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Submitted to: Crop Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/23/2006 Publication Date: 9/1/2006 Citation: Jensen, K.B., Robins, J.G., Waldron, B.L., Peel, M. 2006. Genetic variation in dry matter production and nutritional characteristics of meadow bromegrass under repeated defoliation. Crop Science 46:1948-1954. Interpretive Summary: Interest in utilizing less productive agricultural land often associated with periods of reduced irrigation, soil salinity, and low fertility, is gaining greater interest as an alternative source of forage to public grazing. Meadow bromegrass is known for its early seasonal forage production and rapid regrowth after defoliation. The objective of this study was to evaluate the potential for forage yield improvement under repeated clipping in meadow bromegrass. Based on the genetic parameters, increases in total forage production, crude protein, neutral and acid detergent fiber, and digestibility could be expected from traditional plant breeding procedures in this meadow bromegrass population. Plant selection is more efficient for digestibility on plants grown early in the season, while selection for fiber and forage production is maybe more efficient on regrowth forage later in the growing season. Technical Abstract: Interest is increasing in utilizing less productive agricultural land often associated with periods of limited irrigation, soil salinity, and low fertility as an alternative source of forage to public grazing. In 1999, 28 cloned parents and half-sib families of meadow bromegrass were planted in a randomized complete block design to evaluate genetic variation for dry matter yield (DMY) (harvests 1 to 5), forage quality under repeated defoliation (harvests 1, 3, and 5), and to investigate intercharacter correlations. Narrow-sense heritability estimates and their standard errors for DMY at harvests 2, 3, and 4 were 0.89 plus or minus 0.32, 0.59 plus or minus 0.28, and 0.53 plus or minus 0.29, respectively, However, at harvests 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 selection on 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 plus or minus 0.29, 0.47 plus or minus 0.30, and 0.71 plus or minus 0.28, respectively. Based on correlations, it seems reasonable to assume that selection for increased DMY will increase ADF and NDF and decrease CP and in vitro true digestibility (IVTD) in this population. |
