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ARS Home » Pacific West Area » Logan, Utah » Forage and Range Research » Research » Publications at this Location » Publication #334182
Title: Tall fescue forage mass in a grass-legume mixture: predicted efficiency of indirect selection

Author
item Waldron, Blair
item Peel, Michael
item Larson, Steven
item Mott, Ivan
item CREECH, J. - Utah State University

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2017
Publication Date: 2/14/2017
Citation: Waldron, B.L., Peel, M., Larson, S.R., Mott, I.W., Creech, J.E. 2017. Tall fescue forage mass in a grass-legume mixture: predicted efficiency of indirect selection. Euphytica. 213:67. doi: 10.1007/s10681-017-1856-x.

Interpretive Summary: High fertilizer prices and improved environmental stewardship have increased interest in grass-legume mixed pastures. However, most grass and legume varieties are not selected for growth in a mixture. This experiment examined the efficiency of selection in a grass monoculture environment to indirectly improve tall fescue (Lolium arundinaceum (Schreb.) Darbysh.) forage mass in a grass-legume mixture. Heritability and other genetic parameters of tall fescue forage mass were estimated from tall fescue plants overseeded with either turf-type tall fescue (monoculture) or alfalfa (mixture). Monoculture performance successfully predicted mixture performance for harvests in July and October. Whereas, indirect selection in monoculture was not predictive of mixture for harvests in June, August, and annual forage mass. Moreover, low rank correlations indicated that very few top performaning families were in common between the monoculture and mixture environments within any of the harvests. Results indicate that direct selection in a mixture should be used to improve tall fescue forage performance in a grass-legume mixture.

Technical Abstract: High fertilizer prices and improved environmental stewardship have increased interest in grass-legume mixed pastures. It has been hypothesized, but not validated, that the ecological combining ability between grasses and legumes can be improved by breeding specifically for mixture performance. This experiment examined the predicted efficiency of selection in a grass monoculture environment to indirectly improve tall fescue (Lolium arundinaceum (Schreb.) Darbysh.) forage mass in a grass-legume mixture. Heritability, genetic and rank correlations, and selection efficiencies were estimated for forage mass in a tall fescue half-sib population grown as spaced-plants overseeded with either turf-type tall fescue (monoculture) or alfalfa (mixture). Heritability for tall fescue forage mass in monoculture ranged from 0.32 to 0.70 and were always similar or greater than those in mixture (range 0.27 to 0.55) for four successive harvests and annual total. Genetic correlations between monoculture and mixture tall fescue forage mass varied with values of 0.48, 0.92, -0.31, 0.70, and 0.25 in June, July, August, October, and annual total, respectively. Indirect selection efficiencies exceeded or approached direct selection for mixtures only in July and October (1.29, and 0.73, respectively). Whereas, indirect selection efficiencies were low in June, August, and annual forage mass (0.58, -0.31, and 0.28, respectively). Moreover, low Spearman's rank correlations (-0.03 to 0.35) indicated differing half-sib family performance between the monoculture and mixture environments. Results indicate that direct selection should be used to improve tall fescue forage mass in a grass-legume mixture, and support the hypothesis of increasing ecological combining ability by breeding for mixtures per se.