Concentration and Method Dependent Effects of Nano-Nickel on Growth and Physiological Attributes of Cowpea
Sarbasree Goswami *
Department of Soil Science and Agricultural Chemistry, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh-221005, India.
Satish Kumar Singh
Department of Soil Science and Agricultural Chemistry, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh-221005, India.
Shubham Jaiswal
Department of Soil Science and Agricultural Chemistry, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh-221005, India.
Purushottam Dev
Department of Soil Science and Agricultural Chemistry, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh-221005, India.
Kajal Singh
Department of Soil Science and Agricultural Chemistry, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh-221005, India.
*Author to whom correspondence should be addressed.
Abstract
Aims: Nickel (Ni) is an essential micronutrient involved in important physiological and metabolic processes in plants, particularly urease activation and nitrogen metabolism. However, the beneficial effects of Ni are concentration-dependent, and excessive Ni may adversely affect plant growth and physiological performance. The use of nano-nickel (nano-Ni) offers an alternative approach for supplying Ni because of its enhanced reactivity and potential for efficient nutrient delivery. However, the response of cowpea to nano-Ni may vary according to both concentration and method of application. Therefore, the present study was undertaken to evaluate the effect of different concentrations of nano-Ni applied through soil, foliar spray and seed treatment on plant height, leaf area index (LAI) and SPAD value of cowpea.
Study Design: Completely Randomised Design (CRD) was undertaken.
Place and Duration of Study: Department of Soil Science and Agricultural Chemistry, Banaras Hindu University, Varanasi, Uttar Pradesh, from March 2023 to June 2023.
Methodology: A pot experiment was conducted using the recommended dose of fertilisers (RDF), along with different concentrations of nano-Ni applied through soil, foliar spray and seed treatment. For soil application, nano-Ni was applied at 0.10, 0.25, 0.50, 0.75, 1.0 and 1.5 mg kg⁻¹, whereas for foliar spray and seed treatment, nano-Ni was applied at 10, 25, 50, 75, 100 and 250 ppm. Plant height, LAI and SPAD value were recorded at 30 and 60 days after sowing (DAS). The experimental data were analysed statistically and treatment means were compared using Duncan's multiple range test (DMRT) at P ≤ 0.05.
Results: Nano-Ni application significantly affected plant height, leaf area index (LAI) and SPAD value of cowpea, with responses varying with concentration and application method. Under soil application, the maximum plant height was recorded at 0.75 mg kg⁻¹ at 30 DAS and 0.50 mg kg⁻¹ at 60 DAS, while LAI and SPAD were highest at 0.75 mg kg⁻¹ at both stages. Foliar application produced the highest plant height and LAI at 75 ppm at both stages, whereas the maximum SPAD value was recorded at 75 ppm at both 30 and 60 DAS. Under seed treatment, plant height and LAI were maximum at 25 ppm at both stages, while the SPAD value was highest at 75 and 50 ppm at 30 and 60 DAS, respectively.
Conclusion: Nano-Ni improved plant growth and physiological performance in cowpea at optimum concentrations. Foliar application at 75 ppm was most effective for plant height and LAI, whereas the optimum concentration for SPAD varied with the application method and growth stage. The decline at higher concentrations indicates a concentration-dependent response to nano-Ni.
Keywords: Growth attributes, physiological parameters, leaf area index, nickel, Nano-Ni, cowpea