Effects of salt stress on seed germination of Apocynum venetum and Poacynum hendersonii

In this study, Apocynum venetum and Poacynum hendersonii were used to study the effects of salt stress on seed germination and seedling growth at different concentrations (0, 0.3%, 0.6%, 0.9%, 1.2%, 1.5%, 1.8% and 2.1%) of NaCl. The results showed that with increasing NaCl concentration, germination rate (GR), germination potential (GP), and germination index (GI) of A. venetum and P. hendersonii seeds showed a remarkably decreasing trend, with delayed mean germination time, and inhibited length of germ and radicle. The degree of inhibition on each index was more obvious at higher concentrations (1.5%～2.1%). From the two species, there was no significant difference in germination rate and germination potential at low concentration (P > 0.05), and the effect of high concentration on A. venetum was significantly higher than that of P. hendersonii (P < 0.05). When NaCl concentration was 0.9%, the length of germ P. hendersonii was significantly longer than that of A. venetum, and the other differences were not significant (P > 0.05). At 0.3%, 0.6%, 0.9% and 2.1% the length of radicle P. hendersonii was significantly longer than that of A. venetum, and there was no significant difference in other concentrations (P < 0.05). The relative salt injury rate was higher in A. venetum seed than P. hendersonii, but the difference was not significant (P > 0.05). Thus, the salt tolerance was higher in P. hendersonii than A. venetum. The optimum salt concentration range of A. venetum was 0～1.5%, while the optimum salt concentration range of P. hendersonii was 0～1.8%.