| As one of the most harmful air pollutants, ozone (O3) has been widely notorious for its phytotoxic effects on crops. Crop yields losses caused by elevated ozone concentration have caused widespread concern. Our studies were carried in south China region and Jingjintang area on the main food such as rice, corn, vegetables and winter wheat. Open top chambers (OTCs) under field conditions were used to investigate the visible damage, antioxidant system, membrane lipid peroxidation of the crop vane and quantities of the functional genes in the crop soil. The conclusions were as followed in this research.1、O3stress can result in crop injury symptoms obviously, and symptoms become more serious with increasing O3concentration. Elevated O3concentration increased rate of yellow leaves, decreased chlorophyll content, increased membrane permeability, caused membrane lipid peroxidation, and leaf stomas were closed, photosynthesis was inhibited, and antioxidant capacity were weakened under the stress of the ozone, these eventually lead to lower biomass. Low concentrations of O3reduced leaf area, maked premature aging; Vegetables became dry, dehydration, and they appeared chlorosis, brown spots, new veins twist. These symptoms could not be restored when we stopped the fumigation under high concentrations of ozone.2, The impacts of ozone on the MDA content and soluble protein content of different vegetables and crops were not the same. The MDA content and soluble protein content of cabbage slightly gradually raised with increasing ozone concentration. The MDA contents of rape flowers in all of treatment were higher than the control, the highest increase compared with the control was144.5percent, while the soluble protein in ozone treatments were significantly (p<0.05) lower than the control. The change of Lettuce leaf MDA content were not obvious under ozone treatments, it was significantly (p<0.05) lower than blank at high concentrations (200ppb) ozone treatment, with a decline of128.5%, soluble protein contents were significantly (p<0.05) increased only at higher concentrations of ozone. Corn MDA content in the100ppb ozone treatment was significantly (p<0.05) lower than the control, with a decline of17.5%; In all ozone treatments, the soluble protein contents were respectively lower by36.5%,37.8%,44.8%compared with the blank.3、The SOD(Superoxide dismutase、POD(Peroxidase)、CAT(Catalase) contents of different vegetables and crops were changed disparately under the stress of ozone. The POD contents of cabbage leaves gradually increased with increasing ozone concentration, SOD contents of them did not change much, CAT content of them appeared a trend of increase firstly and they decreased secondly with increasing ozone concentration. No significant difference of SOD contents of rape leaf appeared between three ozone treatments, but all were significantly higher than the contrast (p<0.05), POD and CAT contents had a same change substantially, both were higher than the control treatment, while POD content of the200ppb treatment was higher than the contrast by334.6%, CAT content under200ppb was higher than the control by663.4%; SOD contents of Lettuce leaf were all lower than control, while100ppb and200ppb treatments reduced respectively by23.8%and26.5%compared to the blank, the POD contents increased with elevated ozone concentration, with the maximum increase of634.0%compared to the blank, CAT contents firstly increased and then decreased; SOD and CAT contents of crop leaf both were increased firstly and decreased secondly, but the POD contents in three ozone treatments were significantly higher, with the highest increase by142.9%compared to the blank.4、Ozone had a influence on the abundances of microorganism in nitrogen cycle of the different cabbage soil. The impact of ozone on AOA genes copies in cabbage soil was not obvious, only150ppb treatment was significantly (p<0.05) different with the rest. AOB gene copies were significantly (p<0.05) lower than contrast, three treatments were lower respectively by33.5%,58.5%,57.6%compared with the control, nosZ gene copies in150ppb and200ppb treatments were lower than that in control group, while that in100ppb treatment (p<0.05) was higher than others; AOA gene copies in rape soil in three ozone treatments were respectively lower than the control by13.6%,24.9%,51.2%, AOB gene copies had not been changed much under ozone stress, only150ppb treatment was significantly (p<0.05) different with other treatments, nosZ gene copies in ozone treatments were significantly lower than the control, with the highest decrease by142.9%compared to the blank; AOA gene copies in lettuce soil were gradually reduced with the ozone treatments, AOB gene copies in150ppb and200ppb treatments were significantly lower than those in the control and100ppb treatments, respectively reduced by34.4%,72.0%compared with control, nosZ gene copies in ozone treatments were respectively higher than those of contrast by364.9%and256.3%,47.7%.5、The abundances of microorganism in nitrogen cycle of the different grain crops soil also were changed under the stress of ozone. The impact of ozone on AOA genes copies in crop soil was not obvious, but AOB gene copies were decreased significantly (p<0.05), with the decrease of30.2%,38.9%,56.7%compared with the control, nosZ gene copies in ozone treatments were all higher than that of the control, with a increase of566.0%,55.2%,117.9%respectively compared with blank, AOB and AOA gene copies in rice soil were changed much with ozone, those in40ppb,80ppb,120ppb treatments were lower than that of CK by15.2%,68.1%,69.1%respectively, and AOA gene copies were with a decrease of38.4%,64.9%,43.2%respectively compared with blank treatment, nosZ gene copies in ozone treatments were slightly higher than the control; The AOA、AOB、NOB、nosZ and nifH gene copies in the winter wheat soil were changed disparately under the stress of ozone, with the numbers differing among the different stages of the wheat and the different soil layers. In jointing stage, nifH gene copies in each ozone treatments were reduced respectively by32.0%,76.3%,74.2%compared with a blank in0-10cm soil layer. From the analysis results of the composition of five functional bacteria in the soil, we concluded that the law of quantities was NOB>AOA>nosZ>AOB>nifH, with the addition of the results of two principal component analysis, we could get that the tolerance capacity to environmental factors of AOA gene was the best, followed by NOB gene, and then were the nifH gene and nosZ gene, the patience of AOB gene to environmental factors was the weakest in the wheat soil. |
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