Establishing Promising Genotypes of Cool-Season Perennial Grasses and Legumes in Disturbed Environments
[Thesis]
Shilpakar, Chandan
Islam, Anowarul M.
University of Wyoming
2020
129
M.S.
University of Wyoming
2020
Identifying suitable species for simple and complex seeding mixtures in specific growing conditions can reduce negative impact of invasive species and anthropogenic disturbance. Field and greenhouse studies were conducted to (a) evaluate the establishment of cool-season perennial grass and legume genotypes; (b) determine interaction effects of grass-legume mixtures with planting time and conditions; and (c) assess competitive ability of cool-season perennial grasses against invasive species. Field study showed spring planting is best to establish vegetation in Wyoming conditions in both improved- and resource-poor sites. Non-native grass, particularly, tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] genotypes, contributed to higher herbage production. Cicer milkvetch (Astragalus cicer L.) performed best among legumes. Mixture of legumes with grasses had an overyielding effect. Incorporation of at least 25% of legumes in the mixture produced above average forage quality with crude protein >150 g kg-1. The greenhouse study assessed the competitive ability of basin wildrye (Leymus cinereus (Scribn. & Merr.) Á. Löve), tall fescue, and crested wheatgrass [Agropyron cristatum (L.) Gaertn.] against downy brome (Bromus tectorum L.) in three different soil sources with varying soil nutrient conditions. The results showed soil sources affected competitive ability of perennial grasses as well as invasive species (downy brome). Competitive response of perennial grasses was lower against downy brome in high soil nutrient conditions. Non-native perennial grasses had higher competitive ability against downy brome in low soil nutrient conditions. Overall, the study demonstrated tall fescue and cicer milkvetch have the potential for use in both improved and resource-poor conditions.