Evaluation of warm‐season grasses nutritive value as alternatives to cool‐season grasses under limited irrigation

Abstract

AbstractThe production of cool‐season grasses is limited by their photosynthetic inefficiency during the hot summer months. Therefore, a study was conducted during 2006 and 2007 at a Logan, UT, USA field site to determine the potential of various warm‐season grasses as alternatives to cool‐season grasses during summer under limited irrigation. The study included 20 environments, which corresponded to combinations of the 2 years, two harvest dates (June and July) and five irrigation levels. There were differences among the 27 varieties (21 warm‐season and six cool‐season) for crude protein (CP), in vitro true digestibility (IVTD), neutral detergent fiber (NDF), neutral detergent fiber digestibility (NDFD), water soluble carbohydrates (WSC) and biomass (BM) across the 20 environments. However, the overall variety effects were ameliorated by the presence of genotype by environment interaction for CP, WSC, BM, and to a lesser extent IVTD. The cool‐season grasses generally possessed higher trait values in each environment, yet there were several warm‐season grasses, such as big bluestem (Andropogon gerardii Vitman) variety ‘Bison’ and switchgrass (Panicum virgatum L.) variety ‘Trailblazer’ that possessed higher values for the nutritive value traits. Additionally, these warm‐season grass varieties possessed substantially higher BM than any cool‐season grass varieties. Thus, there are warm‐season grass varieties that combine high BM and higher nutritive value in the summer months under limited irrigation. These may prove to be viable forage alternatives to the cool‐season grasses during the summer slump period.