Genetic correlations between switchgrass performance in sward conditions and surrogate measures

[摘要] Switchgrass (Panicum virgatum L.) breeders use spaced-seedling plots for evaluations of biomass yield, but prior studies are ambiguous about the relationship betweenperformance in spaced plots and commercial seeded sward performance. This studyused a split-plot incomplete block design to evaluate 52 half-sib switchgrass familiesacross two years to determine the correlations among four different plot types (including seeded swards) and four individual plant traits. Plots (1.62 m2) that contained 3,6, and 18 plants had mean yields of 5.92, 8.04, and 11.06 Mg ha–1, respectively,while seeded-sward plots had a mean of 5.37 Mg ha–1. In a mixed-model analysisincluding family-, year-, and plot-type interactions with a spatial-spline correction,the largest proportion of family variance was accounted for by the main family effect(48%), while the plot type-by-family effect was only 17% of family variance. Theseresults indicate that spaced-plant plots are reasonable surrogates for biomass performance in sward conditions. Yield reliability was 0.50 across all plot types witha mean of 0.46 for individual plot types. Surrogates for sward yield varied due togenetic background of the families. Yield of families derived from the Liberty cultivar (n = 32) had genetic correlations with winter survivorship scores (0.66). Diverselowland ecotype families (n = 20) had genetic correlations with plant height andheading date. This study highlighted a major difference in performance among theplot types, specifically that seeded swards have depressed yield due to high plant density. This should encourage further research for the mechanism behind this differencein performance.

[学科分类] 农业科学（综合）