Abstract: By the method of polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), this paper studied the genetic polymorphism of exon 1 and intron 1 in the aquaporin gene of seven species of Stipa in the meadow steppe (forest steppe), typical steppe, and desert steppe of Inner Mongolia. The results showed that exon 1 had the genotypes of AA, BB and CC, while intron 1 had the genotypes of DD, EE, FF and GG. There existed gene polymorphism in inter-species but not in intra-species. All the test species displayed genetic monomorphism and 100% of purity. From the viewpoint of genotype′s geographical distribution, AA existed in the Stipa species on meadow steppe (forest steppe), typical steppe and desert steppe, BB and CC only existed in the species on desert steppe, DD was found in the species on meadow steppe (forest steppe) and typical steppe, and genotypes EE, FF and GG were detected in the species on desert steppe. The plants on desert steppe exhibited the strongest xeromorphic characteristics, and 3 species of Stipa on the desert steppe had abundant genetic polymorphism.

Key words: 23 years-located experiment, Calcareous soil, Organic matter, Total phosphorus, Available phosphorus