The Relationship between Environmental Factors and Behaviour of Stonlata in the Rice Plant : 2. On the diurnal movement of the stomata

Abstract

The diurnal movements of the stomata in the leaves of various developmental stages of the rice plant under various weather conditions in submerged paddy field were studied by using the infiltration method for measuring the aperture of the stomata. The course of the diurnal movement of the stomata in the leaves of the rice plant grown under submerged paddy field was much affected by weather conditions from day to day. In a sunshiny day the aperture reached the maximum at about 8.30-9.00 a.m. and then decreased very quickly to only 1/2 or less of the maximum in the afternoon. On the contrary, in a cloudy day or not so fine day the aperture increased slowly in the morning to reach the maximum at about noon and in the afternoon the aperture was still kept wide for sometime. From the tillering stage to the heading stage the maximum of the aperture per day was practically the same irrespective of the weather condition except under very low light intensity. However after the heading stage the maximum per day became less. Furthermore, after reaching the maximum per day the aperture decreased more quickly compared with those before the heading. When the aperture became small in the afternoon of a sunshiny day the stomata of the leaves in the rice plant which were covered with polyethylene bag for 20-30 minutes opened again up to near the maximum in the day. From these facts it is assumed that the cause why the aperture of the stomata decreases in the afternoon of asunshiny day or after the heading stage may be due to the water unbalance in the leaves of the rice plant grown under submerged paddy condition.