Integrating speed breeding and genomic tools to accelerate genetic gain in chilli (Capsicum annuum L.).

Traditional breeding of chilli pepper (Capsicum annuum L.) is constrained by long generation intervals, limiting the rate of annual genetic gain. Recent advances in predictive breeding, genomic prediction, and image-based high-throughput phenotyping have created new opportunities for integrated breeding pipelines in Capsicum annuum. Speed breeding (SB) shortens the generation cycles through extended photoperiods and optimized light regimes, enabling rapid recycling of breeding populations. This review synthesizes the integration of SB with doubled haploid (DH), genomic selection (GS), and high-throughput phenotyping (HTP) to propose a crop-specific predictive breeding framework for chilli pepper improvement. Under optimized SB protocols, flowering time and seed maturation can be substantially accelerated, while DH technology enables rapid fixation of elite recombinants despite persistent genotype-dependent limitations. Genomic selection improves prediction accuracy for complex quantitative traits, including stress tolerance and disease resistance, whereas HTP platforms facilitate rapid and non-destructive phenotypic evaluation. Recent Capsicum studies further demonstrate the importance of multi-environment genomic prediction for addressing genotype-by-environment interactions in breeding programs. However, challenges including low DH efficiency, environmental sensitivity, and limited transferability between controlled and field conditions remain significant constraints. Overall, the integrated SB-DH-GS-HTP framework provides a scientifically grounded strategy for improving breeding efficiency and accelerating the development of climate-resilient chilli cultivars.