Evaluation of potassium solubilizing bacteria in tea fields for increased productivity and soil health

Abstract

The present research proposal was designed to evaluate the efficacy of indigenous potassium solubilizing bacteria (KSB) on the plant growth promotion of tea plants, potassium solubilizing ability, soil health maintenance and the quality attributes of black tea. The native KSB strains were isolated from southern Indian tea plantation soils collected from various agroclimatic zones, screened based on their potassium (K) solubilization efficiency and subsequently evaluated under field condition. In this study, six efficient strains among 152 isolates were selected based on their solubilization efficiency of various sources of potassium in Aleksandrov medium containing muriate of potash (MOP), sulphate of potash (SOP) and Montmorillonite. The results showed that K solubilizing efficiency of bacterial isolates on Aleksandrov medium was ranged between 0.30 and 1.41 cm. The population density of KSB strains were found to be high in the rhizosphere soils collected from China hybrids viz., UPASI-9 (18.5x x104/gm soil dry weight) and comparatively lesser with Assam hybrids viz., BSS-1 seedling plants. Distribution of population density in the rhizosphere region revealed that it was decreased when the distances as well as depth of soil sampling from the plant were increased. The southwest monsoon had profound influenced upon the population density of KSB at tea planting districts of Valparai, Munnar, Coonoor and Gudalur areas whereas Vandiperiyar and Koppa exhibited very less and benefited during northeast monsoon. K solubilization of the strain VKSB12 was ranged between 28.26 mg/l and 41.63 mg/l and MOP source was found to be preferred by KSB strains over SOP and montmorillonite sources. The order of K solubilization iv by KSB strains was in concordance with the usage of K source in tea plantations. Efforts were made to identify the selected six KSB strains by studying of their morphological, biochemical, physiological and molecular traits.