Influence Of Simulated Acid Rain On Photosynthetic And Physiological Characteristics And Yield Of Wheat

China is a large agricultural country,the acid rain against more and more attention on crops,acid rain leads to crop dysphasia and the decline in yield and quality.The field trial and pot cultivation and study of acid rain on the physiological indexes of wheat using the winter wheat(number 68 of wheat in Anhui)as the research object.Rain is divided into three different concentrations including p H5.6(CK),p H4.0(T1)and p H2.5(T2).The research sprayed the simulated acid rain on wheat after emergence and before the jointing stage began,and measures physiological indexes of the wheat leaf from jointing stage,studies the growth situation of wheat in different growth stages under the influence of the simulated acid rain and yield stress effect.Specific test results are as follows:(1)The different acid rains have different influence,the leaves of wheat under T2 treatment were severe visible damage,appearing rusts from heading stage,and the leaves of wheat under T1 treatment have no obvious damage;the height of wheat under T1 and T2 treatment were decreased than CK,the decline was 2.97% and 15.17%,the height of wheat under T2 fells significantly;the ear length of T1 and T2 were decreased by 0.71%and 2.12% than CK.The effect of acid rain on the ear length of wheat was very weak.(2)With the decrease of simulated acid rain's p H,the net photosynthetic rate of wheat was enhancing inhibited,in the whole growth period of wheat,the net photosynthetic rate of T2 was significantly lower than that of CK,the decline of the flowering period reached a very significant,at a decline of 51.88%,the net photosynthetic rate of T1 was lower than that of CK,but it was not significant.During the growth period of wheat,there was a midday depression phenomenon,it will effectively inhibit the net photosynthetic rate of wheat.(3)The transpiration rate decreased as the simulated acid rain's pH showed a decreasing trend,but in the whole growth period the decline of the transpiration rate of T1 than CK is not significant,the transpiration rate of T2 at jointing stage,heading stage,and filling stage was not significant than that of CK,Only at the flowering stage,the transpiration rate of T2 decreased significantly,at a decline of 39.31%.(4)With the decrease of pH value of simulated acid rain,the utilization rate of lightenergy of wheat at different growth stages showed a trend of decrease.T1 compared with CK only in grain filling stage,the utilization rate of light energy decreased significantly,while T2 decreased significantly at heading stage compared with CK,which showed a significant decrease in the other three growth stages.(5)The water use efficiency of wheat's leaves decreased as the simulated acid rain's pH decreased,in the whole process of growth and development,the water use efficiency of T1 and T2 was not significantly lower than that of CK.Although at the jointing stage the water use efficiency of T2 fell as high as 65.12% than that of CK,due to the different moments of individual water use efficiency values are very larger than the average value,it did not pass the significant test.(6)With the decreasing pH value of simulated acid rain,wheat stomatal conductance also decreased,but in wheat jointing stage and heading stage between the different treatment differences is not obvious,the wheat flowering stage T2 compared with CK stomatal guide is reduced significantly,arriving at the grain filling stage reached extremely significant difference level.The stomatal conductance of CK was decreased,but it was not significant in the whole growth period of T1.(7)With the decrease of the pH value,in each growth stage of wheat chlorophyll content showed CK>T1>T2,which the content of chlorophyll a in the filling stage T1 and T2 than CK significantly decreased,and this difference showed extremely significant.(8)The simulated acid rain has a great influence on the yield of wheat,the 1000 grain weight of wheat of T1 and T2 decreased by 7.52% and 16.89% respectively than that of CK,the decrease was very obvious,and the difference was very significant.There was no big difference in the number of grains per spike between the three groups;the influence by acid rain is very weak.There was No inhibitory effect of simulated acid rain on wheat grain production,but a great influence on the growth of wheat grain.The pot yield of wheat of T1 and T2 decreased by 5.94% and 18.32% respectively than that of CK,The difference of T1 was not significant.But the decrease of T2 was very obvious.The results showed that when the simulated acid rain treatment under p H4.0,the net photosynthetic rate,transpiration rate,light use efficiency,water use efficiency,stomatal conductance and chlorophyll content of leaves of wheat had no significant change,it showed that wheat had certain resistance to acid rain,but when the simulated acid rain's pH decreased to 2.5,the indexes of wheat decreased significantly.In addition,the simulated acid rain of T1 and T2 showed very significant inhibitory effect on wheat yield,it showed that the effect of acid rain on crops should not be ignored.