不同外源硒对砷胁迫萝卜的光合特性影响

Effects of different exogenous selenium sources on photosynthetic characteristics of arsenic-stressed radish

砷对人类健康存在潜在威胁,蔬菜是人体砷摄入的主要来源之一。硒是对砷毒性有拮抗作用的微量元素。目前关于硒对砷胁迫萝卜光合特性的影响鲜见报道。本文采用盆栽试验,研究施加不同浓度亚硒酸钠(Se(IV))、硒酸钠(Se(VI))、酵母硒(Se-Y)和麦芽硒(Se-M)对砷胁迫萝卜的净光合速率(P_(n))、气孔导度(G_(s))、胞间CO_(2)浓度(C_(i))和蒸腾速率(T_(r))光合特性的影响。结果表明;低浓度硒(≤6 mg·L^(-1))可增强砷胁迫下萝卜的抗逆性,提高P_(n)和T_(r),降低C_(i),从而增强萝卜的光合作用;高浓度硒(≥24 mg·L^(-1))会对萝卜产生毒害作用,减弱萝卜的光合作用;有机硒(Se-Y、Se-M)比无机硒(Se(IV)、Se(VI))更能减轻砷对萝卜的毒理学效应;Se-M对萝卜P_(n)、G_(s)、C_(i)和T_(r)光合特性的影响均最大。

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 exogenous selenium sources on the photosynthetic properties of radish under arsenic stress in terms of the net photosynthesis rate(P_(n)),stomatal conductance(G_(s)),inter-cellular CO_(2)concentration(C_(i)),and transpiration rate(T_(r)),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(P_(n)),stomatal conductance(G_(s))and transpiration rate(T_(r)),and decrease the inter-cellular CO_(2)concentration(C_(i)),thus enhancing the photosynthesis of radish.However,over concentration of selenium(≥24 mg·L^(-1))can be toxic to radish and reduce radish photosynthesis.The treatment groups applying organic selenium(Se-Y,Se-M)and low concentrations of Se(IV)more significantly alleviated the damage of arsenic to radish and enhanced radish photosynthesis.The treatment groups with high concentrations 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 significantly increased by 30.49%,Gs significantly increased by 136.19%,Gi significantly decreased by 8.60%,and Tr significantly 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.