Synthesis of Mesoporous Silica and Graphene-Based FeO and ZnO Nanocomposites for Nutritional Biofortification and Sustained the Productivity of Rice (Oryza sativa L.)

Abstract

Considering nutrient delivery and micronutrient use efficiency problems, mesoporous nanosilica (mNs) and reduced graphene oxide (rGO)-based iron and zinc nanocomposites were formulated. Prepared nanocomposites were characterized for FTIR spectroscopy, XRD, FE-SEM, HR-TEM, and AAS to examine surface functional groups, morphology, and structural composition. XRD spectrum confirmation with SAED image of nanosilica and graphene oxide nanocomposites confirms the polycrystalline and crystalline nature with 30-70-nm crystal size. The SEM revealed that the modified surface of mesoporous nanosilica and reduced graphene oxide are well-distributed clusters and are composed of targeted micronutrients. The impact of nano Fe and Zn foliar application was evaluated on rice grain fortification, productivity, and micronutrient use efficiency. The iron and zinc uptake at 60 days after sowing (DAT) and at harvest was significantly increased with foliar application of mNs and rGO-based Zn at 30 ppm + Fe at 5 ppm nanocomposites as well as led to nutrient fortification by increasing grain uptake and content, with the application of 30 ppm zinc and 5 ppm iron through mNs resulted in an improvement of the rice grain yield by 53% over conventional fertilization. Besides significant increment in grain yield, foliar application of mNs and rGO-based nanocomposites (Zn at 30 ppm + Fe at 5 ppm) increased the Zn and Fe use efficiency by 527 and 380%, respectively, over conventional micronutrient fertilization (ZnSO4 and FeSO4).