一、缺氮症状苗期缺氮,幼苗生长缓慢,植株矮小细弱,叶色变黄;三叶期缺氮叶鞘呈紫红色,并沿叶脉向下扩展;以后最明显的症状是由叶尖开始变黄,再沿叶脉呈楔形向基部扩展,最后整个叶片枯黄衰亡;穗小头部不饱满。发生条件前茬未施有机肥或耗肥较大;一次性施肥,降雨多,氮被淋失。矫 First, the nitrogen deficiency Symptoms of nitrogen deficiency, seedling growth is slow, plant dwarf weak, yellow leaves; triloba nitrogen-deficient leaf sheath was purple, and down along the veins down; after the most obvious symptoms from the leaf tip Yellowing, and then along the vein was wedge-shaped base to expand, and finally the entire leaves yellow brown decay; spikelets head is not full. Occurred before the crop did not apply organic fertilizer or larger fertilizer consumption; one-time fertilization, rainfall, nitrogen was leaching. Correction