Effects of elevated ozone on absorption and distribution of nutrients in different cultivars of wheat
臭氧污染对不同品种小麦养分吸收与分配的影响

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.