Effects of different exogenous selenium sources on photosynthetic characteristics of arsenic-stressed radish
In this paper,the effects of different concentrations of sodium selenite(Se(Ⅳ)),sodium selenate(Se(Ⅵ)),yeast selenium(Se-Y),and malt selenium(Se-M)were investigated in a pot experiment to study the effects of different exog-enous selenium sources on the photosynthetic properties of radish under arsenic stress in terms of the net photosynthesis rate(Pn),stomatal conductance(Gs),inter-cellular CO2 concentration(Ci),and transpiration rate(Tr),respectively.The results show that with the increase of different exogenous selenium concentrations,the moderate low concentration of selenium(≤6 mg·L-1)could enhance the resistance of radish to arsenic stress,increase the net photosynthetic rate(Pn),stomatal con-ductance(Gs)and transpiration rate(Tr),and decrease the inter-cellular CO2 concentration(Ci),thus enhancing the photo-synthesis of radish.However,over concentration of selenium(≥24 mg·L-1)can be toxic to radish and reduce radish pho-tosynthesis.The treatment groups applying organic selenium(Se-Y,Se-M)and low concentrations of Se(IV)more significant-ly alleviated the damage of arsenic to radish and enhanced radish photosynthesis.The treatment groups with high concentra-tions of Se(Ⅳ)and Se(Ⅵ),on the other hand,were toxic to radish and inhibited its photosynthesis.Se-M has the greatest impact on the photosynthetic characteristics of radish,including Pn,Gs and Tr.Compared with the control group,Pn signifi-cantly increased by 30.49％,Gs significantly increased by 136.19％,Gi significantly decreased by 8.60％,and Tr signifi-cantly increased by 21.42％.This study provides a reference for the safe and rational application of selenium to alleviate the effect of arsenic on agricultural products and to maximize the benefits of selenium in agricultural production.
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