Genomewide Selection in Rice (Oryza sativa L.) Breeding: Balancing Cost and Time for Higher Genetic Gain

In rice (Oryza sativa L.), genomewide selection and field-based rapid generation advancement (FRGA) are two ways to increase genetic gain. Our objective was to assess genetic gains from genomewide selection coupled with FRGA in a rice breeding pipeline. Per-unit breeding costs were estimated for crossing, generation advancement, phenotyping and genotyping. One- and two-cycle genomewide selection schemes were simulated and were compared with phenotypic selection via single seed descent. Results showed that two-cycle genomewide selection with FRGA achieved the largest genetic gain. This outcome was obtained with 300 Cycle 0 F₂ plants, 300 Cycle 1 F₂ plants, 100 lines in on-station yield trials, 50 lines evaluated across two locations in advanced yield trials and a predictive ability of 0.80. This gain represented 167% of the maximum gain from phenotypic selection and 141% of that from one-cycle genomewide selection. Genomewide selection schemes with FRGA reduced breeding cycle time by 15%–28% compared to phenotypic selection. Our findings suggest that two-cycle genomewide selection with FRGA is a time- and cost-efficient strategy for increasing genetic gain in rice breeding.