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

Abstract

We evaluated 247 $" 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 fl 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 0 = 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 0 = 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.Additional index words: Corn, Zea mays L., Genetic variance, Additive genetic variance, Heritabilities, Correlations of plant traits with yield, Correlations among plant and ear traits.

Direct and correlated responses to recurrent selection for grain yield in maize breeding populations

“…Increases in ear length, ear diameter, cob diameter,, kernel depth, and kernel row number associated with recurrent selection for grain yield, although usually statistically significant, were of small magnitudes (Table 21). Statistically significant correlation coefficients between grain yield and ear and kernel traits, often, have been reported (Obilana and Hallauer, 1974;Crosbie, 1976;Gama, 1976). Proportion of grain-yield variation attributable to these traits, however, is usually small and is highly influenced by genotype x environment interactions (Obilana and Hallauer, 1974).…”

“…Statistically significant correlation coefficients between grain yield and ear and kernel traits, often, have been reported (Obilana and Hallauer, 1974;Crosbie, 1976;Gama, 1976). Proportion of grain-yield variation attributable to these traits, however, is usually small and is highly influenced by genotype x environment interactions (Obilana and Hallauer, 1974). In my study, significant genotype x nitrogen and genotype X density interactions were observed for ear length (Table 23).…”

Changes in physiological traits associated with grain yield improvement in single-cross maize hybrids from 1930 to 1970

“…Tanaka and Yamaguchi (1972) previously concluded that sink size as determined by number of kernels per unit field area was a limitation to increased grain yields. Significant correlations between sink strength and grain yield also have been reported by El-Lakany and Russell (1971), Obilana and Hallauer (1974), Hallauer (1971), Crosbie et al (1978a) and Crosbie and Mock (1980). Different sink strength traits were correlated with grain yield in dif ferent maize populations, however.…”

Simultaneous selection for several agronomic characters in the BSSS2 maize population by means of selection indices

“…Root damage displayed the lowest estimates of heritability. Owens (1971) and Obilana and Hallauer (1974) also found that among the rootworm resistance characters in BSSS com populations, root damage had the lowest estimated heritability. Estimates of heritability reported by Owens (1971) for those three root characters were relatively lower than those found in this study although similar families were used, but the estimates based on lines pre sented by Obilana and Hallauer (1974) were higher.…”