Iron is related to hemoglobin in plants and iron is involved in the composition of some oxidases and non-haemoglobins. Iron can undergo the reversible transformation of trivalent and divalent ion states, and is therefore an extremely important participant in all redox processes in plants. It plays an electron-transmitting role in respiration and reduces the iron-chlorophyll respiration. Iron has a low fluidity in plants, and iron deficiency first appears on the upper leaves. The factors affecting the availability of iron: the more alkaline the soil is, only 7). The stronger the iron binds to the negative ions in the soil, the lower the solubility of iron. The hydrolysis of calcium carbonate in the soil, on the one hand, increases the pH of the soil, and on the other hand makes the iron and carbonate compounds more difficult to dissolve, reducing the activity of iron. The higher the content of clay (grain diameter less than 0.01 mm) in soil, the lower the effectiveness of iron. If the soil water saturation is too high, the voids between soil particles are filled with water to create a reducing environment. If the soil calcium carbonate content is high under reducing conditions, iron will form insoluble compounds. Soil organic matter has a significant role in promoting the activation of iron, and soil with high organic matter content also has a high content of available iron. Iron deficiency: When the iron deficiency of vegetables occurs, the chlorosis between young veins is pale yellow to yellow-white, and the fine reticular veins remain green. When the iron deficiency is severe, the veins will also be yellow. Control measures: Apply ferrous sulfate 3-5 kg/mu. When there is a deficiency in vegetables, spray ferrous sulfate or 1% - 2% ferric chloride solution, spray once every 5-7 days, spray 2-3 times. When the soil is strongly alkaline, 2-3 kilograms of sulphur powder can be used in mu. Portable Cable Reel,Garden Water Hose Reel,Retractable Garden Hose Reel,Wall Mounted Garden Hose Reel NINGBO QIKAI ENVIRONMENTAL TECHNOLOGY CO.,LTD , https://www.water-hose-reel.com