Reproductive Barriers in Interspecific Capsicum Hybrids: A Comparative Study of F1 Interspecific Hybrids and Parental Lines

Interspecific hybridization is a powerful technique for introducing new genes into cultivated crops like Capsicum, especially to integrate desirable traits from wild relatives. A common challenge, however, is the presence of reproductive barriers that can lead to infertility in hybrid offspring. This study investigated the reproductive viability of five F1 interspecific hybrids created by crossing Capsicum frutescens and Capsicum annuum lines, comparing their performance to that of their parent plants. The experiment was designed as a Randomized Block Design, and we measured pollen fertility, seed viability, and seed germination percentage. Our analysis revealed a substantial drop in pollen fertility for all F1 hybrids, with percentages ranging from 34.00% to 57.00%, in contrast to the high fertility of the parental lines (54.99%–78.30%). This indicates significant post-zygotic barriers in the hybrids. Seed germination also showed a wide range, from a low of 8.57% to a high of 64%, reinforcing the presence of reproductive obstacles. Notably, one hybrid (IC208580 × AP-1) exhibited the highest pollen fertility, suggesting a promising level of genetic compatibility. Another hybrid (IC208580 × Pandalam local 1) displayed the most successful seed germination. Interestingly, seed viability, as determined by the tetrazolium test, remained high across all genotypes, ranging from 76% to 96%. The findings of this study confirm that reproductive barriers pose a challenge to hybridizing C. frutescens and C. annuum. Nevertheless, the identification of specific hybrid combinations with higher reproductive success, such as those evaluated in this research, offers valuable guidance for future breeding programs focused on developing improved chilli varieties with enhanced traits.