EFFECTS OF GLUTATHIONE ON PHOTOSYNTHETIC CHARACTERISTICS OF PEPPER LEAVES UNDER AUTOTOXICITY

Effects of Glutathione(GSH) with different concentrations on chlorophyll content(Chl),photosynthetic parameters and chlorophyll fluorescence parameters in leaves of pepper were investigated,using pepper varieties of 'Longjiao No.5' and 'Qicunhong' under autotoxicity.Results showed that Chl,net photosynthetic rate(Pn),stomatal conductance(Gs) and transpiration rate(Tr) declined sharply,but intercellular CO2 concentration(Ci) increased significantly after treated with leaf aqueous extracts of 50g·L-1.The contents of Chl,Pn,Gs and Tr increased,while Ci increased at first then decreased rapidly after treated with exogenous GSH,which suggested that Pn reduction was mainly due to non-stomatal factors.Maximum photochemical efficiency of PSII(Fv/Fm),maximal efficiency at open centers in the presence of NPQ(Fv′/Fm′) and actual quantum yield of PSⅡelectron transport(ФPSII) declined,but origin fluorescence(Fo) increased under autotoxicity.The peppers treated with GSH had higher Fv/Fm,Fv′/Fm′ and ФPSII,while Fo decreased significantly under different concentrations of GSH compared with those treated by water or leach liquor only.It was illustrated that exogenous GSH regulated the changes of leaf gas exchange and chlorophyll fluorescence parameters,especially,by preventing the accumulation of CO2 in the leaves which was associated with an improvement in the non-stomatal factors,then alleviated the barrier of continuous pepper cropping caused by autotoxicity.There were certain alleviate effects of exogenous GSH on the two varieties of peppers under autotoxicity,among the glutathione concentrations used,50 and 30 mg·L-1 were the optimum concentrations for 'Longjiao No.5' and 'Qicunhong',respectively.