【摘要】 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。更多还原

【Abstract】 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.更多还原