Breeding meadow bromegrass for forage characteristics under a line-source irrigation design

Abstract

Production from less productive lands limited by irrigation can be increased if genetically improved pasture grasses are developed with increased dry matter production (DMY) and nutritional quality. In 2000, 18 half-sib families of meadow bromegrass were seeded in a modified strip-plot design with four replications and water levels (WL) applied as nonrandom strips ranging from 10.1 mm wk-1 at WL-5 to 36.8 mm wk-1 at WL-1. The objective was to estimate genetic variability and parameters as affected by irrigation level and harvest date for DMY, crude protein (CP), in vitro true digestibility (IVTD), neutral detergent fiber (NDF), and digestible neutral detergent fiber (dNDF). Low h2 estimates for DMY suggest that gains in total DMY from selection within these half-sib families (HSF) are not likely. Crude protein concentrations were more influenced by harvest date than WL. Heritability estimates were relatively high regardless of WL or harvest date for IVTD. The effect of WL on h2 estimates for NDF were less defined, suggesting that gains might be achieved faster if selection was done on forage harvested later in the growing season at less than optimum irrigation. Heritability estimates for dNDF were either small or associated with large standard errors. Key words: Heritability, irrigation rates, forage yield and quality, crude protein, neutral detergent fiber, in vitro true digestibility