Estimates of Genetic Parameters in Switchgrass¹

Abstract

A population of switchgrass, Panicum virgatum L., consisting of 33 half‐sib families was investigated over 2 years to obtain estimates of genetic parameters for several agronomic and nutritive traits, including height, maturity, dry weight, in vitro dry matter disappearance (IVDMD), and percent N. Dry weight was less heritable than other traits, with an individual narrow‐sense heritability of only 0.25. Narrow‐sense heritability for dry weight calculated on a family mean basis was 0.59. Dry weight and IVDMD were not significantly correlated while the correlation between dry weight and percent N was highly negative. Maturity was also negatively correlated with dry weight. The IVDMD and percent N, both measures of forage quality, had family narrow‐sense heritabilities averaged over three measurements per year of 0.79 and 0.74, respectively. Mean values for both traits were highest early in the season and declined markedly with maturity. The IVDMD and percent N were not significantly correlated. The estimated genetic parameters were used to form several selection indices involving three traits: dry weight, IVDMD, and percent N.