Expression of heterosis in floral traits and fruit size in tomato (Solanum lycopersicum) hybrids
The present research was prompted by lack of improved tomato cultivars adapted to the humid tropical. Tomato hybrids were developed by crossing wild and cultivated tomato varieties. The average fruit size of the tomato hybrids generated did not meet the level of acceptability in the local market. A modified three way cross between the advanced generation of the tomato hybrids and an exotic variety with giant fruit size was initiated. The resulting hybrids were evaluated to determine the magnitude of heterosis in floral traits and fruit size. Highly significant differences were observed among the genotypes in all the traits studied. Highly significant heteroses were found for flower length which ranged from 2.7 to 13.4% and 7.2 to 21.9%, style length 2.6 to 14.5% and 6.8 to 43%, fruit length 1.9 to 5.1% and 4.6 to 27.4% over the better and mid parents, respectively. Similarly, a significant positive heterosis was recorded for ovary area which ranged from 1.2 to 6.2%, ovary perimeter 1.6 to 6.2%, ovary length 4.8 to 15.3%, fruit diameter 5.7 to 6.5% and number of fruits per plant 14.56 to 55.195% over mid parents only.
Key words: Heterosis, floral traits, modified three way cross, tomato, Solanum spp