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IDENTIFICATION OF EFFECTIVE ISOLATE OF PSEUDOMONAS FROM THE SOILS OF SOUTHERN TELANGANA ZONE AGAINST CASTOR WILT PATHOGEN

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Title IDENTIFICATION OF EFFECTIVE ISOLATE OF PSEUDOMONAS FROM THE SOILS OF SOUTHERN TELANGANA ZONE AGAINST CASTOR WILT PATHOGEN
 
Creator JAYAMMA, P.
 
Contributor SUBHASH REDDY
 
Subject PSEUDOMONAS, SOILS, SOUTHERN, TELANGANA, ZONE, CASTOR, WILT, PATHOGEN
 
Description Wilt of castor caused by Fusarium oxysporum f.sp. ricini which was earlier
considered as a disease of minor importance, now it became a major disease and an
impediment in the cultivation of the castor. Continuous use of agrochemicals in pest
and disease control leads to environment, soil and water pollution, where as
biological control of diseases is long lasting, less expensive, eco-friendly and
harmless to non target organisms. Keeping in view the benefits of biological control
of plant pathogens the present investigation is carried out.
Symptoms of the disease on seedlings showed characteristic yellowing and
bronzing of cotyledonary leaves associated with degenerated root system. Symptoms
on grownup plants manifested as stunting of the plant, yellowing of leaves,
production of black streaks on stems and discolouration of roots. The fungus
associated with the disease was isolated and identified as Fusarium oxysporum f.sp.
ricini and its pathogenicity was proved under greenhouse conditions.
Microorganisms are known to grow in the rhizosphere and provide frontline
defence for roots against the attack by plant pathogens. In the present study,
fluorescent Pseudomonads were isolated from the rhizosphere of crop plants like
sorghum, maize, groundnut, chilli, tomato, castor and also from various forest plants.
Twenty seven isolates were obtained from the 70 rhizosphere soil samples. Out of
which, eighteen isolates were identified as fluorescent Pseudomonads based on their
fluorescence nature under UV- light on Pseudomonas agar.
Isolated fluorescent Pseudomonads were screened against Fusarium
oxysporum f.sp. ricini under in vitro conditions using dual culture plate technique to
test the antagonistic potential. Three fluorescent Pseudomonas isolates (STPF-11,
STPF-14 and STPF-18) were found to be potential antagonists against the tested
fungal pathogen.
Under field conditions, agrochemicals like fungicides, insecticides and
herbicides etc. are used to control plant diseases and pests. In addition to
agrochemicals biocontrol agents are also used by farmers for controlling some
diseases. Because of this, the potential antagonistic PF (fluorescent Pseudomonads)
isolates were tested for their compatibility with the commonly used agrochemicals.
Among the different agrochemicals tested carbendazim, chlorpyriphos and
pendimethalin were found to be more compatible with PF isolates.
Disease management strategy was developed for wilt of castor under
greenhouse conditions. Among the treatments, treatment T3 (seed treatment with
STPF-14 isolate + soil application of Farm Yard Manure (FYM) incubated STPF -14
isolate) was highly effective with least per cent disease incidence of 26.56 per cent at
45 days after sowing. This treatment not only reduced the disease incidence to a
maximum extent, but also recorded maximum plant height (27.32 cm) root length
(6.36 cm) and maximum fresh (21.32 g) and maximum dry weight (5.19 g) of castor
when compared to other treatments.
 
Date 2016-07-28T13:27:49Z
2016-07-28T13:27:49Z
2009
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/70159
 
Language en
 
Relation D8506;
 
Format application/pdf
 
Publisher ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY RAJENDRANAGAR, HYDERABAD