Effects of salinity and scarifying seed coat on ion content of embryos and seed germination for Suaeda physophora and Haloxylon ammodendron

Suaeda physophora and Haloxylon ammodendron are two common halophytes in the Zhunger Basin, an and region which is located in Xinjiang, the northwest province of China. Seed coats were scarified to investigate the effects of salinity and scarifying seed coat on ion content of embryos and seed germination for the present species. The Na+ concentration in embryos of scarified seeds in NaCl was higher than that of intact seeds in NaCl and of scarified or intact seeds in distilled water for both species. The K+ concentration in embryos of scarified seeds was lower than that for intact seeds in distilled water or in NaCl for both species. Scarifying the seed coat had no effect on seed water uptake and final seed germination for both species. NaCl markedly decreased the percentage of normal seedlings for both species, especially for that of scarified seeds. Seeds germinated rapidly for both species, especially for S. physophora in distilled water. In conclusion, the seed coat does not impair water uptake, but plays an important role in inhibiting Na+ influx into and K+ efflux from the embryo to protect the seed from ion toxicity to ensure seedling establishment in the present two species. These traits may be adaptations to salinity for the two halophytes in an and region.