中文摘要：

研究了不同浓度（0、10、20、50、801、00 mmol.L-1）复合钠盐（NaCl、Na2CO3和Na2SO4）胁迫对白桦和红桦种子萌发的影响。结果表明：盐胁迫对两种桦树种子的萌发均具有明显抑制作用,随着盐胁迫浓度的增大,10、20、50和80 mmol.L-1的盐胁迫下的白桦和红桦种子的萌发率从对照（0 mmol.L-1）的100%和94.44%分别减小到80.00%、48.89%、11.11%、0%和77.78%、52.22%、18.89%、3.33%,不同浓度盐处理与对照间及各浓度间均差异显著。未经盐胁迫处理种子的萌发指数和幼苗活力指数最大（白桦种子分别为2.00和268.94;红桦种子分别为2.24和262.39）,二者均随盐胁迫浓度的提高而减小。从萌发进程和种子全部致死时的盐胁迫浓度看,红桦种子萌发比白桦种子对盐胁迫具有更强的耐受性,但其对盐胁迫的耐受性非常有限,二者均应属盐胁迫敏感性的种子。

英文摘要：

The stress effects of different concentrations（0、10、20、50、80、100 mmol·L-1 respectively） of mixed sodium salt（NaCl,Na2CO3 and Na2SO4） on the seed germination of two betula spp.were examined.The results demonstrated that the seed germination of these two species was significantly inhibited by salt stress.Stressing the seeds of Betula platyphylla and B.albo-sinensis under 10,20,50 and 80 mmol·L-1 resulted in a decrease of germination percentage from 100% and 94.44%（concentration of 0 mmol·L-1,control） to 80.00%,48.89%,11.11%,0% and 77.78%,52.22%,18.89%,3.33% respectively.Significantly differences were observed both between all concentrations of stressing salt and control and between different treatments of salt concentrations.Both germination index and vigor index of non-stressed seeds of tow species were maximized and the maximums of them were 2.00 and 268.94 for B.platyphylla,and 2.24 and 262.39 for B.albo-sinensis respectively.With the increase of salt concentration,the decline of germination index and vigor index of two species was observed.According to germination course and salt concentration which caused death of all treated seeds,it seems that a higer tolerance of B.albo-sinensis seeds to complex salt stress than that of B.platyphylla seeds was observed,but both seeds of tree species belong to salt-sensitive species due to their very limited tolerance to salt stress.