水稻气孔臭氧通量拟合及通量与产量关系的比较分析

利用田间原位开顶式熏气装置（Open-Top Chambers,OTCs）,研究了5种不同浓度臭氧（O3）处理下（自然大气处理,AA;箱内大气处理,NF;箱内低浓度O3处理,NF＋30nL·L-1;箱内中等浓度O3处理,NF＋60nL·L-1;箱内高浓度O3处理,NF＋90nL·L-1）我国珠三角地区水稻产量损失与累积气孔O3通量（AFstX）和累积O3浓度（AOT40和SUM06）的关系,同时利用边界线拟合法,分析了不同环境因子作用下水稻剑叶气孔导度的变化特征。结果表明：水稻气孔运动的光饱和点和最适温度分别约为500μmol·m-2·s-1和33.1℃,水汽压差、物候期和O3暴露剂量的气孔限制临界值分别约为1.3kPa、500℃·d和5μL·L-1·h,高于此临界值时,气孔导度会明显下降。利用Jarvis气孔导度模型对水稻剑叶气孔导度和气孔O3吸收通量进行了预测,结果表明Jarvis模型解释了水稻实测气孔导度61%的变异性。O3吸收速率临界值（X）为2nmol·m-2·s-1时,累积气孔O3吸收量（AFst2）与水稻产量的相关性最高（R2=0.63）,明显高于O3浓度指标（AOT40和SUM06）与水稻产量的相关性（R2值分别为0.49和0.51）,表明基于气孔通量的O3风险评价指标能更好地反映水稻产量的变化。

Stomatal Ozone Uptake Modeling and Comparative Analysis of Flux-response Relationships of Rice

An open-top chambers（OTCs） experiment on field-grown rice（Oryza sativa L.） was conducted in order to compare the performance of flux-based index（AFstX） and exposure-based indices（AOT40 and SUM06） in predicting the yield loss of ozone-stressed rice. Five different treatments of ozone（O3）（Ambient air, AA;Non-filtered air, NF; Non-filtered air with additional O3 of 30 nL·L-1, NF＋30; Non-filtered air with additional O3 of 60 nL·L-1, NF＋60; and Non-filtered air with additional O3 of 90 nL·L-1, NF＋90） were adopted. Based on the boundary-line analysis, the limiting effects of environmental variables on stomatal conductance（gs） of rice flag leaves were analyzed. A typical light response curve was found for gs with light saturation at approximately 500 μmol·m-2·s-1 photosynthetically active radiation（PAR）. The optimum air temperature（T） for gs was 33.1 ℃. The critical values for gs responses to vapor pressure deficit（VPD）, phenology（phen） and O3 dose（AOT0） were 1.3 kPa, 500 ℃·d and 5 μL·L-1·h, respectively, and gs decreased sharply when the critical values were exceeded. A Jarvis type multiplicative model was drawn up and parameterized to predict gs and stomatal O3 uptake of rice flag leaves from environmental variables（PAR, T, VPD, phen and AOT0）. Approximately 61% variation of measured gs could be accounted for by the Jarvis type model. The relationship between relative yield loss and accumulated stomatal O3 uptake（AFstX）, using a threshold（X） for the O3 uptake rate of 2 nmol·m-2·s-1, provided a higher R2-value（0.63） than those of relationships based on AFstX with other thresholds（0.63）, AOT40（0.49）and SUM06（0.51）. Compared to exposure-based indices（AOT40 and SUM06）, flux-based index（AFst X） was more robust for the risk assessment of O3 on rice production in our experiment.