Effects of ZnO nano-particles embedded nitrogen, phosphorus and potassium fertilizer on productivity, physical grain quality and nutrient harvest indices of aromatic rice (Oryza sativa)

A field experiment on aromatic rice (Oryza sativa L.) was conducted during kharif 2018 at the research farm of ICAR-Indian Agricultural Research Institute, New Delhi, to know the effect of ZnO nano-particles [Nps; 38 nanometer (nm) mean particle size] embedded NPK fertilizer on grain yield, protein content and protein yield, physical grain quality, nitrogen harvest index (NHI), phosphorus harvest index (PHI) and potassium harvest index (KHI). The experiment consisting of 10 treatments, viz. control (0: 0: 0 N: P₂O₅: K₂O kg/ha), 7.5 g ZnO Nps/ha alone, 100% nitrogen, phosphorus and potassium (NPK), 100% NPK (120, 60 and 40 kg/ha N, P₂O₅ and K₂O, respectively) + 5 kg Zn/ha through ZnSO₄.7H₂O, 100% NPK + 5 kg Zn/ha through ZnO (Bulk, i.e. size > 100 nm), 100% NPK + 7.5 g ZnO Nps/ha, 75% NPK + 7.5 g ZnO Nps/ha, 50% NPK + 7.5 g ZnO Nps/ha, 25% NPK + 7.5 g ZnO Nps/ha and 12.5% NPK+ 7.5 g ZnO Nps/ha, were laid out in a randomized block design with 3 replications. Application of 100% NPK + 7.5 g ZnO Nps/ha registered the highest grain yield and crude protein content which was at par with 75% NPK + 7.5 g ZnO Nps/ha. Not only yield and protein content, application of 100% NPK + 7.5 g ZnO Nps/ha also recorded the highest hulling, milling and head rice recovery which were statistically similar to application of 75% NPK + 7.5 g ZnO Nps/ha. However, non-significant difference was observed among fertilizer treatments with respect to rice grain length, breadth and length: breadth of milled rice. Significant improvement in nutrient harvest indices was noticed owing to combined application of ZnO Nps with NPK fertilizers over the control. Hence, it can be concluded that application of 75% NPK + 7.5 g ZnO Nps/ha is the best option for increased productivity and nutrient-use efficiency.