Nitrogen deficiency yellowness. The nitrogen deficiency of rice seedlings is generally uniformly yellowed from the old leaves and gradually spread from the base leaves to the core leaves. Finally, the whole plant is yellow, the rice seedlings are short, the leafhoppers are different, the tillers are late and thin, and the leaves are short, narrow, and upright. Yellowish green, resulting in plant dwarfism, fewer tillers, premature aging, small ears, grain is not full. Remedy: At this time should be added nitrogen fertilizer, urea per acre 5 to 7 kg, if the lack of nitrogen is serious, should slightly increase the amount of application, with the application of phosphorus, potassium fertilizer, applied after cultivator, to promote the conversion of yellow seedlings.
Phosphorus deficiency. After the early rice seedlings turn green, their growth is significantly slower, and the tillers delay or not give birth, or they show symptoms of stiff seedlings after turning green. The leaves are thin and erect, and when they are severe, the leaves are curled and folded along the midrib, and the leaves are dark green and dull. Blue-purple, distant view of the rice plant dark green with gray-purple; rice plants were clustered, short and thin; roots tightened, new roots rarely, and sometimes the complications of hydrogen sulfide poisoning. P-deficient rice often appears premature. Remedial measures: Top-dressing with shallow water, 30-kg superphosphate and 25-30 kg per acre of mixed ammonium bicarbonate, along with mixing and application, immediately after cultivation, cultivating or using 0.2% potassium dihydrogen phosphate solution, fertilizer solution prepared per acre 50 ~ 60 kg spray. In the water management, shallow irrigation was conducted and the field was repeatedly exposed to increase the soil temperature and enhance the ability of rice roots to absorb and metabolize phosphorus. When the new roots were born, the cultivation of urea was promoted by 3 to 4 kilograms per mu.
Deficiency potassium. Early rice lack of potassium, although rooting back to green after transplanting, but the leaves were brown with brown spots, the old leaf tip, the edge of the red-brown small spots, and finally the blade gradually turned brown from the tip down withered. Each time a new leaf grows, it will increase the lesions of one old leaf. In serious cases, only a few new leaves will remain green and look like a fire. The peasants vividly say, "A far-sighted red, close-looking, and no insects. ". The whole root system of the diseased plant was yellow-brown to dark brown with few new roots. Potassium aceti deficiency mainly occurs in cold paddy field, rust paddy field and muddy field in early rice. Remedial measures: Immediately drain water, apply 100-150 kilograms of wood ash per acre, or apply 4-6 kilograms of potassium chloride per acre. Before fertilizing, put dry field water, apply a strip or a hole, apply 5-10 centimeters deep into the soil. . Or foliar spray 1% potassium chloride or potassium sulfate solution. With nitrogen fertilization, interstitial irrigation, promote Wangfa, increase absorption capacity.
Zinc deficiency cluster disease. The zinc-deficient early-season rice seedlings first appeared in the middle lobe of the lower lobe with chlorosis, whiteness and erythematous spots, irregular spots, and reddish-brown spots. They gradually expanded to reddish-brown streaks and turned reddish-brown to dry from the tips of the leaves. The next up and down leaves appear one by one. The leaf speed of the diseased plant was slowed down, the new leaf was short and narrow, and the new leaf was faint, especially yellowish-white fading near the midrib of the base. Severely ill plant leaf spacing shortened or misaligned, obvious dwarf clumping, leaf sheath longer than the leaves, jointing difficulties, loose and loose tillers were tussock-like, delayed maturity, although the extraction of slender panicles, mostly can not be strong. Remedial measures: Immediately drain open fields, increase oxygen ventilation, and promote root development. When the rice seedlings show symptoms of zinc deficiency, the zinc sulphate is formulated into a 0.1% to 0.2% aqueous solution for foliar application. The prepared zinc sulphate fertilizer solution is 50-60 kg per mu and sprayed once every 7 days. , You can spray it twice.
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