Effect of exogenous Ca on the physiology and growth indicators of pakchoi under foliar and root fluorine stress

摘要

Fluorine(F)is not an essential element for vegetation and excessive F can be phytotoxic to plant growth,which can cause fluorosis to human beings by ingesting F-contaminated plant.Although there have been some studies focusing on the tox-icity of F to plants and the retarding effect of Ca to F-stress plant,atmospheric F contamination to veg-etation and the role of the application of foliar Ca are scantly reported.This study investigated several biochemical parameters to evaluate F toxicity under both F-exposure(root and leaf F-exposure)and the remedial effects of foliar Ca.The results showed that F concentration of pakchoi leaves was corre-lated with exogenous F level positively in both foliar and root F-exposure series,and F concentration of pakchoi roots was only changed under root F-expo-sure treatments.Ca supplement(0.5 g/L and 1 g/L)significantly decreased plant F concentration.Both F-exposure treatments caused lipid peroxidation in plants and exogenous Ca alleviated the toxicity of F to pakchoi.Meanwhile,chlorophyll-a concentration was decreased by foliar and root F,whereas chloro-phyll-b concentration was only affected by foliar F,and chlorophyll-a concentration could be elevated by exogenous Ca but chlorophyll-b could not.It was con-cluded that both atmospheric and root F can impair pakchoi growth and disturb photosynthesis,and foliar Ca showed an ameliorative effect to F toxicity of pakchoi through alleviating chlorophyll decomposi-tion,increasing protein content and alleviating oxida-tive damage.