Cotton deficiency

Symptoms: 1. Nitrogen-deficient and nitrogen-deficient cotton plants grow slowly, the stems are short and thin, and the proportion of red stems is increased. Woody branches and axillary buds are rarely formed; the old leaves are uniformly yellowish-green and fade into yellow, and then become yellow-brown when severe. Withered; fruit branches do not stretch out, generally only one fruit section, Lei Ling bell shedding more, low yield. 2. Phosphorus deficient Phosphorus-deficient cotton plants grow slowly and are dwarf. The stalks are slender and brittle. The leaves are dark green or gray-green, lack luster, and the leaves become smaller. In severe cases, grey stems appear from the tip of the leaves along the leaf margins, and are purplish. Also turned purple. Lei, blooming, bolling delay. Third, the most typical symptoms of potassium deficiency are yellow-white patches on the leaves. Then yellow spots appear between the veins and gradually expand into brown spots. Finally, the whole city is reddish-brown, and the leaves are easily dehydrated and shrunken, and the leaf margins are drooping. Dead or early fall off; stalks are small and weak, and the bells of the larvae fall off. The bells are small and it is difficult to spit; the plants that are short of potassium are dead prematurely and they appear as "dry leaves withered stems." IV. Boron-deficient growth point necrosis, stop growth, only leaf buds grow, plant clusters, dwarfs and more branches, leaves curling in reverse, leaf thickness uneven, petiole ring protrusion; eventually lead to "bud without flower "Or "flower without bell", severely reduced production. 5. The period of zinc deficiency was significantly shortened, the plants were short, the leaves became green and yellow, and the buds and bells were severely shed. The growth period was significantly delayed. Sixth, magnesium-growth-cotton strains grow slowly, yellow leaves and red leaves appear in the local leaves, leaf chlorosis, leaf veins with gray-green necrotic spots. Seven, iron-deficient cotton chlorosis often occurs after chlorosis, and from the young leaves began to yellow and white, the old leaves remain green, when the whole leaf is yellow and brown withered. VIII, calcium deficiency growth point necrosis, leaves yellowing green, but the veins remain green, stems and leaves weak, yellow scorch. Nine, deficiencies of young leaves lost chlorosis, yellow-gray to red-gray plaques between veins, veins remain green. Tenth, lack of molybdenum at the tip of the leaves of the leaf veins appear chlorosis, Lei Ling fall off. 11. Sulfur-tolerant cotton plants will turn pale green to yellow. At the same time, the plants will be shorter. The leaves will turn yellow, but they will have obvious green veins.

Cause of a lack of nitrogen Fertility or soil cotton plants, if not the appropriate amount of nitrogen fertilizer and rhizobial inoculation susceptible to nitrogen deficiency symptoms. Phosphorus deficiency in the majority of the two most common soil phosphorus, under normal circumstances, the need for the application of different amounts of phosphate fertilizer, otherwise there will be different levels of phosphorus deficiency symptoms. Potassium deficiency is prone to potassium deficiency in acidic soil, sand, and some high-yield areas where nitrogen fertilizers are used in the south of China. In recent years, the level of nitrogen applied in production has been increasing year by year, and the application of potash fertilizer has been relatively small. Especially in sandy cotton fields where continuous cropping is done for many years, the lack of potassium in soil is more prominent. The boron-deficient boron cotton has obvious symptoms of boron deficiency. Boron can be fixed in the soil by aluminum, silicon and some clay minerals, and this fixing effect rapidly increases with increasing pH. Therefore, the soil developed from acid igneous rocks is prone to boron deficiency. . Five deficient zinc, manganese high pH calcareous soil, especially in these soils after the formation of exposed soil and soil, more likely to zinc, manganese. The cotton planting in Jianghan Plain and Weibei area in China should pay attention to preventing zinc and manganese deficiency. Six Mg-deficient Mg-planted cotton in soils with a large amount of potassium fertilizer is prone to symptoms of magnesium deficiency. Seven Calcium Deficiency Calcium is prone to be present in soils developed in certain granite or slate in southern China. Eight shortages of molybdenum acid soils are susceptible to molybdenum deficiency. Sulfur deficiency may occur in cotton grown on certain soils in the southern mountainous areas and semi-mountainous regions.

Control methods to prevent cotton deficiency, first of all to determine the content of relevant nutrients in the soil, clarify the causes of the local lack of nutrients, combined with the characteristics of local fertilization, cotton growth conditions and related conditions, so that scientific and rational application of base fertilizer or top dressing. The input ratio of nitrogen, phosphorus and potassium in most cotton areas in China is suitable for 1:0.3:0.8-0.9. (1) Prevent nitrogen deficiency on the basis of the application of decomposed organic fertilizer, use 7-8 kg of urea, 15-20 kg of ammonium bicarbonate or 500-750 kg of human waste per 667 m2; 1% to 2% of urea Liquid spraying. (2) To prevent phosphorus deficiency, apply 25-30kg of superphosphate per 667m2 to water attack or use potassium dihydrogen phosphate 150-200g, water 75-100kg, or foliar application of potassium dihydrogen phosphate 150-200g, water 60kg. Spray 2-3 times. (4) To prevent boron deficiency, add borax 150-200g per 667m2 with nitrogen, phosphorus, potassium and other fertilizers to top up the water, or use 50-100g of borax to spray 50-60kg of water. (5) To prevent zinc deficiency, apply 1-1.5 kg of zinc sulfate per 667m2 to water, or 50-70g of zinc sulfate to 50-75L of water per 667m2 of foliar spray. (6) Prevent magnesium deficiency from spraying with 061-062% magnesium sulfate solution and spray twice consecutively. (7) Prevent iron-deficient cotton fields from spraying with 0.3% ferrous sulfate solution. (8) Prevent calcium deficiency and spread lime 50-75kg per 667m2. (9) To prevent the lack of molybdenum and molybdenum in the acidic soil can be corrected by the use of lime to improve the effectiveness of the original molybdenum in the soil to correct the symptoms of molybdenum deficiency.