Genetic Variability of Seed Yield and Agronomic Characters in Festuca Hybrids and Amphiploids

Abstract

Wide hybridization is a useful tool for crop improvement, but there is little empirical data concerning effects of amphiploidy on genetic variances of agronomic characters. The objective of this study was to determine genetic variances and broad‐sense heritabilities of seed yield components and winter vigor for sterile F1 hybrids and partially fertile, meiotically unstable amphiploid derivatives. Fifteen reciprocal hybrids (2n = 6x = 42) of giant fescue [Festuca gigantea (L.) Vill.] × tall fescue (F. arundinacea Schreb.), and 75 amphiploid derivatives (2n = 48 to 84), were tested. Amphiploids were chosen from five successive generations of predominantly maternal half‐sib progeny. Entries were clonally propagated, space planted, and evaluated during 2 yr for culm number, culm height, anthesis date, winter vigor score, seed yield per plant, and seed yield per panicle. Amphiploids produced an average of 70% fewer culms plant−1 than F1 hybrids. Mean seed yield of amphiploids (6.5 g plant−1) was markedly less than expected in tall fescue. Seed yield per plant and seed yield per panicle tended to change quadratically with amphiploid generations, but the response was strongly influenced by years. Genetic variances were significant (P < 0.05) for most characters in hybrid and amphiploid populations. Estimates of broad‐sense heritabilities were significant in the amphiploid population and ranged from 46% for seed yield per panicle to 81% for culm height. These results indicate that genetic variation in the amphiploids is probably sufficient for improving agronomic characters; however, aneuploidy might negate potential genetic advance of seed yield.