Abstract: Stipagrostis pennata, a typical psammophyte, can resist drought due to the formation of a special rhizosheath. Plant, soil and microbe work together to contribute to the formation of the rhizosheath. Sand sterilization experiments were carried out in the laboratory to investigate the function of soil microbes on seed germination, seedling growth and rhizosheath formation of Stipagrostis pennata. The results showed that: (1) On sterilized sand, seed germination rate was lower when compared to seeds planted on non-sterilized sand (control treatment). With the help of soil microbes, seed germination rate stablized around 25% after 19 d-planting on the non-sterilized sand. (2) Sand sterilization also dramatically reduced the seedling survival rate to near 5%, however, the rate was as high as 36.54% on non-sterilized sand. (3) After 40 d-planting, the seedling plant height on non-sterilized sand was 1.72 times greater when compared to sterilized sand plots. Fresh, light green seedlings were observed on non-sterilized sand while wilting seedlings were found in sterilized plots. (4) Sand sterilization was suggested to impede the formation of rhizosheaths. Sand sterilization visibly weakened the sand adhesion ability of the root. The root hair wilted due to the loss of protection from root and microbe exudate. In conclusion, soil microbes play an important role in seed germination, seedling survival and rhizosheaths formation of Stipagrostis pennata.

Key words: Stipagrostis pennata, rhizosphere, seeds germination, microorganism