Nano-sized ZnO enhances photosynthetic parameters, yield and Zn content in rice (Oryza sativa)

A pot culture experiment was conducted during rainy (kharif) season of 2021 at ICAR-Indian Institute of Rice Research, Hyderabad, Telangana to study the influence of the foliar application of various Zn sources such as nano ZnO, bulk ZnO, and ZnSO4 on rice crop. The experiment was laid out in a completely randomized design (CRD) with the following treatments, containing 3 concentrations of bulk ZnO (500 mg/litre, 1000 mg/litre, and 1500 mg/ litre), 3 concentrations of nano ZnO (50 mg/litre, 100 mg/ litre, and 150 mg/litre), 0.5% ZnSO4 and control with 3 replications. The findings revealed that ZnO nanoparticles (NPs) positively impacted rice grain yield, dry matter accumulation, and Zn content. Compared to the control (no zinc), ZnO NPs (150 mg/litre) and standard ZnSO4 treatments exhibited the highest plant height (83.3 cm and 73.7 cm, respectively), grain yield (5.97 g/pot and 6.03 g/pot), and straw yield (7.82 g/pot and 7.94 g/pot). The increased photosynthetic substances and higher dry matter accumulation throughout the rice growth stage contributed to the enhanced grain yield. Furthermore, supplementing Zn via nano ZnO (150 mg/litre) and 0.5% ZnSO4 resulted in significant Zn enrichment: 33,35; 77,87 and 21, 28% in straw, grain and soil, respectively over control plants. This study effectively demonstrates that ZnO nanoparticles have the potential to serve as high-performance fertilizers, benefiting both rice yield and quality.