Author(s):

M Lakshmi Naga Nandini, SK Nayab Rasool, CH Ruth and K Gopal

Abstract: Rhizome rot caused by Pythium aphanidematum is one of the major constraints for the cultivation of turmeric in Andhra Pradesh and cent per cent crop loss has been estimated in susceptible varieties. Biocontrol using endophytic microorganisms is one of alternative control methods to support agriculture sustainability. The objective of these experiments are to isolate endophytes from rhizomes of healthy turmeric plants from 16 locations of Andhra Pradesh and to estimate their biocontrol potential against the rhizome rot pathogen. Among 154 endophytic isolates obtained, 12 out of 79 bacteria, 16 out of 68 fungi, and four out of seven actinomycetes were antagonistic to Pythium aphanidematum in vitro. Several bacterial isolates belonging to four bacterial genera viz., Bacillus, Pseudomonas, Klebsiella and Citrobacter were obtained and identified using standard biochemical methods. Of the bacterial endophytes isolated in the study, only 50% of the isolates showed antagonistic activity against Pythium aphanidermatum, the pathogen causing rhizome rot disease in turmeric. Bacterial metabolites like siderophore, hydrogen cyanide, indole acetic acid and salicylic acid in the culture media were studied. The result showed that comparatively the maximum quantity of siderophore (53.6%), hydrogen cyanide (45%), and salicylic acid (48.7%) was produced by Pseudomonas and indole acetic acid (48.2%) by Bacillus. Among the isolated endophytes, Pseudomonas was found to exhibit superior antagonistic activity against the test pathogen.

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