Growth and photosynthesis characteristics of wheat (Triticum aestivum L.) under arsenic stress condition

A hydroponic experiment was employed to study the effects of arsenic addition on the growth of wheat(Triticum aestivum L.)and its photosynthesis characteristics,such as net photosynthesis rate(Pn),stomatic conductance(Gs),intercellular CO2 concentration(Ci),and transpiration rate(Tr).The results showed that addition of As in the hydroponic solution decreased the growth of root and shoots and the fresh biomass of roots and shoot was negatively related to the As concentration added,with the correlation coefficient(R2)being 0.927 and 0.9086,respectively.With increasing of As concentrations from 0 to 90 mg/L,Pn,Gs and Tr decreased significantly.When As was less than 30 mg/L,the Ci decreased gradually,which resulted in the increase of stomatal limitation values(Ls)and thus the decrease of Pn to form the limitation of stomat.However,when As was greater than 30 mg/L,the increasing of Ci induced the decease of Ls and Pn,and thus the limitation of non-stomat.The water unitilization efficiency(WUE)and Ls of wheat leaves increased at As 30 mg/L,but the WUE deceased at As60 mg/L due to the arsenic toxicity in wheat.The content of chlorophyll had no changes at As of 0-10 mg/L,but decreased significantly at As of 30 mg/L.The results suggested that arsenic mainly inhibited the growth of roots and induced the limitation of both stomat and non-stomat to finally influence growth and development of wheat.