Response of Four Perennial Southwestern Grasses to Shade

A nursery plot study was conducted to determine if the observed relative abundance of Arizona cottontop, bush muhly, and plains bristlegrass under mesquite trees on native range was related to the ability of these grasses to adapt to shade. Plants of these species plus black grama which grows in open areas were subjected to shading only and shading after defoliation treatments using five levels of shade from 0 to 80%. Evaluation of morphological, physiological, and yield responses showed that all plants made their best growth in full sunlight; but Arizona cottontop, bush muhly, and plains bristlegrass displayed greater ability than black grama to adapt to shade.