Nacl Stress Inhibited The Study Of The Mechanism Of Photosynthesis Of Wheat, Corn Seedlings

Wheat seedling and maize seedling were treated with NaCl in differenconcelltration, Photosynthtis characters were measured after 10 days. It was fOund thatthe potosynthesic rate was stiInulated by 50nunoMi NaC1, dribited by 100rnmoimNaCl and the higher the salt degree the more it was dribited; stomatal conductancereduced under NaC1 stress; substomata1 CO2 concentration reduced at first then risen. Itwas suggested that the stomatal ltritation factr is domjnating When NaClconcndion is 1oW with the increase of the NaC1 concendation then non-stomatalfacor become the dominating factor gradua1lYMaize seed1ing was treated with 100mxnormaC1, PhotOsrothesis ratC andother parameters were measures after 4h,2d,3d,5d,7d and 9d respectively 'fhe resultsshow that the photosynthesis rate decreased wtth time, While stomatal conductricereduced, haher substomata CO2 cotheni reduced at first then increased gradua1lyMDA, Cl-,Pi and soluble carbohydrate content increased, Whi1e Chia/Chalb and FvN.decreased, and the acivity of MDH and PEPCase reduced. It is suggested tha thereasons for photosynthesis chbition by NaCl stress are the interaction of multi-factors.The stomatal lndon factors caused by osmotic stress is dothenating When the stressperiod is Short, wtth the prolonging of stress period then non-stomatal factrs becomethe domjnating faCtor gfadually The increase of actve oxygen is the basicnon-stOmatal liAnting factor.wheat seedling were treated wt 100mmown NaCl, photosynthesis rate and otherparameters were measured after 15d. The result show that when wheat seed1ing underNaCl stress, photosguthesis rate decreased, stomatal conductallce reduced, substomata1COz concentration reduced, Na+. Cl-. Pi and solub1e carbohydrate cond of leofincreased, while K+ content decreased, content of free Ca2+. Mgz+. Fe"(includingFe'b does not change obviously Na+. Pi and soluble carbohydrate of chorop1astincreased, while K+. Ca2+. Mgz+. Fe"(including Fe'b decreased marked1y. All kind ofions and soluble carbohydrate of aPoplasndc fluld are decreased, pH enhanced, Whileosmotic PotCntial decreased, The differences of soluble carbohydIate conieni, pH andosmotic potenhal between aPOPlasmic fiuld and cel1 juice are smaller 1t is suggestedthat the reasons for Photosynthesis inhibition by NaCl stress are the interaction ofmulti-factrs, Which incude stOthatal ldriation factOrs caused by osmOtc Stress, ioinctoxicfy of Na+ and CY,and ionic deficiency of K+ \ Ca2+. Mgz+. Fe"(including Fe'+),feedback inhibition of soluble carbohydrate, and Chls' reduce.