Cross-Compatibility and Combining Ability Between Solanum Aethiopicum With its Close Relatives

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Uganda Christian University
This study elucidated the reproductive barriers and combining ability effects for yield and yield related traits in crosses between S. aethiopicum and its relatives. Six parental lines of S. aethiopicum (Shum and Gilo) and its relatives (S. incanum, S. macrocarpon, S. anguivi) were examined. Anthesis, anther dehiscence, stigma receptivity, pollen viability, fruit, seed set and F1 viability were assessed. Determining mode of gene action and combining ability, 15 successful F1 hybrids obtained from a full diallel mating design were evaluated. Overall mean number of open flowers was highest (13) for N11 and least (3) for E12, though, differed significantly (p<0.001). Stigma receptivity differed significantly among genotypes and seasons (p<0.001) and was highest for N11 at 3.31± 1.32 and least for In1 at 2.24±1.27. All genotypes had high pollen viability (µ> 80%) though differed significantly (p<0.01). All genotypes exhibited self-compatibility to varying degrees with N11 showing the highest fruit success (67.93%), seed per fruit (n=82) and F1 germination (79%). Interspecific crosses where S. macrocarpon, S. anguivi and S. incanum were used as females showed poor or no fruit and seed. N11was the top performer as a female with the cross with S. macrocarpon (N11xE12) showing highest fruit success (65.89±26.48), S. anguivi (N11xA1) showing the highest seed set (n=56±34.23) and S. incanum (N11xIN1) showing the highest F1 germination (64±18.72). High broad sense heritability (above 80%) was observed in all successful crosses for leaf and fruit traits. Specific combining ability effects were highly significant for all the traits measured (P<0.01); showing that traits were conditioned by non-gene additive action. S. aethiopicum can be selected as a female parent in crosses involving S. incanum and S. macrocarpon for raising fertile hybrids. Species with good breeding value and promising specific crosses provide a guide in establishment of breeding program for the crop.
Masters dissertation.