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Resumo
Knowledge of maternal and paternal contributions of segregating families to yield components should be useful for generating hybrids with higher yield potential of sorghum.
Reciprocal crosses between population steriles and fertile pollinators and two A/B lines differing in seed number and seed weight were used to examine whether maternal effects on seed number and seed weight contribute substantially to grain yield. The sources of experimental material were one large-seeded parent (Wheatland inbred line), one small-seeded parent (46038 inbred line), and a range of male and female parents from the Nebraska Seed Size Population (NSSC5). Measurements from generations P1 (parent 1 = population), P2 (parent 2 = inbred line, either 46038 or Wheatland), F1, F2, BC1 (backcross 1) and BC2 (backcross 2) were obtained in two experiments, one under field conditions and another under greenhouse conditions. Traits measured were grain yield, yield components and respiration rates through the development of the plant. The genetic analyses included analysis of fixed and random effects with the Multiple Trait Derivative Free Restricted Maximum Likelihood program (MTDFREML). The analysis of random effects used pedigree and inbreeding information. The model included random direct and maternal genetic effects and cytoplasmic effects.
Results suggest that maternal effects were important for yield, seed number and seed weight. Cytoplasmic effects were more important for yield and seed number than for seed weight. Respiration rates seem to be controlled primarily by maternal inheritance. Direct genetic effects were more important for yield and seed number than for seed weight. When the model includes maternal and/or cytoplasmic effects, estimates of direct genetic variance were usually reduced.
