Genetic analysis and selection experiment for narrow-sense earliness in wheat by using segregating hybrid progenies

Genetic analysis of narrow- sense earliness in wheat was carried out, by using four segregating populations derived from the crosses between five cultivars with a large variation in narrow-sense earliness. Narrow-sense earliness measured at 15 °C, exhibited a large variation among five parental cultivars ranging from 29.8 to 51.2 days. It was earlier in F₁ hybrids than in the mid-parent and later by a few days than in the early parent in all cross combinations, indicating the partial dominance of earliness. The polygenic nature of narrow -sense earliness was indicated by continuous variation in F₂ populations, and heritability in a broad sense ranged from 0.90 to 0.99 among four F₂ populations. In randomly selected progenies, the parent-offspring correlation coefficient between parents (F₂ plants) and F₃ lines proved to be statistically significant (r=0.6080.742, P<0.01). These results indicated that narrow-sense earliness is a highly heritable character, inspite of its quantitative nature. Artificial selection in F₂ populations resulted in significant improvement in early and late selections as compared with randomly selected F₃ lines, indicating the effectiveness of artificial selection for optimizing narrow-sense earliness.