Heterosis and combining ability analysis of Phytophthora capsici induced root rot resistance and horticultural traits in Capsicum annuum

Phytophthora capsici causes severe root rot in chili crop, leading to significant global yield losses. Effective resistance screening across various environments is crucial to identify stable resistant genotypes with superior horticultural traits. This study aimed to investigate the resistance response of different chili genotypes and their crosses, along with their agronomic performance in diverse screening conditions. The controlled greenhouse environment enabled precise genotype screening, with AVPP-0206 and Turkey-1 demonstrating notable resistance. Screening under field conditions revealed high susceptibility in genotypes like A-132 and Wiz-21. Male fertile lines showed varying susceptibility, with Wiz-21 being highly susceptible, whereas AVPP-0206 and VRI-YP showed moderate resistance. Crosses involving resistant lines resulted in hybrids exhibiting moderate to strong resistance, while hybrids from susceptible lines showed high susceptibility. Heterosis estimates indicated that crosses such as A-441 × Turkey-1, A-512 × AVPP-0206, A-512 × VRI-YP, A-512 × Turkey-1, and A-512 × Turkey-14 exhibited positive commercial heterosis for fruit yield and negative heterosis for disease incidence. These crosses also showed significant specific combining ability (SCA) effects for fruit yield and disease resistance traits, which were consistent across all tested environments. These selected lines and crosses provide valuable genetic resources for breeders, offering a foundation for developing robust, high-yielding chili cultivars with enhanced root rot resistance and superior horticultural traits.