Enhancing crop productivity through Phosphorus Solubilizing Bacteria: Impacts on Phosphorus uptake in Groundnut (Arachis hypogaea L.)

Abstract

Phosphorus fertilizers in soil rapidly form insoluble complexes with metals like Fe, Al, Ca, and Mg, resulting in low phosphorus use efficiency (20-25%) in crops such as groundnut (Arachis hypogaea L.), a major oilseed in India. Phosphate-solubilizing bacteria (PSB) including Azotobacter, Bacillus, Pseudomonas, and their consortium enhance P availability through organic acid production and phosphatase activity, improving plant uptake and yield. This study evaluated seed treatments with PSB at recommended (50 kg ha⁻¹ single superphosphate equivalent) and double P doses in field trials (2019-2021, Punjab Agricultural University, Ludhiana) using groundnut variety SG99 in a randomized block design. Physiological (SPAD, pigments, RWC, membrane stability) and biochemical (leghaemoglobin, nitrite/nitrate reductase, sugars, proteins) parameters were assessed at 70 days after sowing. PSB inoculants significantly boosted chlorophyll a (up to 1.91 mg g⁻¹ FW with Azotobacter double dose), total chlorophyll (2.36 mg g⁻¹ FW), carotenoids (0.486 mg g⁻¹ FW), leghaemoglobin (3.56 mg g⁻¹ nodule FW with Bacillus double dose), enzyme activities (nitrite reductase 0.982 µmol NO₂⁻ h⁻¹ g⁻¹ FW; nitrate reductase 0.369 µmol NO₂⁻ h⁻¹ g⁻¹ FW), RWC (70.70%), and membrane stability (76.93%) compared to P-only controls. Total sugars reached 15.59 mg g⁻¹ DW with Bacillus double dose. These improvements align with recent findings on PSB enhancing groundnut yield by 7-13% via better P uptake.