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Breeding for “weed competitive” cultivars is a prioritized goal under direct seeded rice (DSR) conditions for achieving higher grain yields. Early seedling vigour (ESV) is an imperative trait that imparts weed competitiveness through initial rapid growth and uniform crop establishment. African rice species Oryza glaberrimahas been recognised as potential donors for weed competitive traits due to their early vegetative vigour. In the present study, 29 accessions of O. glaberrimawere evaluated for early seedling vigour traits under laboratory and DSR conditions. Seedling vigour index-I and II estimated from the paper roll method under laboratory condition revealed that six O. glaberrimaaccessions (EC861796, EC861801, EC861804, EC861814, EC861819 and EC861820) had higher/similar seedling vigour indices than high vigour check Sabita. In addition, during Kharif2017 and Rabi2018, O. glaberrimaaccessions were phenotyped for nine ESV traits, e.g.seedling height, number of leaves/tillers, leaf area, shoot fresh/dry weight, absolute growth rate, specific leaf area and crop growth rate under DSR condition. Significant genetic variation and genotype × environment interaction was observed for ESV traits under DSR condition. The heritability estimates for ESV traits were ranging from low to high, indicating complex inheritance of the trait. The study identified six accessions of O. glaberrima(EC861787, EC861790, EC861792, EC861795, EC861819 and EC861820) as promising accessions with early seedling vigour based on mean performance in both seasons under direct seeded rice condition. Thus, our study demonstrated inherent nature of early seedling vigour in O. glaberrimaand these promising accessions could be exploited for breeding weed-competitive rice cultivars.

Soil phosphorus (P) deficiency is a major constraint on rice productivity. Identifying donors with better uptake and yield under low soil P is crucial for rice breeding programs. To identify novel rice lines with Pup1QTL that confer tolerance to P deficiency, 143 rice lines were molecularly characterized using three dominant Pup1gene-specific markers, K46-1, K46-2, and K46-K. Thirty-seven lines with Pup1QTLs were further validated using a co-dominant marker, K20-2. The following rice lines were confirmed to have the K20-2 allele: Phoudum, Sangsangba, Moirangphou, Punshi, Heitup-Phou, Kumbi-Phou, Phougak, Wangoo-Phou, Moirangphou-Yenthik, Ayangleima, Heimang-Phou, Kakcheng-Phou, MoirangPhou-Angouba, Phouren-Amubi, KJ-216, KJ-219, KJ-222, TI-15, TI-19, Vandana, NPS-53, NPK-43, SM-686, PB-4, PB-5, Sabita, DRR Dhan-41, and ASG-126. The highest percentage of tolerant alleles (represented as ‘+’) for K46-2 was 67.13%, followed by K46-K at 53.84%, K46-1 at 38.46%, and K20-2 at 20.97%. The lines showing the presence of both dominant and co-dominant markers were evaluated for root length, shoot length, and root volume at the maturity stage under irrigated low soil P field conditions in relation to soil P uptake and growth. Among the evaluated lines, Ayangleima and Keibi-phou had higher root lengths, while Kakcheng-phou and TI-17 had higher root volumes than the checks. These lines could be further explored to understand the uptake and efficiency mechanisms under low soil P conditions.