Effects On The Physiological Characteristics Of Three Poa Prartensis Accessions From Shanxi Province Under NaCl Stress

Kentucky bluegrass as one kind of cool season turfgrasses is cultivated widely.Salinization of soil as a global problem,is aggravating with increasing population and deteriorative ecological environment.It has been proved important theoretical and realistic value for us to research on salt tolerance of Kentucky bluegrass.Three accessions(HY,YX,and QS)of Kentucky bluegrass from Shanxi Province were compared under different NaCl concentrations(0,50 mmol/L,100 mmol/L,150 mmol/L,200 mmol/L,250 mmol/L,and 300mmol/L).Physiological parameters such as relative water content(RWC),the contents of proline,soluble sugar,soluble protein,and photosynthesis characteristics including net photosynthesis rate(Pn),transpiration rate(Tr),stomatal conductivity(Gs)and intercellular CO2 concentration(Ci)were measured and analyzed.The results showed that leaves relative water contents(RWC)and soluble protein(SP)decreased as the increasing concentration of NaCl in three accessions.The declining trends of RWC in three Poa pratensis accessions are different.Among them the RWC of QS accession was higher than HY accession.The superoxide dismutase(SOD)activities and soluble sugar(SS)contents increased firstly and then decreased in YX and QS accessions,while HY accession showed an continual increasing trend.The proline contents rose as the increasing of NaCl concentration in the three Poa pratensis accesions.Meanwhile,the photosynthetic characteristic values including Pn,Tr and GS decreased as the increasing of NaCl concentration,the fall range of HY accession was lower than YX and QS accession,and the difference of QS accession compared with control was least.The intercellular CO2 concentration decreased when stressed by lower NaCl concentration(50 mmol/L,100 mmol/L,150mmol/L),and increased in higher NaCl concentration(200 mmol/L,250 mmol/L,300 mmol/L).A comprehensive analysis of salt tolerance indicated that the salt threshold of QS accession was 200 mmol/L,YX accession was 250 mmol/L.HY accession had not appeared salt threshold until NaCl concentration reached 300 mmol/L.In summary,the salt tolerance ranked as HY>YX>QS.The aboveground parts of Kentucky bluegrass were more sensitive to salt stress than underground parts.