Salt tolerance comparison among four Populus tree seedlings in shelter belt of Yuli County,Xinjiang

Four populars are the main trees in the shelter belt of Yuli County,Xinjiang Uygur Autonomous Region,including Populus × xiaozhuanica "Zhongtian",Populus alba var.pyramidalis,Populus alba × Populus alba var.pyramidalis and Populus euphratica.Six ecophysiological indexes of which is leaf proline content,K+/Na+,Cl-content,SOD activity,MDA content and δ13C value were chosen to evaluate salt tolerance of four Populus tree seedlings.The purpose of this study was to choose suitable trees for salt tolerant shelter belt for Yuli County.The results showed that the salt tolerance of P.× xiaozhuanica "Zhongtian" and P.euphratica were higher in four Populus trees,because they suffered slightly from soil salt stress,reflecting in lower leaf MDA content and higher δ13C value.However,their salt tolerance mechanism were different: P.× xiaozhuanica "Zhongtian" tolerated salt by improving leaf Cl-content and SOD activity whereas P.euphratica resisted salt by increasing leaf proline content and K+/Na+.