[Effects of salinity stress on poplars seedling growth and soil enzyme activity]

A pot culture experiment with two clones of poplars (P1 and P2) showed that soil salinity had a definite inhibitory effect on the establishment and growth of seedlings. The survival rate, seedling height and weight, and root weight were all declined with increasing soil salinity. When the salinity was 0.2%, 0.4%, 0.6% and 0.8%, the shoot growth of P1 and P2 decreased by 23.24%, 48.56%, 70.76% and 83.33%, and 71.77%, 83.25%, 86.28% and 91.39%, respectively, in comparing with the control. Regressive analyses showed that soil salinity had a linear relationship with chlorophyll content, and a binomial relationship with leaf proline content. The activities of soil beta-glucosidase and L-asparaginase were decreased with increasing soil salinity. When the salinity was 0.2%, 0.4%, 0.6% and 0.8%, the beta-glucosidase activity in P1 and P2 soils decreased by 10.96%, 20.07%, 30.96% and 37.44%, and 11.21%, 18.94%, 34.89% and 41.31%, respectively. The salinity tolerance of P1 was better than that of P2.