| Research Abstract |
1. The studies were designed to obtain the information on the changes of structure and wettability of leaf surface by wetting of rain water.
(1)Leaf wettability of 17 plant species by wetting of rainfall was examined. Considerable differences were observed among the plant species. Retention of water drops on leaf surface was 10mg/cm^2 or more in rice, tomato, cucumber, radish spinach, etc., and 5mg/cm^2 or less in cabage, welsh onion. (2)The wettability was higher in adult leaves than that of young active leaves. (3)The superficial waxes of leaves were closely related to the wettability, and decreased a markedly by the exposure of rainfall. (4)Leaves of various plants detached after wetting of rainfall for 3 days or more had a higher drying rate than that of non-wetted leaves. (5)The contact angles of water drops on leaves were closely related to the wettability of leaves. (6)The wetting of leaves may be attributed to differences in plant species, leaf age, leaf wax, contact angle of water drops.
2. pH of rainfall at Kurashiki was measured for 4 years(1988-1991). Acid rain which had a pH value lower than 5.6, was observed on 94% of 'the total samples(208 rainfall events). When the yellow sand came fly from China continent, the pH values of rain water was 7.0 or so.
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