湿黄由于土壤水分过多引起的,造成土壤缺氧,使根部呼吸困难,根系吸水、吸肥受阻,生长不能正常进行而导致幼苗新枝顶叶淡黄色,老叶也渐暗黄,进而枯萎死亡。此时,应及时松土、排水,控制灌溉量。旱黄干旱会使幼苗出现萎蔫现象。此时的光合作用下降,生长停顿,光合产物的运输因缺水受阻,植物体内有机物大量水解,呼吸增强,从而消耗大量有机物。由于植物体内水分重新分配,新叶从老叶中夺取水分,造成老叶 Wet yellow due to excessive soil moisture, resulting in soil anaerobic, so that the roots of breathing difficulties, root absorption, absorption of fat blocked, the growth can not be normal led to the seedling shoots pale yellow, the old leaves also dim yellow, and then withered death . At this point, should promptly loose soil, drainage, control of irrigation. Dry drought will make young seedlings appear wilting phenomenon. Photosynthesis decline at this time, the growth of pause, obstruction of transport of photosynthetic products due to lack of water, a large number of plant organic hydrolysis, respiratory enhancement, which consume large amounts of organic matter. Due to the redistribution of water in plants, the new leaves take water from the old leaves and cause old leaves