Phosphorus uptake and growth promotion of chickpea by co-inoculation of mineral phosphate solubilising bacteria and a mixed rhizobial culture

Abstract

Isolation of phosphate solubilising bacterial strains was carried out from rhizosphere, roots and nodules of chickpea, to study the viability for solubilisation of tri-calcium phosphate and the effect on growth of chickpea plants. The potential of isolated bacterial strains to solubilise phosphate was qualitatively evaluated by the measurement of a clear zone around the colonies. The diameter of this zone ranged from 21 to 83 mm. Phosphate solubilisation, by phosphate solubilising bacterial isolates, was quantified by spectrophotometry and was found to range from 65 to 130.5 μg/mL. The drop in pH ranged from 5.6 to 3.6. The plant growth, shoot phosphorus and nitrogen concentrations, nodulation efficiency and nitrogenase activity were significantly enhanced, showing the positive effect of phosphate solubilising bacteria inoculation. Phosphate solubilising bacterial strains CPS-2, CPS-3 and Ca-18 had the maximum positive effect on shoot length, shoot dry weight and nodulation of chickpea plants. Treatments inoculated with non-phosphate solubilising bacterial strains IFA₁ and IFA₂ showed the minimum values in all the parameters.