Genetic potential of S0 upland rice populations for early flowering and yield under recurrent selection

Abstract

Abstract Upland rice (Oryza sativa L.) production requires cultivars that combine early flowering, high grain yield, and market-acceptable grain. Since flowering time and yield are quantitative traits, recurrent selection is an effective breeding strategy. This study aimed to identify superior populations from the first cycle (CI) of the upland rice recurrent selection program for early flowering and high yielding. 21 S 0 populations from CI and two commercial cultivars were evaluated in a randomized complete block design with three replications. Agronomic and grain quality traits, and a multi-trait Z-index were assessed. Diallel analysis estimated general and specific combining ability. Six S 0 CI populations showed superior multi-trait performance. Parents G1 and G5 contributed the highest frequency of favorable alleles across key traits. The hybrid combinations G1 × BRSMG Caçula and G5 × G6 showed the greatest genetic complementarity. These results confirm the effectiveness of recurrent selection for improving earliness and yield in upland rice.