Studies on bacterial parasite, pasteuria penetrans (Ex thorne) sayre & starr on root-knot nematode, meloidogyne javanica (Treub) chitwood
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Date
2012
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Publisher
CCSHAU
Abstract
Influence of root exudates (REs) and cell free plant root extracts (CFPREs) of brinjal, cowpea,
cluster bean, garden bean, okra and tomato was tested on the germination of Pasteuria penetrans
endospores. REs and CFPRE of all the plant species did not induce the germination of P. penetrans
endospore. In garden bean CFPRE, cauliflower-like colonies similar to P. penetrans were observed in
endospore suspension treated with alcohol. In all the treatments rod-shaped lumps of bacteria were
evident; they may be contaminants because intact endospores of P. penetrans were also present. Based
on a laboratory bioassay, a statistical model was developed for the estimation of P. penetrans
endospores in field soils. The regression equation y= 0.045x + 3.779 with R2 = 0.89 was calculated for
M. javanica. In a green-house experiment, the role of P. penetrans in the suppression of M. javanica
was estimated in naturally infested field soil. Field soil was steam sterilised or treated with
formalin/fungicides. Formalin and Bavistin proved to be phytotoxic. P. penetrans alone infected 87.5%
nematode females and reduced egg production by ca. ten times. Native fungal and bacteria promoted
attachment of P. penetrans endospores but inhibited parasitisation of nematode females by P.
penetrans in untreated soil. The development of P. penetrans under open-field and poly-house
(ordinary and hi-tech) conditions was studied in winter season. Poly-houses (both ordinary and hi-tech)
enabled raising the maximum temperature by 10-12 °C during day time, but there were negligible
differences in the minimum temperatures. M. javanica completed it life cycle (females with egg sacs)
in 60 days in hi-tech, 70 days in ordinary poly-house and 80 days in open-field conditions. P. penetrans
development could not keep pace with that of nematode and it stopped at thallus stage. No mature
endospores were found. P. penetrans failed to curtail the reproduction of M. javanica even in hi-tech
poly-house, although infection did take place.
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Keywords
Fractionation, Proteins, Carbohydrates, Legumes, Biological phenomena, Productivity, Grasses, Nitrogen, Wheats, Crop residues