In order to make clear the mechanism of reduction of water-content in rice plants by wind, we have studied on the water-contents of them.
Results are as follows:
(1) The water-contents in each organ of the rice plant grown under normal condition increased in order of ear, leaf and stem, and their variances decreased in the same order.
(2) When the water supply from root was intercepted, the plants began to wilt. However, younger leaves showed a small decrease in the water-content, and had a large resistance against dehydration. Because the wilting occurs by a slight decrease in water-content, it is difficult to measure the decrease at the beginning of wilting.
The reduction of water-content in the ear was smaller than that in the leaves, but it fluctuated by number of days after heading.
The reduction of water-content was smallest in the stem.
(3) The critical water-content for the recovery from wilting was different by the stage of growth of rice plants. Before milky ripe period it was about 50 per cent, and about 60 per cecnt in waxy ripe period.
(4) The reduction of water-contents in each organ of rice plants treated by wind have been observed.
In a leaf, the reduction of water-content was considerably large in the upper half part of leaf blade No differences in the reduction of water-content were recognized between the sites of leaves. The differences of water-content between the ears of treated and untreated were not clear in the present experiment.
The reduction of water-content in the stem was smallest, but when the stem have had a young head before heading it was considerably large.
Under the condition of stronger wind and of longer duration of treatment, the reduction of water-conteant was more remarkable.