Physiological Aspects of Tolerance to Ozone and in Relation to Ozone Absorption in Rice (Oryza sativa L.)

• Main Authors: Yang, Chang-Kuo, 楊政國
• Other Authors: Chun Chu, Huu-Sheng Lur
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/59388990102289754328

碩士 === 國立臺灣大學 === 農藝學系 === 85 === AbstractSeveral crop plants have been found to have the ability to absorb ozone, and have the potential on reducing ozone pollution. The objective of this study was to explore the relationships between rice growth and ozone in troposphere. The concentration of ozone in the air beside the Kee-Long Road along the field of The Experimental Farm Station of National Taiwan University, and control and rice field was detected. Ozone absorption rate of seedlings of selected rice cultivers were measured and compared. Ozone treatment was carried out on several rice varieties by using continuously stirred tank reactors, the tolerance, physiological responses to ozone and activities of enzymes involved in scavenge of free radical were studied. The result1. There was no difference between the ozone concentration detected in side way of Kee-Long Road along The Experimental Farm Station of National Taiwan University or measured at Ku-Ting Station of Environment Protection Administration. Ozone concentration in rice-growing field was reduced by 1 to 3 ppb from the seedling stage to the maturing stage. Ozone was absorbed mostly on the flowering stage with a amount of 9 %, suggesting that ozone in the air could be reduced by rice field. Absorption ability of ind2. Under ozone exposure, leaves of rice seedlings showed brown spots. Leaf tips became dehydration and etiolating when the rice were treated with smell gas for 24 hours. 24 rice varieties treated with ozone could be graded into five classes with respect to the injury symptom. Japonica varieties were more tolerant to ozone than indica varieties. Injury symptom in japonica varieties appeared until the ozone concentration reached 800 ppb, while the symptom in indica varieties already showed when the concentrat3. Chlorophyll and protein contents of indica rice were higher than those of japonica rice. The contents in indica rice decreased significantly by ozone treatment, and there was a negative correlation between the chlorophyll or protein content and the injury grade. Chlorophyll and protein contents in japonica varieties remained constant under ozone treatments. The leakage conductivity values of indica varieties were higher than those of japonica varieties. Indica rice showed significant injury under concent4. There were no statistical difference on leaf H2 O2 content among tested varieties. Even H2O2 content was not related with chlorophyll content, but tested varieties had high H2O2 contents under a heavier injury status. Thus, reduce the H2 O2 content in rice plant might reduce the injury caused by ozone.5. Enzyme activities of antioxidase, such as peroxidase and catalase, especially peroxidase were higher in japonica varieties. This might be correlated with the results that H2O2 content of japonica rice were much lower than that of indica rice, i.e., peroxidase within japonica could scavenge injury- produced peroxide. Although superoxide dismuctase is suggested to be one of key enzymes that could clear the peroxide free radicals in plant, but in this work, its activity decreased after ozone treatment. AscorThe results of the present research showed that japonica varieties were more tolerant to ozone than did the indica rice. This might be due to that japonica varieties have a more efficient peroxidase enzyme system, and have a lower ozone absorption ability. Rice cultivated in Taiwan are mostly japonica varieties, it is worthy of further evaluation whether there is a reduction effect of ozone at the troposphere by the whole rice field in Taiwan.