Nano-fertilizer formulations differentially affect growth, nutrient uptake, yield, and grain quality of rice

Introduction In this study, five nano-fertilizer formulations (Nano-P, Nano-Zn, Nano-NPK, Nano Micro Mix, and Agrosatva) were evaluated for their effects on growth, physiology, grain quality, and elemental composition of the salinity-tolerant rice cultivar Panvel 1 under the System of Rice Intensification. Methods A randomized complete block design with three (lab analysis) and five replications (field analysis) was implemented. Foliar applications were administered at tillering and panicle stages and compared with an unfertilized control. Results and discussion Data were analyzed using ANOVA followed by Tukey’s HSD test (p ≤ 0.05). Nano-NPK significantly increased vegetative growth at tillering, resulting in the tallest plants (94.3 ± 1.6 cm) and longest roots (37.7 ± 2.3 cm) compared with the control. Nano-Zn produced the highest early biomass (fresh weight 137.1 ± 2.1 g; dry weight 67.5 ± 1.5 g) and markedly enhanced guaiacol and syringaldazine peroxidase activities, indicating improved oxidative defense. Nano-P consistently maintained the highest net photosynthetic rate across both stages and reduced the accumulation of FTIR spectra associated with stress-responsive functional groups. At the panicle stage, Agrosatva resulted in the greatest plant height (125.2 ± 2.4 cm) and supported superior grain nutritional quality, increasing crude protein from 1.63% ± 0.12% in the control to 5.05% ± 0.43% and starch from 77.83% ± 0.08% to 79.91% ± 0.48% (both p ≤ 0.05). ICP-MS profiling demonstrated that all nano-treatments reduced leaf arsenic by 15%–35% and sodium by 71%–83%, with Agrosatva providing the most balanced enrichment of macro- and micronutrients. Nano micro Mix (N-MM) maximized reproductive branching, increased chlorophyll a and enzyme activity at key stages, and elevated grain fat and protein content. Nano-NPK produced the highest levels of photosynthetic pigments, including total chlorophyll, and balanced vegetative growth. Agrosatva exhibited the most balanced elemental composition, accompanied by N-MM, Nano-P, and Nano-Zn, in the stage-dependent regulation of the thylakoid protein complexes (PSI, PSII, and LHCII), thereby optimizing light-harvesting apparatus assembly across growth phases. These findings indicate that nano-fertilizers represent a feasible and sustainable option for rice cultivation, offering enhanced nutritional value, improved stress tolerance, and reduced heavy-metal uptake under the tested conditions using the Panvel 1 variety.