Genetic Variances of Agronomic and Morphological Traits of Diploid Crested Wheatgrass

Crested wheatgrass breeding efforts in the USA have focused on tetraploid germplasm, resulting in little genetic information available for diploid germplasm. This study was conducted to estimate progenymean heritability (h²) of eight traits of diploid crested wheatgrass (Agropyron cristatum L.) grown under seeded competitive conditions in the northern Great Plains. Thirty half-sib families were randomly selected from a genetically broad-based population, and evaluated at one location over 2 yr, in single-row 1.5-m plots, spaced 38 cm apart, and seeded at 90 seed m⁻¹. Heritabilities based on the progeny meansof 30 families were determined for forage dry matter yield (h² = 52%), filler height (h² = 63%), first-cut vigor (h² = 15%), regrowth vigor (h² = 68%), proline content (h² = 49%), spikelets per spike (h² = 59%), anthocyanin pigmentation of stem nodes (h² = 36%), and flag leaf pubescence (h² = 70%). Heritability of forage yield, tiller height, regrowth vigor, number of spikelets per spike, and flag leaf pubescence were estimated with the greatest precision. Firstcut vigor, proline content, and node color were estimated with less precision. Proline accumulation was not associated with either dry matter yield or regrowth vigor under water stress. Regrowth vigor was not associated with first-cut yield (P ≥ 0.24), indicating that improvement in first-cut yield would have little effect on forage regrowth potential. A moderately high heritability estimate for regrowth vigor indicated that selection for this trait could extend the grazing season of crested wheatgrass. Genetic variance components for all traits except first-cut vigor exceeded their standard errors. Significant family × year effects were detected only for node color. The results indicate that evaluation over multiple years would not be needed for most traits studied. Research supported in part by USDA-CSRS grant 89-34207-4279.