Phenotypic and Biochemical Responses and Drought Resistance of Allium polyrhizum to Drought Stress.

Allium polyrhizum is an important native species in arid and semi-arid regions. This study investigated the responses of A. polyrhizum to drought stress and screened drought-resistant germplasms to provide a basis for the selection of high-quality germplasm resources for degraded grassland restoration. Five A. polyrhizum germplasms were collected from Longquansi Town (LQS), Hongcheng Town (HC), Zhongchuan Town (ZC), and Zhonghe Town (ZH-P and ZH-W) in Lanzhou, Gansu Province. The phenotypic and biochemical indicators were measured under the control treatment (CK) and PEG-6000-simulated drought stress treatments at -0.2, -0.6, -1.0, -1.4, and -1.8 MPa. The results showed that, with increasing drought stress intensity, the root length, shoot height, aboveground biomass, and belowground biomass of the five A. polyrhizum germplasms generally decreased, whereas the contents of soluble protein, soluble sugar, free proline, and malondialdehyde generally increased. The activities of superoxide dismutase, peroxidase, and catalase generally increased initially and then decreased, although the magnitude of these responses varied among germplasms. Two-way ANOVA showed that drought stress and germplasm had highly significant effects on all 11 measured indicators, whereas their interaction had highly significant effects on most indicators. The drought resistance coefficients of the different indicators were correlated to varying degrees. Comprehensive evaluation showed that the drought resistance of the five germplasms was ranked as ZH-W > HC > ZH-P > ZC > LQS.