Colonization of rhizosphere of tea by growth promoting bacteria

Abstract

Based on a detailed study conducted to isolate microbes from soil samples collected from various tea gardens located in the Indian Himalayan region, two bacteria namely Bacillus subtilis and Pseudomonas corrugata have been selected as promising inoculants for field application in tea gardens. Bioassays based on the inoculation of seed raised and tissue culture raised tea plants had earlier indicated the biocontrol and growth promotion properties of selected bacteria.

With a view to introduce these bacterial isolates eventually in the tea gardens, suspension cultures were raised and applied (inoculated) in the rhizosphere region of both seedling and cutting raised (four clones) young tea plants under net-house conditions. Monthly enumeration of bacterial (including free living nitrogen fixers), fungal and actinomycetes populations, up to a period of one year, indicated excellent rhizosphere colonization by the inoculated bacteria. The presence of "introduced" bacteria in the rhizosphere was confirmed by the use of antibiotic markers. The inoculated tea plants have been transferred to new plantation sites, near Kausani in District Bageshwar, Uttaranchal for further monitoring of growth and overall performance.