Abstract
There is an urgent need to breed dry direct-seeded adapted rice varieties in order to address the emerging scenario of water–labor shortage. The aim of this study was to develop high-yielding, direct-seeded adapted varieties utilizing biparental to multiparental crosses involving as many as six different parents in conventional breeding programs and 12 parents in genomics-assisted breeding programs. The rigorous single plant selections were followed from the F2 generation onwards utilizing phenotypic selection and quantitative trait locus (QTL)/gene-based/linked markers for tracking the presence of desirable alleles of targeted QTL/genes. In conventional breeding, multiparent lines had significantly higher yields (2,072–6,569 kg ha−1) than the biparental lines (1,493–6,326 kg ha−1). GAB lines derived from multiparent crosses had significantly higher (3,293–6,719 kg ha−1) yields than the multiparent lines from conventional breeding (2,072–6,569 kg ha−1). Eleven promising lines from genomics-assisted breeding carrying 7–11 QTL/genes and eight lines from conventional breeding with grain-yield improvement from 727 to 1,705 kg ha−1 and 68 to 902 kg ha−1, respectively, over the best check were selected. The developed lines may be released as varieties/parental lines to develop better rice varieties for direct-seeded situations or as novel breeding material to study genetic interactions.
Highlights
Rice is mainly cultivated under anaerobic conditions and primarily adapted and evolved under these conditions (Kumar and Ladha, 2011)
The stringency of selection can be estimated from the number of plants/breeding lines selected across generation advancement, as represented in Supplementary Table 2
The study showed genomics-assisted breeding (GAB) was a better strategy for improving yield and adaptation of rice under dry direct-seeded rice (DDSR) utilizing multiple quantitative trait locus (QTL)/genes compared to conventional breeding
Summary
Rice is mainly cultivated under anaerobic conditions and primarily adapted and evolved under these conditions (Kumar and Ladha, 2011). A shortage of water and labor input makes rice production through transplanted rice (TPR) more expensive, less profitable, and unsustainable (Farooq et al, 2011). The estimates specify that the water requirement for irrigation by 2025 could be approximately 561 km for a low-demand scenario and 611 km for a high-demand scenario (Kumar et al, 2005). Genomics-Assisted Breeding for Direct-Seeded Rice rice grown and consumed in Asia and the large water requirements of conventional transplanted rice cultivation systems, it is evident that this water scarcity will severely affect rice production in this continent. The water scarcity situation will lead to rice cultivation with less water (Wang et al, 2002)
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