Analysis of seed vigor and use of different grass species in ecological restoration of expressway in Gannan, China

To provide suggestions for the selection and use of suitable grass species in the ecological restoration of an expressway on Qinghai-Xizang Plateau within Gannan Tibetan Autonomous Prefecture. We studied the seed germination characteristics of nine gramineae species, which included three ecotypes of Festuca sinensis harvested from Qinghai, Gansu, and Ningxia, Elymu snutans, Poa annua, Bromus inermis, Achnatherum splendens, Festuca rubra, Achnatherum inebrians, and four legumaceae species including Melilotus officinalis, Trifolium pratense, Coronilla varia, and Astragalus adsurgens) . On the basis of different germination indices, F. sinensis, E. snutans, P. annua, and F. rubra were planted in abandoned soil (black soil and deep loess soil) collected from a road construction area in Zhuhe, Gannan. The seeds were planted in different seasons (June and September) with different additives (microbe, plant ash, and a combination of microbe and plant ash). The results showed that only F. sinensis harvested from Gansu and Ningxia, as well as A. inebrians, T. pratense, and C. varia, had seed germination rates above 60%, whereas the germination rates were relatively low for the other eight grass species. In addition, the germination forces of A. inebrians, T. pretense, and C. varia seeds were substantially higher than those of the other seeds (P < 0.05), and the germination indexes of A. inebrians and A. adsurgens seeds were significantly higher than those of the other seeds (P < 0.05). The seed vigor indexes of three ecotypes of F. sinensis A. inebrians, T. pretense, and A. adsurgens were higherthe highest. F. sinensis harvested from Qinghai and E. nutans had considerable longer plumule and radicle lengths as well as higher seedling water content than the other grasses (P < 0.05). Both soil and additive types significantly influenced seed germination and the growth of the four grasses (P < 0.05). Surface black soil was more suitable for growing the four species, and the addition of plant ash was beneficial to plant growth. These results provide a theoretical and practical basis for the reasonable planting of native grasses when constructing highways in alpine regions.