Native tea rhizospheric Streptomyces costaricanus WZ162 against Ustulina zonata causing Charcoal stump rot disease in Tea ( Camellia sinensis)

Abstract

The rhizosphere microbiology of plantation crops is less explored for the antagonistic actinomycetes, which
are agriculturally important soil microbial communities. This study deals with the population dynamics
of actinomycetes present in the rhizosphere of tea bushes in three different zones of the Brahmaputra
valley. A total of 17 actinomycetes strains were isolated from rehabilitated, non-rehabilitated and virgin
soils of selected tea gardens, out of which eleven Actinomycetes strain showed antagonistic potentiality
when screened for its antagonism against Ustulina zonata, a relevant fungal pathogen responsible for
causing charcoal root rot of tea. Among the eleven potential actinomycetes strains two of the strains MM/
PH/AC-02 and MM/PH/AC-09 identified as Streptomyces spp. showed more than 45 percent inhibition
under study in in vitro condition. Among the two, MM/PH/ AC-09, identified as Streptomyces costaricanus,
was found to control the tea pathogen as well as promote the growth of tea bushes under nursery trials.
The results of this study facilitate the exploitation of this potentially antagonistic Streptomyces sp from
the rhizosphere of tea and other plantation crops with diverse disease control efficiency.
Keywords: Antagonistic, Rehabilitation, Non-Rehabilitation, Virgin, Streptomyces costaricanus Ustulina zonata.