Predicted Efficiency of Spaced‐Plant Selection to Indirectly Improve Tall Fescue Sward Yield and Quality

Abstract

The validity of spaced‐plant evaluation to determine sward performance of forage grasses has been questioned. This experiment studied the efficiency of spaced‐plant evaluation to indirectly improve sward yield and nutritional quality in tall fescue (Festuca arundinacea Schreb.). Narrow‐sense heritabilities, genetic and rank correlations, and indirect selection efficiencies were estimated for a tall fescue population grown in spaced plant and seeded sward environments. Heritability for yield was similar between spaced plants and swards (0.43 and 0.44, respectively), but genetic correlation between the two was low (0.37 ± 0.38). Inconsistency (r = 0.30, P = 0.17) in family ranking further suggested that spaced plants were not predictive of sward yield. Heritability of crude protein from swards was low (0.27 ± 0.25) compared with 0.77 ± 0.08 from spaced plants, but there was no genetic relationship between the two (r = −0.13 ± 0.30). Moderate to high heritabilities and genetic correlations were observed for most fiber traits, but indirect selection efficiencies and rank correlations of <1.0 suggested that evaluation in a sward environment would be best to select for improved nutritional quality. Spaced‐plant evaluation appears to be less effective, or ineffective, at improving sward yield and nutritional quality in tall fescue. New techniques are needed that maximize genetic expression but simulate actual sward production of forage grasses.

Breeding for Biomass Yield in Switchgrass Using Surrogate Measures of Yield

“…This conclusion, derived from numerous observations on a wide range of species [e.g., [49][50][51][52], is supported by the results of the present study. The correlations between sward-plot biomass yield, row-plot biomass, and spacedplant biomass were all positive and low, indicating that each of these three traits can be used to make progress toward improving sward-plot biomass yields.…”

Quantitative trait locus mapping of genomic regions controlling herbage yield in perennial ryegrass

“…Early generation selection in forage grasses, permitting selection of specific recombinants, is routinely conducted in spaced plant formats in which plant densities are lower than those of a pasture sward. The efficacy of spaced plant evaluations for predicting yield outcomes in a sward has been challenged (Lazenby & Rogers 1964;Hayward & Vivero 1984;Waldron et al 2008) but not unanimously, with some studies showing positive relationships between spaced plant herbage yield and sward yield (Fujimoto & Suzuki 1975;Burton 1985;Humphreys 1989). The current experiment used spaced plant format and may be subject to these criticisms but there are experimental features that mitigate those concerns.…”

“…55, No. 3, September 2012, 263Á281 with confounding factors such as genotypeby-environment (G )E) interactions on phenotypic evaluation (Jafari et al 2003;Conaghan et al 2008), potential inadequacy of spaced plant data in phenotypic selection (Hayward & Vivero 1984;Waldron et al 2008) and the influence of biological inherent properties of perennial ryegrass including self-incompatibility and perenniality, are all likely contributors to the moderate rate of gain achieved through conventional breeding.…”

Evidence for Heterosis in Italian Ryegrass (Lolium multiflorum Lam.) Based on Inbreeding Depression in F2 Generation Offspring from Biparental Crosses

“…The results of the present study suggest that selection of high-yielding individual Italian ryegrass genotypes from a spaced plant nursery cannot guarantee high-yielding progeny populations in a competitive sward condition. Spaced plant evaluation was also found to be unpredictive of sward yield in tall fescue [21].…”