Compatibility of inter-specific crosses between Capsicum chinense Jacq. and Capsicum baccatum L. at different fertilization stages

•The most important inter-specific hybridization barrier of the cross between Capsicum chinense Jacq. and Capsicum baccatum L. was observed during embryo development.•The three-factor combinations, i.e. flowering development stage, pollen incubation period and different sucrose concentration together with specific Capsicum species gave different effects on pollen qualities and growth, where C. chinense Jacq. with particular three-factor combinations gave the highest pollen germination and pollen tube length.•To overcome the inter-specific crossing barrier, C. chinense Jacq. was considered to be used as the male parent.

Interspecific barriers have been investigated in a direct and reciprocal cross between Capsicum chinense Jacq. (‘cv. C’) and Capsicum baccatum L. (‘cv. B’). Compatibilities of interspecific cross were examined at three different growth stages, i.e. pre-pollination, pre-fertilization and post-fertilization. At pre-pollination, higher pollen germination was obtained when the pollens were collected on the blooming day and germinated immediately without storage. In addition, ‘cv. C’ gave higher percentage germination than ‘cv. B’ under most combinations of three factors, i.e. flowering development stages, pollen incubation periods and different concentrations of sucrose. In both direct and reciprocal crosses, the pollen tubes were able to grow and reached the ovules within 48 h indicating that there were no pre-fertilization barriers. For compatibility at post-fertilization, microscopic investigation of embryo development revealed normal features of embryo during various developmental stages in ‘C-selfed’, ‘B-selfed’ and ‘B/C’ resulting in mature healthy seeds. However, the ‘C/B’ embryos began to show abnormal growth patterns at the globular stage resulting in abnormal embryos in mature seeds. In conclusion, successful interspecific hybridization between C. chinense Jacq. and C. baccatum L. can be performed using the latter as the female parent.