亚热带地区水稻(Oryza sativa L.)气孔臭氧通量和产量的响应关系

基于开放式臭氧浓度升高O_3-FACE(Free-Air Concentration Elevation of O_3)实验平台,利用前期水稻O_3-FACE试验的基础数据,通过建立水稻产量与不同评价指标(累积气孔O_3吸收通量PODY和O_3浓度指标AOTX)的响应关系,比较了水稻产量损失与各评价指标的相关性差异,通过对暴露剂量、吸收通量相关参数取值与产量损失的观察和分析结果的比较,找出更为合理的农作物臭氧风险评估阈值。结果表明:随着通量阈值Y0~11 nmol O_3·m~(-2)PLA·s~(-1)(PLA:projected leaf area,投影叶面积)]和暴露浓度阈值X(0~50 n L·L~(-1))的增加,回归分析R~2值逐渐增加,当Y为11 nmol O_3m~(-2)PLA·s~(-1)和X为50 n L·L~(-1)时,气孔臭氧吸收通量POD11和累积暴露剂量AOT50与水稻相对产量的相关性最大,当通量阈值Y为8~13 nmol O_3·m~(-2)PLA·s~(-1)和暴露阈值X为46~58 n L·L~(-1)时,可获得较高的R~2值取值范围,分别为0.70~0.75和0.70~0.745。参考文献发现,目前地表臭氧污染可能引起的水稻产量损失范围为5%~8%,对照圈中POD9~10和AOT40~45产量损失的预测值亦在这区间,但前者R~2值(0.73~0.74)明显高于后者R~2值(0.64~0.69),表明基于气孔臭氧通量的评价指标能更好地反映水稻产量的变化。通过进一步分析发现,当通量阈值Y为9 nmol O_3·m~(-2)PLA·s~(-1)时,能更准确地评估水稻产量损失,且其R~2值(0.73)高于通量指标POD6(0.57)。以上研究结果表明,通量指标POD9更适合评估亚热带地区O_3污染对水稻作物的影响。

Stomatal ozone flux-response relationships of rice(Oryza sativa L.) in subtropical area

Based on previous investigations on a fully open-air ozone(O₃) fumigation experiment(O₃-FACE), we established dose-response relationships using O₃ dose index AOT40(accumulated O₃] above 40 nL·L^-1) and POD_Y(phytotoxic O₃ dose, accumulated stomatal flux of O₃ above a threshold of Y nmol·m^-2·s^-1), and compared their performance on O₃-induced rice yield loss evaluation. The aim of this study is to find the optimum threshold for exposure-based and flux-based dose-response relationships used for ozone risk assessment on rice. Our result showed that the R²-value of regression analysis increased with flux threshold Y0~11 nmol O₃·m^-2 PLA·s^-1(PLA:projected leaf area)] and exposure threshold X(0~50 nL·L^-1) increase, respectively. When flux threshold Y was 11 nmol O₃·m^-2 PLA·s^-1 and exposure threshold X was 50 nL·L^-1, the O₃ dose index POD₁₁ and AOT50 had the strongest correlation with RY(relative yield) of rice, respectively. High R²-value was derived i.e. 0.70~0.75 and 0.70~0.745 when flux threshold Y was within the range of 8~13 nmol O₃·m^-2 PLA·s^-1 and exposure threshold X was 46~58 nL·L^-1, respectively. Previous studies have indicated that the rice yield loss caused by near-surface ozone pollution may range from 5% to 8%. These results were similar with our estimation on ambientO₃] treatment using POD_9~10 and AOT40~45. The higher R²-value 0.73~0.74 with POD_9~10 compared to that of 0.64~0.69 with AOT40~45 indicated that flux-based assessment may have a superior performance on O₃-induced rice yield loss estimation. Further analysis found that when flux threshold Y=9 nmol O₃·m^-2 PLA·s^-1, assessment of rice yield loss was more accurate, and the R²-value(0.73) was higher than that of POD₆(0.57). Our results suggested that POD₉ is suitable for evaluating rice yield loss due to O₃ increase in subtropical area.