Compatibility Barriers Affecting Crossability Between Solanum aethiopicum and Its Relatives

Abstract

Reproductive barriers are single most important impediment in conventional breeding of Solanum aethiopicum (Shum and Gilo) and its relatives. This study investigated compatibility barriers between S. aethiopicum and its relatives. A randomized complete block design and a full diallel mating method were used to evaluate floral phenology and compatibility of six genotypes at different floral stages. Parameters assessed include; anthesis, anther dehiscence, stigma receptivity, among others. Results showed that most flowers in anthesis per genotype were counted at 8:00am. Overall mean number of open flowers differed significantly (P<0.001) and was highest for N11(n=13) and least for E12(n=3). Anther dehiscence varied significantly (P<.001) among floral stages. However, there was no difference among genotypes. All genotypes showed high pollen viability (> 80%) although they differed significantly (P<0.01). Stigma receptivity averaged highest (3.31) for N11 and least (2.31) for In1. All genotypes exhibited self-compatibility; N11 averaged highest for fruit set (67.93%), seed per fruit (82) and F1 germination (79%). Crosses revealed moderate compatibility (50%); highest fruit were in N4xN11 (71.97%), seed N11xA1 (56) and F1 germination inN11x N4 (76.3%) respectively. In the crosses where In1 was a female parent 80% incompatibility was observed at fruit set whereas73% of crosses where E12 was a female parent set fruits without seed. Female functioning may be a major factor in observed incompatibility between S. aethiopicum and its relatives. To harness the potential of S. aethiopicum relatives, N11 and N4 can be advanced as female parents in wide hybridizations.