Photochemical Oxidants Injury in Rice Plants : III. Effect of ozone on physiological activities in rice plants

[摘要] The experiments were made to determine the effect of photochemical oxidants on physiological activitics of rice plants. Rice plants were fumigated with ozone at concentration of 0.12-0.20 ppm for 2-3 hr to investigate the accute injury and at 0.05 and 0.09 ppm for daily exposure from 3.0 leaf stage to assess the effect of ozone on growth. 1. It was observed that malondialdehyde produced by disruption of the components of membrane increased in the leaves exposed to ozone. 2. Ozone reduced the RuBP-carboxylase activity in both of young and old leaves 12-24 hr after fumigation and then in the young leaves the activity of this enzyme recovered to some extent after 48 hr, but it did not show any recovery in the old leaves. On the otherhand, ozone remarkably increased the peroxidase activity and slightly increased acid phosphatase in any leaves. 3. Abnormally high ethylene evolution and oxygen uptake were detected in leaves soon after ozone fumigation. 4. In general, high molecular protein and chlorophyll contents in the detached leaves decreased with incubation in dark, particularly in the old ones. These phenomena were more accelerated by ozone fumigation. Kinetin and benzimidazole showed significant effect on chlorophyll retention in ozone-exposed leaves. 5. Reduction of plant growth and photosynthetic rate was recognized even low concentration of ozone in daily exposure at 0.05 and 0.09 ppm. From these results it was postulated that ozone may act the senescence of leaves in rice plants.

[学科分类] 农业科学（综合）