Stress Effects of Simulated Acid Rain on Photosynthetic Characteristics of Field-grown Spring Wheat at the Jointing Stage

In order to investigate the effect of acid rain on photosynthetic characteristics of spring wheat,spring wheat at the jointing stage was sprayed with simulated acid rain at different pH levels of 1.5,2.5,3.5,4.5 and 5.6,and then,the yield and the photosynthetic parameters of spring wheat leaves were monitored.The results indicated the pH value of simulated acid rain was significantly positively correlated with net photosynthetic rate,stomatal conductance,transpiration rate,water use efficiency and the relative chlorophyll content,whereas was significantly negatively correlated with intercellular CO2 concentration.The net photosynthetic rate reduced in the range of 4.08% to 67.04%,stomatal conductance reduced in the range of 17.44% to 58.44%,transpiration rate reduced in the range of 12.08% to 48.08%,intercellular CO2 concentration increases in the range of 9.01% to 14.29%,the chlorophyll relative content reduced in the range of 12.16% to 37.23%.After simulated acid rain treatments the net photosynthetic rate was significantly positively correlated with stomatal conductance,transpiration rate,water use efficiency,and the relative chlorophyll content,and the net photosynthetic rate was negatively correlated with intercellular CO2 concentration.The transpiration rate was significantly positively correlated with stomatal conductance,water use efficiency,and the relative chlorophyll content,and the transpiration rate negatively correlated with intercellular CO2 concentration.In short,effect of simulated acid rain on photosynthetic characteristics of spring wheat leaves increases with the increase of hydrogen ion concentration more and more remarkable.