Development of high yielding and stress resilient post-rainy season sorghum cultivars using a multi-parent crossing approach

Modern agriculture, based on biparental crop varieties have contributed tremendously to the world's food supply. However, the strategy is also being challenged due to stagnation in yield growth, climate change, susceptibility to biotic and abiotic stresses etc. Biparental crossing, the conventional cereal breeding approach, is inherently limited in its ability to fully harness the rich genetic diversity available within a crop species. This limitation stems from the restricted number of parental lines involved, which restricts the pool of desirable traits that can be combined. In contrast, cutting-edge multi-parental crossing strategies possess immense potential for generating superior trait combinations by tapping into a vastly broader genetic pool. However, despite the several advantages of this approach, its full potential has not been adequately exploited. The existing research on the development of multi-parent advanced generation inter-cross (MAGIC) populations in crops such as rice, maize, and sorghum has primarily focused on the populations themselves, lacking robust demonstrations of the potential advantages of this approach over biparental crossing in terms of developing superior crop varieties. This study aimed to develop post-rainy season sorghum genotypes with enhanced yield potential and improved tolerance to drought, shoot fly, and charcoal rot through the utilization and demonstration of a multi-parent crossing approach. 17 founder lines were utilized to generate four 8-way crosses. The performance of the resulting progeny was systematically evaluated across multiple locations. The results revealed that the 8-way cross-derived lines exhibited remarkable superiority in both grain and stover yields, outperforming not only the 2-way and 4-way cross derivatives but also their founder parents. Notably, the 8-way cross-derived lines demonstrated substantial yield advantages of over 70% and 30% in grain and stover production, respectively, compared to the bi-parent crosses. These lines also displayed enhanced drought tolerance and improved resistance against key insect pests and diseases. Specifically, two 8-way cross-derived lines, S22086RV and S22085RV, significantly outperformed the national check cultivar CSV 29R, with nearly 70% and 60% higher grain yields, and over 30% and 15% greater stover yields, respectively. Importantly, these high-performing lines also exhibited exceptional drought stress tolerance, characterized by high transpiration rate, transpiration efficiency, shoot biomass, harvest index, and grain yield coupled with low total water use, as well as resistance against shoot fly (< 15% dead hearts) and charcoal rot (< 10 charcoal rot index). These versatile, stress-resilient lines hold immense promise as valuable genetic resources to drive further crop improvement and the development of superior post-rainy sorghum varieties. This innovative breeding strategy demonstrates significant potential for transforming post-rainy sorghum cultivation, particularly in contexts constrained by limited phenotypic diversity that impedes progress.