Screening and identification of drought tolerance varieties of wild Elymus sibiricus at seedling stage

Elymus sibiricus selections suitable for growing in semi-arid areas were screened out according to their response to drought stress at the seedling stage; this provides the basis for artificial grassland construction, grassland replanting improvement and grassland ecological restoration in semi-arid areas of Qinghai Tibet Plateau. This study selected material from 19 wild Elymus sibiricus provenances from different habitats in Huzhu County, Menyuan County, Datong County, and Gangcha County of Qinghai Province. Taking Elymus sibiricus ‘Qingmu No.1’ and E. sibiricus ‘Chuancao No. 2’ as reference materials, the selections were cultivated in pots in a simulated typical drought stress environment (soil relative water content 45%～50% of field water capacity). Phenotypic and physiological indexes of Elymus sibiricus were determined in fixed plants. The drought tolerance of the wild and cultivated Elymus sibiricus selections at the seedling stage were comprehensively evaluated by the subordinate function method. The results were as follows: With increased numbers of drought stress days, the plant height, leaf area, dry matter accumulation percentage and chlorophyll content in the control group showed an increasing trend, while the percentage root dry matter accumulation and relative electrical conductivity showed a decreasing trend. Compared with the control group, the plant height, relative growth rate, relative survival percentage and chlorophyll content of Elymus sibiricus selections in the treatment group decreased continuously with increased numbers of drought stress days, while the relative conductivity value increased continuously. The morphological plasticity of plant height, leaf area and root system dry matter accumulation is an important way for Elymus sibiricust to adapt to drought environments at the seedling stage. Among the 21 Elymus sibiricus materials tested, the 15-195 Elymus sibiricus selection from Datong County had the strongest drought resistance and was notably better than the other materials.