Effects of saline-waterlogging and dryness/moist alternations on seed germination of halophyte and xerophyte

In arid zones, precipitation distribution is extremely uneven, with saline-waterlogging and dry-moist cycles appearing frequently, which negatively impact on seed germination and seedling establishment. The responses of two halophytes, Suaeda physophora and Haloxylon ammodendron, and a xerophyte, Haloxylon persicum, to saline-waterlogging and dry-moist cycles were studied. The results showed that aeration increased seed germination for all species when seeds were submerged in NaCl, especially for xerophyte. Compared with S.physophora and H.ammodendron, seed germination, recovery germination, and total germination of H.persicum were much lower when seeds were submerged in 700mm NaCl, especially for the recovery germination and total germination of nongerminated seeds when the seeds were desiccated and then transferred to distilled water. However, when the seeds were submerged in 700mm NaCl with aeration, the seed germination, recovery germination, and total germination of nongerminated seeds transferred to distilled water increased dramatically for H.persicum. No adverse effect of desiccation was found on those values of nongerminated seeds pretreated in NaCl with or without aeration for the two halophytes. In conclusion, seeds of the two halophytes were more tolerant to waterlogging and dry-moist cycles than seeds of the xerophyte during emergence under saline conditions; these traits may be important for halophytes to survive extreme saline environments during the seed germination stage.