Introgression of Yield Component Traits in Rice (Oryza sativa ssp. indica) through Interspecific Hybridization

Considering the potentials of wild rice (Oryza spp.), as well as the need to enhance the yield potential of rice and to increase rice production to meet increasing demands, 1780 backcross inbred lines (BILs) were generated by crossing 70 accessions of six “AA” genome species: Oryza glaberrima Steud., Oryza barthii A. Chev., Oryza nivara Sharma & Shastry, Oryza rufipogon Griff., Oryza longistaminata A. Chev. & Roehr., and Oryza glumaepatula Steud. with two elite cultivars of Oryza sativa L. The wild species accessions were selected based on variation at the DNA markers and agromorphological traits. The BILs were generated by backcrossing F₁s twice (thrice in some cases) to recipient parents, followed by continuous selfing and selection for the yield and yield component traits. The set of 1780 BC₂F₅ to BC₂F₁₀ BILs were evaluated in an augmented design over 3 yr. Based on ANOVA in augmented design, 108 agronomically superior BILs were selected and evaluated in randomized complete block design. Of the 108 BILs evaluated, 15 BILs showed >10% yield superiority over the recurrent parent, with spikelet per panicle and thousand-grain weight as most significant traits contributing to yield increase. Based on the contribution of donor accessions for the improvement of yield component traits, six accessions of O. glaberrima, one of O. barthii, two of O. nivara, two of O. rufipogon, and one each of O. longistaminata and O. glumaepatula were identified as potential donors that could be used more rigorously in transferring genes to cultivated rice. The BILs generated in the present study represents a reservoir of novel genetic variation.