Diversity among Basmati and biofortified rice genotypes for C-N assimilation and nutrient availability

The performance of four elite Basmati rice genotypes (Pusa Basmati 1692, Pusa Basmati 1509, Pusa Basmati 1718, Pusa Basmati 1), and one biofortified (CRR Dhan 311) was evaluated in terms of plant, soil nutrient and yield attributes, measured as growth, C-N assimilatory enzymatic activities, microbiological activity, PLFA and qPCR-based quantification of selected genes. Among the five genotypes, biofortified rice variety CRR Dhan 311 recorded significantly higher values in terms of leaf pigments, proteins, Fe, Zn content, as well as nitrate reductase (NR) and carbonic anhydrase (CA) activity in leaves. Basmati rice genotype Pusa Basmati 1509 recorded the highest activity of PEP carboxylase activity in both root and leaf tissues. CA activity and proteins were significantly higher in Pusa Basmati 1718. Pusa Basmati 1509 exhibited higher soil microbial biomass carbon, while PLFA-derived biomass and dehydrogenase activity were distinctly higher in Pusa Basmati 1718. Gene abundance studies of the rhizosphere soil illustrated that Pusa Basmati 1 had the highest copy numbers of nifH, cbbL and phoX, while Pusa Basmati 1718 exhibited statistically equivalent copy numbers of cbbL and highest copy numbers of nirS genes. Across the genotypes, 0.2% differences were recorded in terms of soil organic carbon. Grain yield was statistically at par among the genotypes, except for CRR Dhan 311, and ranged from 4.1 to 4.8 t ha^–1; Pusa Basmati 1509 recorded significantly higher 1000-grain weight. Principal Component Analyses delineated distinct genotypic differences and attested to Pusa Basmati 1509 and Pusa Basmati 1718 as promising genotypes for further investigations on C-sequestration.