Cyanobacterial Inoculation Enhances Nutrient Use Efficiency and Grain Quality of Basmati Rice in the System of Rice Intensification

Field experiments were carried out to evaluate the influence of the system of rice intensification (SRI) and microbial inoculation, which revealed significant enhancement in the uptake of nitrogen and zinc in brown rice grain, husk, and straw. Increases of 30–60% in the soil dehydrogenase activity and the total polysaccharide content were recorded with an Anabaena-Mesorhizobium biofilm, while the N recovery efficiency was the highest (86%) with BF1–4 (cyanobacterial consortium) inoculant. Available N and zinc in soil were highly correlated with soil organic carbon and dehydrogenase activity, indicative of the significance of soil microbiological processes in nutrient availability. Based on the pooled data of two years, BF1 Anabaena torulosa recorded a significantly higher grain yield (4.86 Mg ha–1). Nitrogen fixation showed several-fold higher values in BF1–4/BF1-inoculated treatments. Inoculation with BF1–4 and biofilms (Anabaena-Trichoderma viride and Anabaena-Mesorhizobium sp.) along with only 50% N + full dose of P and K fertilizers not only led to savings of 50–60 kg of N ha–1 but also greater nitrogen and zinc uptake and localization in basmati rice grains grown under the SRI. Our investigation illustrates that microbial options can significantly contribute toward greater uptake of N and Zn, with superior efficiency-related and agronomic productivity indices.