Application of green synthesized bimetallic nZVI-Cu nanoparticle as a sustainable alternative to chemical fertilizers to enhance growth and photosynthetic efficiency of rice seedlings

Application of nanomaterials in agriculture has been extensively explored over the past decade leading to a wide ambit of nanoparticle-based agrochemicals. Metallic nanoparticles consisting of plant macro-and micro nutrients have been used as nutritional supplements for plants through soil amendments, foliar sprays, or seed treatment. However, most of these studies emphasize monometallic nanoparticles which limit the range of usage and effectivity of such nanoparticles (NPs). Hence, we have employed a bimetallic nanoparticle (BNP) consisting of two different micro-nutrients (Cu & Fe) in rice plants to test its efficacy in terms of growth and photosynthesis. Several experiments were designed to assess growth (root-shoot length, relative water content) and photosynthetic parameters (pigment content, relative expression of rbcS, rbcL & ChlGetc.). To determine whether the treatment induced any oxidative stress or structural anomalies within the plant cells, histochemical staining, anti-oxidant enzyme activities, FTIR, and SEM micrographs were undertaken. Results indicated that foliar application of 5 mg L-1 BNP increased vigor and photosynthetic efficiency whereas 10 mg L-1 concentration induced oxidative stress to some extent. Furthermore, the BNP treatment did not perturb the structural integrity of the exposed plant parts and also did not induce any cytotoxicity. Application of BNPs in agriculture has not been explored extensively to date and this study is one of the first reports that not only documents the effectivity of Cu-Fe BNP but also critically explores the safety of its usage on rice plants making it a useful lead to design new BNPs and explore their efficacy.

Automated summary

The application of nanomaterials in agriculture has seen extensive exploration in the past decade, resulting in a wide range of nanoparticle-based agrochemicals. Metallic nanoparticles composed of plant macro- and micronutrients have been used as nutritional supplements for plants through various methods. However, most studies have focused on monometallic nanoparticles, limiting their usage and effectiveness. In this study, a bimetallic nanoparticle consisting of copper and iron was used in rice plants to test its efficacy in terms of growth and photosynthesis. Experiment results showed that foliar application of 5 mg L-1 bimetallic nanoparticle increased vigor and photosynthetic efficiency, while a concentration of 10 mg L-1 induced oxidative stress to some extent. Furthermore, the bimetallic nanoparticle treatment did not cause structural anomalies or cytotoxicity in the exposed plant parts. This study not only demonstrates the effectiveness of Cu-Fe bimetallic nanoparticles but also critically explores their safety on rice plants, providing valuable insights for designing new bimetallic nanoparticles and exploring their efficacy.