The Impacts And Defence Of O₃ On Crop In Site

With the swift development of industrialization and urbanlization, increasing of the tropospheric O₃ concentration at a striking rate, O₃ pollution induced more important effects on crop and the ecological environment.It is considered that O₃ pollution is a one of the most serious air pollution and has become a more attention problem for in vestigators in the world at present.It is studied hotly by ecology and environment science,but the study on the impacts of O₃ concentration change on crop has been most use of the stimulation-method of high concentration and short time fumigation. This paper was first time to study systematically the impacts of different level of O₃ concentration on winter wheat,spinach,rice in the area of Yangtze River and Zhujiang Delta by using open-top chamber ( OTCs) and researched the effects of extra-ascorbate on the rice which had been intimidated by O₃. This paper provided important parameters for exploring deeply and avoiding the air pollution and theoretical evidence for instructing agricultural production and ensuring food supply.The main conclusions were listed below:1.The elevated O₃ exposure resulted in typical visible foliar injury sympotoms such as small lightgreen,brown necrotic flecks,dry necrotis and so on. With the O₃ concentration enrichment, the leaf senescence was accelerated,the sensibility intimidated by environment was increased, the growth was restrained and the yield was decreased.2.With the increasing of O₃ concentration,the growth duration was shortened.the prophase growth was impacted less,but the anaphase growth ,especially unsheathing spike stage,was shorted seriously. anthsis stage and milk stage of rice were shorted, the grain weight and quality were affected seriously,the plant became shorter, leaf areas and biomass were decreased,the distribution of dry matter was changed, special leaf area was increased relatively,the difference of relative growth rate and net assimilation rate were greater during prophase growth,the ratio of grain weight and leaf area and the ratio of grain quantity and leaf area were change following the change of O₃ concentration.3.Being treated by extra-ascorbate, the growth indicators of the rice were changed,such as the ramification differentiation,the ratio of fertile floret and the accumulate of dry matter were elevated obviously .The harvest index can also be increased.4.The gas exchanging parameters showed that the Pn,Gs,Tr of rice were descented under intimidated by O₃.The Pn of different treatment were trended to ascent and the Gs...