Influence of Phosphorus Levels, Phosphorus-solubilizer and Phosphorus-mobilizers on Growth, Yield and Nutrient Uptake of FCV Tobacco

Abstract

Aims: The present study evaluates the effects of phosphorus (P) levels, the P-solubilizer Bacillus megaterium and the P-mobilizer Glomus mosseae on growth, yield, nutrient uptake and post-harvest soil properties of FCV tobacco. Study Design: Randomized Complete Block Design with seven treatments and three replications. Place and Duration of Study: Zonal Agricultural and Horticultural Research Station, Navile, Shivamogga, Karnataka, India, during Kharif 2017-18 and 2018-19, followed by on-farm validation across the Karnataka Light Soil region during 2020 and 2021. Methodology: Seven treatments combining 100% or 75% recommended phosphorus with the recommended nitrogen and potassium dose and either single or combined bioagent application were evaluated. Growth parameters, green leaf yield, cured leaf yield, top-grade equivalent, nutrient uptake and post-harvest soil properties were analysed using standard procedures. The best phosphorus-saving treatment was validated at 15 farmers’ fields. Results: Treatment T4, comprising 100% recommended NPK with both bioagents at 6.25 kg ha⁻¹ each, recorded higher plant height (12.6 cm), leaf area (617.2 cm² plant⁻¹), green leaf yield (10,795 kg ha⁻¹), cured leaf yield (1,060 kg ha⁻¹) and N, P and K uptake (36.98, 11.86 and 92.71 kg ha⁻¹, respectively) than recommended NPK alone. Treatment T7 showed comparable performance and, in on-farm validation, increased cured leaf yield by 6.6% over RDF. Conclusion: Combined use of Bacillus megaterium and Glomus mosseae with 75% recommended phosphorus may support reduced phosphorus application without compromising FCV tobacco productivity under Karnataka Light Soil conditions.