Lotus root, particularly shallow water lotus grown for many years, since the long-term flooding soil, poor permeability conditions, soil, iron, zinc, copper and other trace elements difficult to meet the growth of shallow water lotus, exhibited a slow growth, "lotus leaf is Gypsophila no closure line ", a lack of fertilizer symptoms, if not symptomatic fertilizer, serious cuts will occur, causing large economic losses.
Nitrogen deficiency lotus leaf color yellow, small, thin blade, lotus short petioles, elongated rhizome. Adding 100 kg of ammonium bicarbonate per acre, or 35 kg of urea, can quickly enhance the photosynthesis of lotus leaf growth, which is conducive to the formation and accumulation of protein and various Vitamins in lotus root plants, and increase the yield of lotus root production. However, if the nitrogen is applied too much, the lotus leaves will be green, the petiole will be slender, the pests will be harmful, and the lotus root yield will not be high.
The leaves of the phosphorus-deficient lotus leaves are small, dark green and dull, and the lotus whip is slender and yellowish brown, with more black roots and less white roots. This is due to insufficient supply of phosphoric acid, and the reduction process of nitrate nitrogen in crops is hindered, affecting protein synthesis and inhibiting cell division. Applying 100 kg of superphosphate to increase the number of white roots, the lotus roots are slender and thick, and the loss of phosphorus in the early stage of lotus root growth is restored, which promotes the accumulation of starch in the late growth stage of lotus roots, the increase of branches, the increase of main tendons, and the improvement of lotus roots. Yield. However, excessive application of phosphate fertilizer, imbalance of nitrogen and phosphorus ratio, shortening of vegetative growth period, it is also difficult to obtain high yield of lotus root; in addition, in areas where soil zinc deficiency occurs, excessive application of phosphate fertilizer often causes the loss of trace element zinc in lotus root growth.
Part of the zinc-deficient lotus leaf is chlorotic, showing flaky or irregular pale yellow plaques. Only about 3 kg of zinc sulphate per acre can promote the stable yield and high yield of lotus root.
The potassium-deficient old leaves are yellow-green-like watermelon-like stains, and the petiole is slender and easy to fall. Increasing the application of 30 kg of potassium chloride can promote the metabolism and synthesis of nitrogen and carbohydrates in lotus root plants, facilitate protein synthesis, promote the synthesis of stem and leaf cellulose and the development of vascular bundles. Thick, enhance the lotus root resistance to disease, improve the appearance quality and yield of lotus root. However, excessive application of potassium fertilizer, its excessive cellulose content also affects the edible value of lotus root commodity, and the food is poor.
When the iron deficiency occurs at the beginning of the growth peak from July to August, the fresh leaves just appear to be slightly wilting when they emerge from the water surface. The veins gradually lose green and light, and there are brown spots on the edge of the leaves and gradually enlarge until the whole leaves die, but the underground stems are free of symptoms. . In order to prevent the occurrence of iron deficiency symptoms, organic fertilizer should be added during planting, and the amount of nitrogen fertilizer should be properly controlled. When there is only a thin layer of water in the lotus field, 2 to 2.5 kg of ferrous sulfate per acre, 25 to 30 kg of calcium, magnesium and phosphate, and 40 kg of dry fine soil. Or in the middle and middle stages of growth, use 150-200 ml of Huimanfeng per acre and spray 1~2 times with 30 kg of foliar water.
The boron deficiency lotus root is deficient in boron, the leaves are still green, but the veins turn yellow and the leaves are small. When the boron is severely deficient, the veins are especially the main veins, the bulges are raised, the texture is hard and brittle, the stems turn yellow and crisp in advance, the underground stems become small and hard, and the expansion speed is slow. For example, if only the nitrogen fertilizer is applied to the bottom fertilizer, and the boron fertilizer is not applied, the boron fertilizer should be applied in time from the end of June to the beginning of July. The amount of boron fertilizer applied: 1~1.2 kg per mu for severe boron deficiency; 0.8~1 kg for medium boron deficiency; 0.5~0.7 kg for slight boron deficiency. Add 10 kg of dry fine soil or dry fine sand according to the amount of borax. Mix well and enter the field from the walking line. After the application, mix the topsoil with borax in a long time and then keep the shallow water until the drainage period before the excavation. However, the amount of boron fertilizer is not as good as possible. The application rate per mu should be strictly controlled at 0.5~1.2 kg. If it exceeds 2 kg, the symptoms of boron poisoning will occur, and the yield will be significantly reduced. The period of boron fertilizer application should not exceed the first half of July, otherwise the effect will not be significant.
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