Differences Between Contaminants and Biological Contamination in Growing Media

Generally, the growinggrowingmedia used by domestic orchid enthusiasts are none other than: Japanese stone, perlite, silica stone, expanded clay pebbles, Shilin stone, tile pieces, brick pieces, gravel, styrofoam, synthetic gas skin, artificial stone, tree fern fiber, peat moss, bark, sphagnum moss, and other agricultural waste and other inorganic or organic materials asgrowingmedia. How to choose and provide an excellentgrowingmedia environment is the most important topic in cultivating Chinese orchids. However, the media materials currently used in Chinese orchid cultivation are generally chemically synthesized or taken from nature, and the media materials themselves often carry contaminants, such as pathogens, insect eggs, pigments, heavy metal contamination, pesticide residues, toxic substances, and so on. If Chinese orchid growers use them rashly before planting without taking preventive measures in advance, root rot is often easily caused. Generally, the pH value of peat moss is below 4, and some may carry pathogens and nematodes. When planting Chinese orchids, if disinfection and lime addition are not done in advance, or lime is not used to adjust the M value, root growth is easily restricted. Bark contains some resins, tannic acid and phenolic compounds. Before planting, if one does not select bark that has been fully piled, rotted and completely fermented, these toxic substances will remain and will inhibit lateral bud germination and root growth, and will poison the root system, causing roots to be thick and short, few in number, with few root hairs and slow growth; when a large amount is used, it even causes the root tips to brown or blacken, rot and die. The important biological aspects of media include the presence or absence of beneficial microorganisms and harmful microorganisms. The microbial content in media has a certain proportion, and among microbial species, living densities will mutually antagonize and compete for space. When the amount of beneficial microorganisms is large, they can secrete growth hormone types, promoting root development and the growth hormones required for stem and leaf growth, and inhibit the breeding of pathogenic bacteria; when the amount of harmful microorganisms is large, transmissible pathogenic bacteria such as Phytophthora and Rhizoctonia will form dominant bacteria, causing severe disease in the root system, stems and leaves. Therefore, excellent, healthy and strong Chinese orchids must have good media, combined with the grower's good management environment and methods, in order to cultivate better results. Chinese orchids grow for a long time in the limited media of small pots. If there are no good biological microorganisms, the growth of Chinese orchids is more easily restricted. When ordinary orchid enthusiasts mention the media currently used for cultivating Chinese orchids, is the method of applying high-temperature treatment before planting to kill disease, insect and bacterial pests that hinder the growth of Chinese orchids appropriate? If the planting materials currently used for cultivating Chinese orchids are treated by high-temperature disinfection, both beneficial microorganisms and harmful microorganisms will be greatly reduced. Before planting Chinese orchids, growers need to add beneficial microorganisms in advance to control the reproduction amount of harmful microorganisms. If this preventive measure is not done in advance, and the planted stock itself carries transmissible pathogens, and there are no microorganisms at all in the media, then it cannot antagonize the reproduction of transmissible pathogens, and harmful pathogenic bacteria cannot be inhibited in competing for living space. When they multiply in large numbers and reach a certain harm index, they will quickly cause damage in a short time, causing severe rot in the root system, stems and leaves. Whether the aeration, water retention capacity, pH value, cation exchange capacity, buffering capacity and biological properties of the growing media are good will all affect the root system's absorption and transport of water and nutrients and the ability of stems and leaves to photosynthesize and store energy. Choose a growing media suitable for the growth of Chinese orchid roots, then through appropriate blending, and piling and fermentation, fully decomposing, reducing toxic substance content, increasing the buffering capacity of the media and the population of beneficial microorganisms, and reducing the occurrence of harmful pathogenic bacteria. In this way, root development will have a good environment, and ideal Chinese orchids can be cultivated.