Effects Of Straw Returning On The Ecological Stoichiometry Of Soybean Under Elevated Ozone Concentration

The ozone stress indirectly affects the absorption and distribution of nutrients by affecting the growth and development of plants.The straw returning releases various nutrients and affects the growth of plants.In this study,the open-top gas chamber method(OTCs)was used to investigate the effects of ozone stress(CK: environmental concentration,T1: 80±10 nmol·mol-1,T2: 110±10 nmol·mol-1)on the stoichiometry of C,N,P and K in soybean organs and root soils,and to reveal the obvious changes of soybean ecological stoichiometry and the nutrient limitation of soybean growth under under straw returning(S1)and not straw returning(S0)treatment.The results showed:(1)Under conditions of elevated ozone concentration,the straw returning to the soil caused the organic C content in the roots to decrease significantly in podding,the N content decreased during the whole growth stage,while the P and K of contents in T2 treatment in the roots increased significantly in branching;The C:N,C:P and C:K of roots were decreased significantly in T1 treatment in the flowering stage,and N:P decreased significantly and was lower than 14 during the whole growth stage;(2)Under conditions of elevated ozone concentration,the straw returning had no significant effect on the organic C content of the stems,the N content decreased significantly,the P content first decreased and then increased significantly under T2 treatment,and K content decreased significantly in branching;C:N increased,C:K increased significantly in branching stage,C:P increased significantly under T2 treatment in branching and flowering stages,and N:P decrease significantly under T2 treatment and is less than 14;(3)Compared with not straw returning,the straw returning caused the organic C and K content of leaves increase under T2 treatment significantly during the whole growth period,while the N content decreased significantly,The P content increased significantly in branching;C:N increased significantly under T2 treatment during the whole growth period,while the C:P increase significantly in the podding stage,and the N:P was lower than 14 in the whole growth period,and the branching stage and the flowering period were significantly reduced;(4)Compared with not straw returning,the straw returning increased significantly the soil organic C content and N content in CK and T1 treatment in the early growth stage,The P content increased in the all ozone treatments;N:P decreased significantly under the T1 treatment in the podding stage.Straw returning can reduce the utilization rate of N,P and K in soybean roots and stems under ozone stress,increase the utilization rate of N and organic C and K content of leaves,and increase the soil organic C content and the N content in the early growth stage,and increase soil phosphorus activity in the late growth stage.The growth of soybean is limited by N between the elevated ozone concentration and straw returning under the whole growth stage.