle medium and fine-particle medium together, aeration and water retention can be increased, sufficient oxygen and abundant water can be supplied to the root system, and the frequency of fertilization can be reduced, so that Chinese orchids can grow and develop in a balanced way.