Concurrent effect of phosphorus, nanoparticles and phosphorus solubilizing bacteria influences root morphology, soil enzymes and nutrients uptake in upland rice (Oryza sativa L.)

Abstract

Phosphorus and zinc are important nutrient elements of concern in upland rice production. To determine the suitable combination of phosphorus, nanoparticles (NPs), and bio-fertilizer application as an alternative nutrient management approach in upland rice cultivation, a Polyvinyl Chloride (PVC) column experiment was conducted under controlled conditions in 2015. The treatments consisted of three phosphorus levels, two foliar sprays of NPs (ZnO and TiO₂), and PSB seed treatment. The results indicated that the combined application of P (50 kg ha⁻¹), ZnO NPs (500 ppm), and PSB seed treatment (20 g kg⁻¹) improved the root system architecture traits of rice (total root length: 3.73–6.74%, diameter: 8.57–22.22%, and volume: 3.40–3.70%) at depths of 0–30 cm and 30–60 cm, compared to higher P + TiO₂ NPs + no PSB. Consequently, this combination led to an enhancement in photosynthetic leaf area (by 3.3%), tiller numbers (by 7%), and dry matter production (by 35.5%). The favorable root growth resulting from the application of higher P and PSB enhanced zinc uptake by rice grains (by 38.44%) and straw (by 26.99%). Furthermore, the supplemental application of PSB improved the activity of soil enzymes such as dehydrogenase and phosphatase. As a result, maximum phosphorus use efficiency (PUE; 31.5%) was achieved through the combined application of P (50 kg ha⁻¹) × ZnO NPs × PSB. In conclusion, this study demonstrated the beneficial effects of an integrated approach involving phosphorus, PSB, and metal oxides (ZnO NPs) as a fertilizer management strategy to enhance the total biomass and PUE of upland rice.

Keywords:

• Nanoparticles
• phosphorus
• root system
• soil enzymes
• upland rice

Acknowledgments

The authors express their gratitude to Dr C.D. Lokhande, Emeritus Professor of Department of Physics, Shivaji University, Kolhapur, India for their help in interpretation in nano sciences. This research was supported by the University of Agricultural Sciences, Dharwad, Karnataka to conduct field experiments and laboratory analysis.

Authors’ contributions

A.M.J., B.N.A., M.P.P., K.K.M., and H.M.H. planned, designed and conducted the field experiments, lab analysis and writing of manuscript; G.S and R.N. performed statistical analysis of the data, manuscript writing, editing and preparation of graphs.

Disclosure statement

There are no conflicts of interest between authors.

Data availability statement

All data are available in the manuscript.

Additional information

Funding

This research was funded by the University of Agricultural Sciences, Dharwad for experimentation and laboratory analysis. The authors are grateful to the Department of Agronomy and Bio-chemistry, University of Agricultural Sciences, Dharwad, India for facilitating needful requirements to conduct the experiment.