Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 8/8/2006
Publication Date: 11/12/2006
Citation: Conaghan, P., Casler, M.D., O-Keily, P., Downey, L. 2006. Potential use of fresh weight yield as an indirect selection method for dry matter yield in Lolium perenne L. [abstract]. ASA-CSSA-SSSA Annual Meeting. Abstract 73-1. Interpretive Summary: Breeding and evaluating new grass varieties for increased forage yield requires the evaluation of tens of thousands plots over a relatively short time span. This is further magnified by the need to harvest each plot many times over the duration of any particular trial. Determination of dry matter content on all plots is a severe limitation to the number of plots or families that can be evaluated. This study reports on the use of fresh-weight yields as a substitute for dry-matter yields, demonstrating a high correlation between the two yield measurements over a series of perennial ryegrass trials under two different management regimes. The results indicate that ryegrass breeders can improve dry-matter yields without measuring dry matter content on a routine basis. These results will be of value to other forage grass breeders.
Technical Abstract: Dry matter yield (DMY) is a high-priority trait in breeding perennial forage grasses. Selection for increased DMY involves some form of family selection across replicated plots. Sampling plots for dry matter determination is highly labor intensive, particularly for multiple cuttings within a season. Indirect selection on fresh weight yield (FWY) would be easier, quicker and less expensive to evaluate, allowing a greater number of genotypes/environments/replicates to be assessed. Over a 10-yr period, monoculture swards (6 m x 1.5 m) of Lolium perenne L. sown at Oak Park Research Centre were each assessed for DMY and FWY at each cut over a 2-yr period. Two management regimes were imposed: simulated grazing (eight cuts/yr) and conservation (four cuts/yr). Each regime consisted of 150 trials (mean 20.7 families/trial) arranged in a randomized complete block design with two replicates. With few exceptions, the phenotypic correlation coefficient between DMY and FWY was positive. Correlations for annual yield averaged across both evaluation years of the simulated grazing and conservation regimes were 0.84+/-0.01 (simulated grazing) and 0.78+/-0.01 (conservation) and at least 0.84+/-0.01(simulated grazing) and 0.72+/-0.02 (conservation) for each harvest. The top 5 genotypes with the highest annual DMY within each trial, based on means over 2 blocks, were defined as the “correct” selections. On this basis, the number of “correct” selections at each cut based on FWY averaged 3.9 and 3.4 for the simulated grazing and conservation regimes, respectively. Corresponding numbers of “correct” selections for mean annual yield were 3.5 and 3.3. These findings suggest that FWY offers an effective indirect selection criterion for DMY in breeding perennial ryegrass populations within a relatively narrow maturity range.