Nano materials can be used in producing more soluble and diffusible sources of Zn fertilizers. Higher specific surface area and reactivity of ZnO-NPs compared to bulky ZnO may improve Zn solubility, diffusion in soil and hence better Zn availability to plants. Nano-fertilizers can supply essential nutrients for plant growth, have higher use efficiency and can be delivered in a timely manner to a rhizospheric target or by foliar spray.
Objective: To evaluate the effectiveness of different concentrations of ZnO-NPs on plant growth attributes, grain yield and final Zn levels in rice crop compared with conventional delivery of Zn.
Methods: Solution culture and greenhouse experiments were carried out to study the impact of ZnO-NPs with a mean particle size of 30 nm on rice plant growth traits, Zn concentration and yield. For comparative study, different concentrations of ZnO-NPs were used as compared to conventional ZnSO4. 7H2O (10 mg/kg) fertilizer and control (no Zn).
Results and Discussion: The highest root and shoot length, dry weight and grain yield was recorded with the application of nanoscale ZnO at 10 mg/kg which shows higher growth and yield differed from that of ZnSO4 and control thus confirming better interaction between nanoparticles and rhizosphere. The highest germination percentage of 91.7 was observed when the rice seeds were treated with the nanoscale ZnO at 100 mg/kg; and it was significantly more than that of control and ZnSO4. Higher doses of ZnO nanoparticle had negatively influenced the plant growth and yield parameters. The delivery of Zn through ZnO-NPs resulted in positive effect on seed germination, root and shoot growth, seedling vigour index, number of tillers, had higher chlorophyll content, Zn concentration and grain yield. Application of ZnO-NPs supplied Zn, had higher use efficiency, better plant growth and significantly improved the yield.
Conclusion: Delivery of Zn nutrient through ZnO nanoparticles in right dose, right time and of the right size could be effective and beneficial in enhancing the growth and yield attributes of rice crop. There is a possibility of reducing dose of Zn using nanostructured fertilizer like ZnO- NPs.
Keywords: Zinc oxide nanoparticles, Rice, Zinc uptake