Heterosis and combining ability for related traits in tomato

Tomato (Solanum lycopersicum L.) yields have continued to plummet in Kenya due to biotic stresses and reliance on low yielding varieties. This study aimed at determining heterosis and combining ability for fruit yield and yield components among tomato genotypes and select F1 hybrids combining high fruit yield and other market demanded traits under Kenyan conditions. Ten parental genotypes and their 45 F1 hybrids were studied using 10×10 half diallel mating design, excluding the reciprocals and the self’s. The experiment was set up in Kiambu and Kirinyaga Counties in Kenya. Out of 45 F1 hybrids evaluated, 89% had reduced (negative heterosis) days to 50% flowering and 11% days to maturity, compared to their better parents. Higher heterosis (-9%) was recorded on days to flowering in AVTO1429 x Cal J VF) and -5% for maturity in Roma VF x AVTO1314. All the F1 hybrids had positive heterosis for number of trusses per plant and fruit yield. F1 hybrid AVTO1429 x AVTO1314 had the highest positive heterosis of 114.39% for fruit weight per plant yield. The results showed high significant difference among the ten genotypes for general and specific combining ability effects (male x female) for all the traits evaluated. There was additive and non-additive gene action for the traits, which are important aspects in developing a tomato breeding programme.