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STUDIES ON DETECTION AND SEED TRANSMISSION OF Botrytis GREY MOLD IN CASTOR (Ricinus communis L.)

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Title STUDIES ON DETECTION AND SEED TRANSMISSION OF Botrytis GREY MOLD IN CASTOR (Ricinus communis L.)
 
Creator SIVA KUMAR THE GREAT, V
 
Contributor MEENA KUMARI, K. V. S
 
Subject sowing, fungi, biological phenomena, diseases, castor (genus), application methods, germinability, developmental stages, pathogens, planting
Ricinus communis L.
 
Description Grey mold disease of castor caused by Botrytis ricini Godfrey. is potentially a very
destructive disease, and became a serious problem now-a-days wherever the crop is grown.
Study on etiology and symptomatology of the disease, seedborne nature, effect of B. ricini
on seed quality parameters, effect of seed health testing methods on the growth of the
pathogen, location of B. ricini infection in castor seed, seed to seedling transmission
studies, bioassay of fungicides and bioagents was carried out during the present
investigation.
The pathogen induced typical grey mold symptoms both under field and artificially
inoculated conditions. The characteristic symptoms include grey cob webby wooly growth
on flowers and capsules leading to rottening and softening; hollow mature seed with
discoloured seed coat and loss in seed weight; irregular light brown lesions with distinct
margins often covered by grayish mouldy growth of the pathogen on the leaves; and
hanging down and breaking of tender branches and spikes.
The pathogen was isolated from infected host plant capsules, purified and identified
as Botrytis ricini Godfrey based on cultural and morphological characters and the
pathogenecity was proved using castor cv. DCS-9.
In moist blotter incubation, 13 fungi viz., Aspergillus flavus, Fusarium
verticilloides, Rhizopus spp., Verticillium spp., Alternaria alternata, Aspergillus niger,
Phoma spp., Acremonium apii, Trichothecium roseum Cladosporium spp, Curvularia
lunata were found associated with seeds of the castor cv. DCS-9. In naturally infected
seeds, the incidence of Fusarium semitectum was the highest (37.5 and 35 per cent in
unsterilized and surface sterilized seeds respectively). In artificially inoculatd seeds, the
incidence of Botrytis ricini was highest (22.5 and 17.5 per cent in unsterilized and sterilized
seeds respectively). The association of B. ricini in naturally infected and artificially
inoculated (sterilized and unsterilized) seeds was observed, indicating that the pathogen is
seedborne in nature. Mean seed quality parameters viz., germination, oil content and
seedling vigour index were significantly higher in healthy seeds than B. ricini infected
seeds, whereas moisture content was high in B. ricini infected seeds than healthy seeds of
castor cv. DCS-9.
Among the five seed health methods tested, maximum growth and sporulation of B.
ricini was observed on V8 juice agar method followed by castor leaf extract method,
whereas, very less growth of B. ricini was observed in deep freeze method.
Among the different parts of castor seed B. ricini incidence was maximum in
caruncle and seed coat in both naturally infected and artificially inoculated seeds. Whereas,
B. ricini incidence was totally absent in embryo in both naturally infected and artificially
inoculated seeds.
Transmission of the fungus from seed to seedling (5 per cent in paper towel method
and 2.5 per cent in soil method) was observed in artificially inoculated unsterilized seeds.
Maximum seed rotting was observed in paper towel than sand and soil methods. In paper
towel seed rotting was maximum (80 per cent) in naturally infected unsterilized seeds and
germination percentage was higher (85.0 per cent) in artificially inoculated sterilized seeds.
Seedling mortality and seedling infection were very low when compared to seed rotting. In
soil seedling infection was very low (2.5 per cent) whereas in sand, seedling infection was
totally absent.
Among all the fungicides and biocontrol agents tested against B. ricini, carbendazim
(0.2%) and T. viride (0.4%) were found to be most effective in reducing B. ricini incidence
whereas hexaconazole and Bacillus spp. were found to be least effective in reducing B.
ricini incidence.
Incidence of B. ricini was minimum in seeds treated with carbendazim (0.2%)
followed by carbendazim + mancozeb (0.25%) and T.viride (0.4%) in blotter method. In
paper towel method seeds treated with carbendazim (0.2%) showed maximum germination,
shoot, root lengths, shoot, root dry weights and seedling vigour index followed by T. viride
(0.4%) and carbendazim + mancozeb (0.25%). In sand method, maximum germination,
shoot, root lengths, shoot, root dry weights and seedling vigour index was recorded in seeds
treated with T. viride (0.4%) followed by carbendazim (0.2%).
The disease incidence was found to be lowest when sprayed with carbendazim
(0.2%) followed by carbendazim + mancozeb (0.25%) and the reduction in disease over
control was maximum with carbendazim (0.2%) followed by carbendazim + mancozeb
(0.25%) and T. harzianum (0.4%) on the detached racemes of castor cv. DCS-9 under
controlled conditions.
 
Date 2016-06-09T13:54:18Z
2016-06-09T13:54:18Z
2011
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/67113
 
Language en
 
Relation D8882;
 
Format application/pdf
 
Publisher ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY