Heterosis and reciprocal effects for agronomic and fruit traits in Capsicum pepper hybrids

The selection of pure lines followed by crosses to create superior hybrids is one of the oldest strategies in crop breeding. However, in chili peppers of the Capsicum genus hybrid breeding has lagged, in part due to a lack of detailed information about the phenotypic consequences of hybridization. Here, we performed reciprocal crosses between four inbred varieties of two species of cultivated C. chinense (cv. Habanero and Biquinho) and C. annuum var. annuum (cv. Jalapen similar to o and cv. Cascadura Ikeda). We measured 31 phenotypic traits, including plant growth and yield, and 32 fruit size and shape parameters. We found large differences for agronomic and fruit traits between the genotypes, with significant heterosis and reciprocal effects for some of them. Heterosis for seed size has a strong influence on initial growth vigour. Fruit characteristics such as size and shape were impacted by hybridization, mainly interspecific, due to fertility problems. The restoration of fertility by pollination of hybrids with parental pollen was effective in modifying fruit size and shape, and differential effects depending on the pollen source used. Our results highlight how the adequate combination of parental genotypes and the optimal crossing direction can drive phenomena like heterosis, yield and fruit morphology.