1.土壤干旱造成的弱苗多发生于底墒不足或透风跑墒的麦田,其特点是:分蘖出生慢,叶色灰绿,心叶短小,生长缓慢或停滞(群众称之为“缩心苗”),中下部叶片逐渐变黄干枯,根少而细。管理要点:结合浇水,667平方米追施碳铵15千克。2.土壤缺氮造成的弱苗幼苗细弱呈直立状,分蘖减少,叶片窄短,下部叶片从叶尖开始,逐渐变黄干枯,并向上部叶片发展。管理要点:667平方米用尿素7~8千克,或碳铵20~25千克,在行间沟施或对水浇施。 1. Weak soil caused by soil drought occur in the end of lack of soil moisture or run through the soil moisture, which is characterized by: tiller slow birth, gray-green leaves, heart short leaves, slow growth or stagnation (the masses called the “shrink heart Miao ”), the lower part of the leaves turn yellowish dry, small and thin roots. Management points: combined with watering, 667 square meters topdressing 15 kg of ammonium bicarbonate. 2. Weak seedlings infested by soil nitrogen deficiency were erect, tillers reduced, leaves short and narrow, the lower leaves began from the tip, gradually turn yellow and dry, and the development of the upper leaves. Management points: 667 square meters with urea 7 to 8 kg, or ammonium bicarbonate 20 to 25 kg, between the lines of ditch or water facilities.