Genetic Variation in Dry Matter Production and Nutritional Characteristics of Meadow Bromegrass under Repeated Defoliation

Abstract

Meadow bromegrass (Bromus riparius Rehm.) has gained interest as a highly productive pasture grass that can be used under management intensive grazing with limited irrigation. In 1999, 28 cloned parents and half‐sib families of meadow bromegrass were each planted in a randomized complete block design to evaluate genetic variation of meadow bromegrass for dry matter yield (DMY) (Harvests 1 to 6), forage quality under repeated defoliation (Harvests 1, 3, and 5), and investigate intercharacter correlations. Narrow‐sense heritability estimates and their standard errors for DMY at Harvests 2, 3, and 4 were 0.89 ± 0.32, 0.59 ± 0.28, and 0.53 ± 0.29, respectively. However, at Harvest 1 and 5, standard errors of the heritability estimates for DMY were equal to or greater than the estimates. All heritability estimates for crude protein (CP) were at least twice their standard errors at Harvests 1, 3, and 5. High narrow‐sense heritabilities at Harvest 5 for acid detergent fiber (ADF) suggest that selection on forage harvested later in the growing season might be more efficient than forage harvested earlier in the season. Combined across years and within harvests, narrow‐sense heritability estimates and standard errors for neutral detergent fiber (NDF) were 0.66 ± 0.29, 0.47 ± 0.30, and 0.71 ± 0.28, respectively. Based on correlations, it seems reasonable to assume that when selecting for increased DMY that ADF and NDF will increase and that CP and IVTD will decrease in this population.