Influence of phosphate and potassium solubilizing bacteria on performance of crop, endophytic and rhizosphere microbial population in chamomile

Phosphate (Bacillus megaterium) and potassium (Frateuria aurantia) solubilizing bacteria (PSB and KSB) were assessed for their agronomic impact on chamomile performance in a pot experiment at CSIR-CIMAPRC, Bengaluru. Results demonstrated that 75% recommended dose of fertilizer (RDF) combined with PSB and KSB significantly improved chamomile performance, enhancing plant height (41.4 cm), stem diameter (1.10 mm), number of flowers (348.67), flower: leaf ratio (1.24), and flower dry weight (4.28 g plant-1) compared to control, RDF alone, and sole solubilizer application. The combined application with 100% RDF synergistically increased rhizosphere bacterial population from 25 × 104 Cfu g-1 to 57 × 104 cfu g-1, while 75% RDF + PSB + KSB resulted in 53 × 104 cfu g-1. Morphological and biochemical analyses revealed diverse variations in chamomile endophytes and rhizosphere soil bacterial populations, mainly Bacillus and Streptococcus genera. PSB and KSB, whether applied individually or combined, significantly influenced chamomile growth and yield, with microbial dynamics enhancing nutrient solubilization and availability.