Estimation of Variability of Quantitative Traits in BSSS by Using Unselected Maize Inbred Lines¹

Abstract

We evaluated 247 S 6 unselected maize (Zea mays L.) lines, developed by single‐seed descent from 250 ‘BSSS’ S 0 plants, for 21 quantitatively inherited traits in 3 environments. The S 6 lines were considered representative of a random group of genotypes from BSSS for the estimation of genetic variances, heritabilities, and correlations among traits. Significant genetic variation existed among the S 6 lines for all traits. The estimates of heritabilities, on a mean basis, were high for most traits, indicating that selection would be effective in the desired direction for any of the traits measured. The estimates of the S 6 line components of variance, which were about equal to twice the additive genetic variance of the base population, were significant for all traits. After adjustments for inbreeding were made, the estimates of the genetic components obtained by use of S 6 lines were very similar to those obtained by using noninbred progenies for seven comparable traits. The genotypic and phenotypic correlations between yield and plant and tassel traits were either very small or zero. The correlations between the ear components and yield generally were higher, with kernel depth having the highest genetic correlation with yield (r G = 0.76). The only plant and tassel traits that showed a relatively high correlation were plant height with ear height (r G = 0.79) and tassel height with tassel‐branch length (r G = 0.55). The genetic correlations among the ear traits ranged from 0.33 to 0.81 and among the root traits from −0.68 to 0.61.