Studies on wetting injury of crop plant by rainfall.

1.对降雨后植物叶片的萎萎和伤害进行了观察。叶片中的结构增加，蒸腾作用大大增加。蒸腾作用的增加破坏了根吸收和叶损失之间的水分平衡，叶片出现水分亏缺，导致叶片枯萎。降雨对菜豆第1、2叶造成伤害。降雨暴露1-2天仅造成轻微损伤，而暴露3天或更长时间则有显著影响。叶片组织发生坏死，出现断边叶、坏死斑、心形叶、皱纹叶等症状。枯萎伤病的严重程度可能与叶片的拒水性、水接触角、叶片表面蜡质和叶片含糖量的变化有关。测定了冈山仓城县和香川县三木县雨水的pH值和EC。1988年-的年均pH值冈山为4.3，香川为4.6。

1. Wilting and injury of plant leaves were examined after rainfall. The structure in leaf is increased, so that transpiration is increased greatly. The increase of transpiration destroyed the water balance between uptake by root and loss from leaf, and a water deficit occurred in leaf, resulting in the wilting of the leaves. Exposure to rainfall caused injury of the 1st and 2nd foliage leaves of kidney bean. Exposure to rainfall for 1-2 days caused only slight injury, but the exposure for 3 days or more had a marked effect. Various symptoms, such as edge break leaf, necrotic spot leaf, cordate leaf and rugose leaf, appeared as a result of the necrosis of leaf tissue.2. Degree of the wilting and injury may be attributed to differences in water- repellency, contact angle of water, superficial wax on leaves and change of sugar content in leaves.3. pH and EC of rain water at Kurashiki, Okayama and Miki, Kagawa were measured. Annual average pH values in 1988-1989 were 4.3 at Okayama and 4.6 at Kagawa.