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).

Synthesized composites were characterized through UV-spectrophotometer, XRD, SEM, EDX and FTIR analysis. SEM and EDX images confirmed surface morphology of ordinary mesoporous nano silica (mNs) and Fe & Zn embedded mNs. In XRD pattern of mNs peaks absence indicate that nano silica synthesized by sol-gel method was amorphous whereas reduced graphene oxide (rGO) synthesized in crystalline form. FTIR spectra of Zn and Fe loaded mNs and rGO showed that encapsulation of zinc and iron by mNS and rGO was successful. Results of experiment indicate, twice foliar application of 60 ppm Zn+ 30 ppm Fe through mNs (T6) and 40 ppm Zn+20 ppm Fe through rGO (T8) exhibited significantly higher economic and biological yields of both crops over conventional and Control. With increasing doses of nano zinc and iron through mNs composite capsules, significant increase in nutrients content and uptake by cabbage and cauliflower was observed in comparison to control. Whereas, increasing doses of nano zinc and iron application through rGO lead to a considerable reduction in nutrient content and thus hamper their uptake. Thus, T6 and T8 treatments were best pronounced in terms of yields, nutrients uptake and enriching biomass by iron and zinc content in cabbage and cauliflower, respectively. Compared to control, quality of cabbage head and cauliflower curd biomass in terms of Fe and Zn content, protein and phenol content were significantly more with  40 ppm Zn+20 ppm Fe (T8) and 60 ppm Zn+30 ppm Fe (T6) through  rGO and mNs , respectively. Available zinc and iron in soil was unaffected  by application of zinc and Fe through mNs and rGO in crops.