缺氮玉米:叶黄色,老叶尖端干枯,沿叶脉向里延伸,茎细瘦。棉花:下部叶子变黄枯干,整株淡绿,植株细弱,分枝少。小麦:叶黄绿,尖端变黄,分麋少,茎细弱发红。苹果:叶小淡绿,老叶枯黄,红或紫色,早落。叶柄与枝条的夹角小,枝棕红色,细弱。花芽少,果小。西红柿:叶浅绿,下部叶变黄干枯。叶脉深紫,茎硬呈紫色,花蕾黄落。 Nitrogen-deficient corn: yellow leaves, dry tip of old leaves, extending inwardly along the veins, stem thin. Cotton: the lower part of the leaves turn yellow, the whole plant light green, thin plants, less branches. Wheat: yellowish green leaves, sharp yellowing, less elk, thin stem redness. Apple: small green leaves, old leaves yellow, red or purple, early fall. The angle between the petiole and the branches is small, branches reddish brown, delicate. Flower bud less fruit small. Tomatoes: light green leaves, the lower leaves turn yellow dry. Violet vein dark purple stems, yellow buds.