臭氧污染对不同品种小麦养分吸收与分配的影响

近地层臭氧(O3)污染会危害植物生长,势必间接影响氮素吸收利用.本研究利用开放式臭氧污染(Free-air O3 concentration enrichment,O3FACE)研究平台,研究了大气O3浓度增加(比周围大气高50％)对长江三角洲地区5个冬小麦(Tritcium aestivum L.)主栽品种(扬麦15、扬麦16、烟农19、扬幅麦2号和嘉兴002)的物质积累、氮素吸收与分配的影响.结果显示,O3浓度升高对秸秆和籽粒的影响远大于根系.烟农19、嘉兴002和扬麦16的产量因O3浓度升高而减少,而扬麦15和扬幅麦2号产量则变化不大.扬幅麦2号与嘉兴002的秸秆干物重因O3浓度升高而显著增加,扬麦15与烟农19分别呈增大与降低趋势,而扬麦16则无变化表明O3污染对小麦干物质积累与分配的影响存在品种差异.O3浓度升高影响氮素在小麦根、秸秆和籽粒中的含量与分配趋势,但影响程度因品种而异.O3浓度升高导致扬幅麦2号的总吸氮量显著增加30.6％及烟农19的总吸氮量呈增加趋势,并使嘉兴002的总吸氮量显著降低34.8％及扬麦16总吸氮量呈降低趋势,但扬麦15的总吸氮量则不受影响.除扬麦15外,O3浓度升高具有减少籽粒氮占总氮比例的趋势,表明小麦响应O3污染对氮素吸收与分配调整机制存在品种差异.扬麦16、烟农19和嘉兴002的氮肥偏生产力因O3浓度升高而显著降低,而扬麦15和扬幅麦2号则无明显变化.扬麦16和嘉兴002的氮肥利用率因O3浓度升高显著降低,而扬幅麦2号呈增加趋势,扬麦15、烟农19呈降低趋势.综合来看,小麦扬麦15抗O3污染能力强于其它品种,而嘉兴002则最易遭受臭氧污染危害.评价O3污染对小麦干物质与产量的形成与分配、氮素在植物-土壤系统周转的影响应综合考虑品种差异.

Effects of elevated ozone on absorption and distribution of nutrients in different cultivars of wheat

Tropospheric ozone (O₃) pollution harms plant growth, which indirectly influences absorption and utilization of nitrogen.Effects of elevated atmospheric ozone (pO₃) (50% higher than the ambient pO₃) on the biomass and nitrogen uptake and distribution of five modern cultivars of wheat (Tritcium aestivum L.cv.Yangmai 15 (Y15), Yangmai 16 (Y16), Yannong 19 (YN19), Yangfumai 2 (YF2) and Jiaxing 002 (JX002) ) were investigated in fully open-air field conditions in Yangtze River delta.Results showed that straw and grain responded to elevated pO₃ more significantly than root.The yield of YN19, JX002 and Y16 decreased, while that of Y15 and YF2 did not show any change in elevated pO₃.Elevated pO₃ significantly increased the straw biomass of YF2 and JX002 while it had no effect on Y16 and Y15; increasing and decreasing trends in Y15 and YN19, respectively, were also observed.In summary, the response of accumulation and distribution of dry matter to pO₃ pollution differed within cultivars.Meanwhile, the N content and distribution were altered by elevated pO₃ and the responses also varied among cultivars.The total amount of nitrogen uptake in YF2 significantly increased by 30.6% and the positive effect of elevated pO₃ also existed in YN19.Elevated pO₃ significantly decreased the total nitrogen accumulation in JX002 by 34.8% and a decreasing trend was observed in Y16, but not in Y15.Except Y15, all the other cultivars showed a decreasing trend in the proportion of nitrogen accumulation in grain with respect to that in total plant.Elevated pO₃ remarkably decreased the partial productivity of nitrogen fertilizer in Y16, YN19 and JX002, but had no significant effect on Y15 and YF2.Compared to ambient pO₃, the utilization efficiency of fertilizer nitrogen significantly decreased in Y16 and JX002, and slightly increased and decreased in YF2 and in Y15 and YN19, respectively, under elevated pO₃.It is concluded that wheat Y15 had the largest potential to resist O₃ pollution and wheat JX002 was the most sensitive cultivar towards O₃ pollution.Therefore, differences between cultivars should be taken into account to better understand the O₃ effects involved in the formation and distribution of dry matter and nitrogen turnover in plant-soil system.