INHERITANCE OF LENGTH AND RATE OF GRAIN FILLING PERIOD IN SORGHUM

Abstract

The objective of the present study was to determine the modes of inheritance of length (LGF) and rate (RGF) of grain filling in sorghum. Two experiments of generation means were conducted; one involving four crosses (Wheatland-Ax22830-R, SJ7-Ax22830-R, Wheatland-Ax17667-R y SJ7- Ax22830-R) and six generations (P₁, P₂, F₁, F₂, BCP₁, and BCP₂), and another involving one cross (SJ7-Ax22830-R) and seven generations (P₁, P₂, F₁, F₂, BCP₁F₂, BCP₂F₂, and F₃ progeny). The inheritance for RGF was predominantly dominant in both experiments and crosses, whereas for LGF diverged between experiments; in one of them, both the additive and dominance effects were equally important, while additive effects predominated in the other. The crosses involving the pollinator 22830R generally expressed additive x additive or additive x additive and dominance x dominance epistatic effects, for both characters. Heterosis for RGF was high and positive (from 9.4 % to 86.8 %), whereas for LGF it was low and negative (from -2.6 % to -6.5 %). Crosses involving the 22830R line showed the highest heterosis for RGF (up to 65.5 % in one experiment and 86.6 % in the other). In all crosses and only for RGF, the means of all segregant populations were higher than the best parent performance. The F₃ progeny mean heritability for the cross SJ-7 x 22830, was high for both traits (0.68 for LGF and 0.64 for RGF), thus indicating that selection would be effective.