2.1 Experimental materials
Stipa krylovii Roshev. is a Gramineae C3bunchgrass, widely distributed in the Inner Mongolia Steppe, including the meadow grasslands – typical grasslands transition in the east, most areas of typical grasslands in the center and some areas of desert grasslands in the west (Liu, 2004). Significant genetic differentiation of S. krylovii is found among regions or habitats by DNA-based markers (Wang et al., 2006b), and both local adaptation and phenotypic plasticity (environmental modification) play important roles in affecting individual responses to environmental changes (Liu et al., 2023).
In S. krylovii main distribution areas, seeds of S. krylovii were collected within 9 populations from three regions (the eastern, middle and western regions), and the climatic characteristics of collection sites are shown in Table 1. Among them, the aridity index was calculated by the ratio of regional precipitation to potential evapotranspiration. The collected seeds were dried in the laboratory and stored in envelope bags at -4 ℃. In the spring of 2022, seeds were germinated and six-month seedlings were used for the following experiment.