Efficiency of Indirect Selection for Dry Matter Yield Based on Fresh Matter Yield in Perennial Ryegrass Sward Plots

Abstract

Forage dry matter yield (DMY) is a high‐priority trait in breeding perennial ryegrass (Lolium perenne L.). However, determining dry matter concentration is highly labor intensive. For a similar level of resources, indirect selection based on fresh matter yield (FMY) would allow a greater number of replicates, genotypes, or both to be evaluated. Our objective was to estimate the efficiency of indirect selection for DMY based on FMY of pure perennial ryegrass sward plots. Over a 14‐yr period, replicated trials, containing perennial ryegrass genotypes of similar ploidy and maturity category, were sown in Ireland and assessed for DMY and FMY at each harvest over two consecutive years. Forage was generally surface dry when harvested. The estimated efficiency of indirect selection based on two replicates and comparable selection intensity was high (≥0.80). Simulation models indicated that resources would be used more efficiently by evaluating more genotypes than by increasing the number of replicates. For example, doubling the number of plots to increase the number of replicates from two to four indicated an increase in the efficiency of indirect selection from a mean 0.88 to 0.94. However, doubling the number of plots and including more genotypes, facilitating greater selection intensity, indicated an increase in the efficiency of indirect selection from a mean 0.88 to 1.04. This study indicates that FMY can be used successfully as an indirect selection method of increasing DMY in perennial ryegrass swards.

Genetic and Environmental Variation in a Commercial Breeding Program of Perennial Ryegrass

“…The decrease of residual variance in the second year may be related to a better establishment that makes the cutting conditions more homogeneous, thereby reducing the measurement error. The heritabilities estimated in this paper mostly agree with other publications in sward plots (Frandsen, 1986; Devey et al, 1989; Ravel and Charmet, 1996; Conaghan et al, 2008b). However, the estimates in this paper often appear to be more precise, due to the relatively large amount of data that were included.…”

“…The low phenotypic correlations between the same cuts in two consecutive years was also shown by Conaghan et al (2008b), who reported a small predictability for the yield in the second year based on first-year data. This result could be due to the fact that some families actually produce more in the first year and less in the second year and vice versa.…”

“…Phenotypes remained poorly correlated, because of considerable environmental effects and their interactions with genotypes, which represent the biggest components in the models. High correlations between GMY and DMY in the same cut (also shown by Conaghan et al, 2008b), together with the low permanent environmental and residual effects, may allow for indirect selection for DMY using GMY as the selection criterion. This possibility may be especially useful in smaller experiments, in which samples can be harvested under the same weather conditions, or wherever the use of drying equipment would not be cost‐effective.…”

Cell Wall Composition and Ruminant Digestibility of Various Maize Tissues Across Development

“…The ability to select for genotypes that will be higher quality at maturity based on a trait measured before flowering would increase the efficiency and rate of gain that can be made from selection on a per-year basis. Successful indirect selection has been demonstrated for various traits and crops [7,44]. In these studies, greater selection responses were observed when the heritability of the trait to be evaluated as well as the correlation between the indirect and direct targets of selection were relatively high.…”

Adjustment of Biomass Yield to a Dry Matter Basis in Switchgrass Breeding: A Necessity or a Nuisance?

“…In perennial ryegrass ( Lolium perenne L.), FMY is routinely used as the principal selection criterion for forage yield plots under both conservation and frequent‐harvest managements, owing to relationships between FMY and DMY that are similar to those observed in the current study (Conaghan et al, 2008). The Conaghan et al (2008) study similarly showed that heritability of FMY and DMY were similar and that an increase in the number of genotypes is required to allow FMY to achieve a greater rate of gain than DMY. Otherwise, for both the ryegrass and switchgrass studies, use of FMY is nothing more than a labor‐saving approach.…”