Nanopriming with zero-valent iron synthesized using pomegranate peel waste: A "green" approach for yield enhancement in Oryza sativa L. cv. Gonindobhog

Nanopriming is a combination of nanoparticle treatment and a seed dressing technique that can increase seed quality, seedling vigour, yield and also imparts tolerance against biotic and abiotic stress. Here, nano-scale zerovalent iron (G-nZVI) was synthesized using fruit peel waste of Punica granatum L and their formation was validated from XRD and optical spectroscopic techniques. Later, the seeds were primed with G-nZVI at six different concentrations (0, 10, 20, 40, 80, and 160 mg L-1) to determine the dose which is optimum for increasing germination percentage and seedling vigour of rice (Oryza sativa L. cv. Gobindobhog). According to initial results, upon priming seeds with 40-80 mg L-1 G-nZVI highest growth rate was found. The early growth enhancement of seedlings was chiefly attributed to increased ROS generation, higher hydrolytic enzyme activities, and increased iron uptake in germinating seeds upon nanopriming. The effects of nanopriming were carried over to later stages of development. A field experiment was carried out where nanoprimed seeds and traditional hydroprimed control seeds were sown in plots and grown till maturity without the aid of any conventional fertilizers and pesticides and it was found that crop yield and grain nutrient concentrations were higher in nanoprimed sets. Compared to control hydroprimed sets, 1.53 folds higher crop yield was observed upon seed priming with 80 mg L-1 G-nZVI. Thus in the future, G-nZVI can be considered to be a novel low-cost, ecofriendly, food waste-derived seed treatment agent that has immense potential in increasing rice yield.