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STUDIES ON BIOLOGICAL CONTROL OF RICE SHEATH BLIGHT CAUSED BY Rhizoctonia solani Kuhn USING Trichoderma sp

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Title STUDIES ON BIOLOGICAL CONTROL OF RICE SHEATH BLIGHT CAUSED BY Rhizoctonia solani Kuhn USING Trichoderma sp
 
Creator SOUJANYA LAKSHMI, R
 
Contributor ANIL KUMAR, P
 
Subject fungi, biological development, diseases, rhizoctonia solani, rice, planting, biological control, application methods, pathogens, biochemical compounds
RICE, Rhizoctonia solani, Trichoderma sp
 
Description The present investigation was undertaken to screen five isolate of
Trichoderma spp. belonging to three isolates of T. harzianum (Th 4, Th7 and Th8), one
isolate each of T. virens (Tv11) and T. aureoviride (Ta) against Rhizoctonia solani, the
rice sheath blight pathogen and to find feasibility of utilizing the most potential isolate
to manage the sheath blight in vivo.
Based on the quantitative and qualitative parameters, the T. harzianum (Th4)
with superior radial growth in monoculture and faster occupation of R. solani colony
and lysis of R. solani was found better in comparison with other four test isolates and
hence choosen for further studies on its antagonistic potential in vitro and in vivo.
Microscopic observations on mycoparasitism of T. harzianum (Th4) on
R. solani were observed at the interaction zone using compound and scanning electron
microscopes which revealed coiling, parallel growth and appressoria formation by Th4
hyphae around the R. solani hyphae. Penetration of R. solani hyphae by Th4 resulted
in the pores on R. solani cell wall (indicating penetration sites), coagulation and lysis
of R. solani hyphae.
The production of chitinases, cellulases and proteases by T. harzianum (Th4)
was observed when R. solani was used as sole nutrient source. However, 87.5 %
reduction in dry wt of Th4 compared to dry wt on Czapek Dox broth suggested that
Th4 cannot totally depend on R. solani hyphae for its survival.
A temperature of 300 C and pH 6.0 favoured the Trichoderma, where there
was an increase in the antagonistic potential of Th4 and decrease in the radial growth
of R. solani. The better growth of R. solani at 200C indicated the better chances of
survival of R. solani at that respective temperature.
There was no effect of inhibitory volatiles of T. harzianum (Th 4) on the growth
reduction of R. solani at all the temperatures and pH levels tested.
Influence on the dry wt of R. solani due to Th 4 culture filtrate obtained from
three different incubation temperatures was not observed. However, there was
maximum reduction in the radial growth of R. solani at maximum concentration
(50%) of culture filtrate of T. harzianum (Th4) obtained from three different pH
levels.
Seed treatment or seedling dip with Th4 spore suspension @ 108 spores/ml and
10 spores/ml resulted in least lesion area at six days after pathogen inoculation
compared to pathogen inoculated check. This indicated that the Trichoderma could
induce systemic resistance in rice plants.
12
Hexaconazole (0.2%) spray was found to be effective resulting in least lesion
area compared to foliar spray of Th4 spore suspension @ 108 spores/ml and 1012
spores/ml which were significantly lower than pathogen inoculated check at six days
after pathogen inoculation.
No drying of inoculated leaf in case of hexaconazole and a two days delay in
leaf drying in case of Trichoderma treatments compared to pathogen inoculated check
revealed that Trichoderma could only give an initial protection from rice sheath blight
pathogen, R. solani. Further, Trichoderma was not phytotoxic to rice plants.
 
Date 2016-06-03T14:22:05Z
2016-06-03T14:22:05Z
2011
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/66723
 
Language en
 
Relation D9029;
 
Format application/pdf
 
Publisher ACHARYA N. G. RANGA AGRICULTURAL UNIVERSITY