The importance of studying the growth of crop roots The concern for crop yield and quality in agricultural growth is always in the first place, and there are many factors that determine crop yield, such as soil fertility, seed quality, soil moisture content, pest and disease control, and root water absorption. In order to absorb nutrients and moisture around the roots of crops, scientists have done a lot of scientific research and provided a favorable basis for our agricultural production. For a long time, crop science has done a lot of research on the formation of yield, and on the regulation and control of the structure and function of some parts of the crop's ground and its leaf light system. The underground part, despite its long-time attention, is limited to the workload and methodological reasons, and systematic research in this area has not been carried out in China. The development of modern science and technology has enabled scientists to systematically study the root growth processes of more than a dozen crops such as wheat, corn, sorghum, and sorghum using the root analysis system, and pointed out that “To understand crop production scientifically, we must fully understand crops. Root development, root mass distribution, and root-system uptake of nutrients at different growth stages, as well as root system changes in different environments." In recent decades, researchers at home and abroad have recognized that: As the root of the underground part, it is always connected with the soil on which it depends, and it is closely linked to a root of water, fertilizer, gas, heat, and roots that are ecological to each other. Earth system."
The valve is composed of the valve head and the stem. The temperature of the valve head is very high (intake valve 570~670K, Exhaust Valve 1050~1200K), and it also withstands the pressure of gas, the force of valve spring and the inertia force of the transmission component. The lubrication and cooling conditions are poor, and the valve must be required. Has a certain strength, stiffness, heat and wear resistance. The intake valve is generally made of alloy steel (chrome steel, nickel-chromium steel), and the exhaust valve is made of heat-resistant alloy (silicon chrome steel). In order to save the heat-resistant alloy, the exhaust valve head is made of a heat-resistant alloy, and the rod portion is made of chrome steel, and then the two are welded together.
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