[Effects of ozone pollution on the accumulation and distribution of dry matter and biomass carbon of different varieties of wheat].

Effects of surface ozone pollution on the terrestrial ecosystem and plant growth have drawn great attention. With the support of the free-air ozone concentration enrichment (O3-FACE) system located in Jiangdu City, Jiangsu Province, the effects of elevated atmospheric ozone (pO3) on the accumulation and distribution of dry matter and biomass carbon as well as the C/N ratio of crop residue of five wheat (Tritcium aestivum L.) varieties (Yangmai 15, Yangmai 16, Yannong 19, Yangfumai 2 and Jiaxing 002) were investigated in the Yangtze River delta, the target pO3 of which was 50% higher than the ambient pO3. The results showed that the accumulation and distribution of different wheat varieties responded differently to elevated pO3. Elevated pO3 decreased the biomass of Yangmai 15 and Jiaxing 002, increased the Yangfumai 2 biomass, and had no effects on the total biomass of Yangmai 16 and Yannog 19, among which a significant difference was found for Jiaxing 002. Elevated pO3 significantly increased the ratios of root to shoot for Yangmai 15 and Jiaxing 002 and significantly decreased the root/shoot ratios of Yannong 19 and Yangfumai 2, but had no effect on Yangmai 16, leading to an obvious difference in dry matter distributed among aboveground and belowground parts. O3 enrichment decreased the wheatear weight of Yangmai 15, Yangmai 16 and Jiaxing 002, and had no effect on that of Yannong 19 and Yangfumai 2. Elevated pO3 significantly decreased the proportion of grain weight to ear weight by 8.2%-15.5% for Jiaxing 002, Yannong 19 and Yangfumai 2, whereas the proportion was increased for Yangmai 15 and not affected for Yangmai 16, suggesting that O3 enrichment lead to different decreases in the yield of Jiaxing 002, Yannong 19, Yangfumai 2 and Yangmai 16. Elevated pO3 significantly increased the straw carbon of Yannong 19 and Yanfumai 2 by 14.1%-22.9% and significantly decreased the straw C/N ratio by 10.9%-29.1%. The rising pO3 significantly decreased the straw carbon of Jiaxing 002 and significantly increased the straw C/N ratio. Moreover, for Yangmai 16 and Yangmai 15, there was a decreasing straw carbon amount and an increasing straw C/N under rising pO3. Elevated pO3 significantly decreased the carbon quantity and C/N of root residue in Yangmai 16, Yannong 19 and Yangfumai 2. Elevated pO3 had not significant effect on the root residue carbon of Jiaxing 002, but significantly decreased its C/N ratio. However, elevated pO3 had no effect on the quantity and quality of the root residue of Yangmai 15. It is obvious that when evaluating the response of the formation and distribution of wheat dry matter and the quantity and quality of root and straw carbon to O3 pollution, the difference in wheat varieties should be taken into account.