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Developmental morphology and forage quality relationships in perennial forage grasses
Abstract
A study at Mead, NE on a Sharpsburg silty clay loam (Typic Argiudoll) and Manhattan, KS on a Wymore silty clay loam (Aquic Argiudoll) measured the tiller demographics and leaf area index (LAI) of intermediate wheatgrass (Thinopyrum intermedium (Host) Barkw. & D. R. Dewey), smooth bromegrass (Bromus inermis Leyss.), switchgrass (Panicum virgatum L.), and big bluestem (Andropogon gerardii Vitman), predicted the developmental morphology and forage quality of switchgrass and big bluestem, and determined the relationship between in situ rumen protein degradation and developmental morphology of intermediate wheatgrass, smooth bromegrass, switchgrass, and big bluestem. Tillers were hand-clipped at ground level at 1 to 2-wk intervals, and mean stage count (MSC), mean stage weight (MSW), tiller demographics, and forage quality determined. Tiller demographics of intermediate wheatgrass and smooth bromegrass was variable across years, whereas switchgrass and big bluestem were more uniform. The variability in intermediate wheatgrass and smooth bromegrass tiller demographics reiterates the importance of initial grazing when vegetative tillers are present to optimize livestock selection. Linear day of the year equations accounted for 96% of the variation in switchgrass MSC, and illustrated the strong photoperiod sensitivity of switchgrass. Quadratic growing degree day (GDD) equations accounted for 83% of the variation in big bluestem MSC, indicating big bluestem management recommendations could be based on GDD. Morphological development accurately predicted switchgrass and big bluestem forage quality in many instances. However, GDD or day of the year were typically better predictors of switchgrass and big bluestem forage quality. The greatest utility in collecting standardized morphology data may be in communicating precise population growth stage data rather than qualitative maturity estimates. Rumen degradable protein decreased as MSC increased for all species. Escape protein (percent of crude protein) for cool-season grasses was generally lower than for warm-season grasses. Escape protein typically decreased as MSC increased for warm-season grasses. Escape protein corrected for acid detergent insoluble N and microbial protein was relatively constant across maturities within each perennial grass species.
Subject Area
Agronomy|Botany|Range management
Recommended Citation
Mitchell, Robert Brent, "Developmental morphology and forage quality relationships in perennial forage grasses" (1995). ETD collection for University of Nebraska-Lincoln. AAI9600747.
https://digitalcommons.unl.edu/dissertations/AAI9600747