Responses of Germination and seedling growth in Leymus chinensis to Sodic-saline Soils and their adaptive mechanisms

摘要

We investigated the effect of soils with different pH on the germination, seedling growth and ion distribution of Leymus chinensis. Soils with different pH values were obtained by mixing the nonsodic-saline soil and sodic-saline soil at different ratios. Results showed that seed germination percentages in soils with pH 7.49-9.14 were all higher than 50%. and the seedlings could grow normally. When the pH was higher than 9.53, the germination percentage was lower than 50% and only some of the seedlings could grow normally but when the pH was higher than 9.86. germination was lower than 3.3% and most of the seedlings died within 50 days after their germination. Faster seedling growth rate in the early stage and more tillers during the whole growth stage were obtained in mild sodic-saline stresses. With the increase of sodic-saline stress. Na+content in shoots and roots were increased. while the content of K+, Ca2+and the ratio of K+/Na+and Ca2+/Na+were all decreased. However, the shoots of L. chinensis showed higher K+/Na+ratio while lower Ca2+/Na+ratio compared with that of the roots. The ratios of K+/Na+were higher than 1 when the pH was no more than 9.14 and this showed that maintaining high content of K+made the L. chinensis more adaptive to the sodic saline soil. Selective uptake of K+and Na+, maintaining higher level of K+/Na+and Ca2+/Na+ratios, strong K+, Ca2+transport activity from roots to shoots were the main mechanisms for L. chinensis adapting the sodic saline stress.