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INVESTIGATION ON RICE GRAIN DISCOLOURATION COMPLEX

KrishiKosh

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Title INVESTIGATION ON RICE GRAIN DISCOLOURATION COMPLEX
 
Contributor GAJRE, NIRAV K.
 
Subject sowing, rice, grain, fungi, diseases, biological phenomena, application methods, pathogens, developmental stages, germinability
 
Description Rice (Oryza sativa L.) is the staple food of more than 60 per cent
population of the world. Many hybrids and improved high yielding varieties have
been developed in several countries in recent years, but they are susceptible to
diseases due to narrow genetic makeup. Therefore, discarded by the farmers within a
short period.
Considering the devastating nature of the Grain discolouration disease
and huge quantity as well as quality losses, the present investigation was carried out
on various aspects to generate scientific information on rice grain discolouration and
to develop suitable management strategies under South Gujarat condition to save crop
losses.
The natural symptoms and signs of diseased discoloured rice seed and
pathogen associated with grain discolouration were studied by collecting discoloured
seeds and associated diseased samples from South Gujarat region. The microscopic
examination, isolation and identification of detected fungi were, Sarocladium oryzae,
Fusarium moniliforme, Curvularia lunata, Alternaria alternata, and Aspergillus niger
belonging to five genera. The pathogenicity test of main pathogens viz; S. oryzae, F.
moniliforme and C. lunata was proved to be positive. The isolated fungus satisfied
Koch’s postulate on rice plant.
The single grain insertion technique with S. oryzae was most efficient
and rapid technique for producing grain discolouration symptoms along with sheath
rot symptoms and signs.
The maximum loss (41.36 %) in seed weight was recorded in cv. Gurjari
(category D) followed by cv. Jaya (41.25).
The seed inoculated with various pathogens reduced the germination.
The germination per cent of inoculated seed with S. oryzae was 52.22 in Jaya and
54.98 in Gurjari, in case of F. moniliforme, it was 64.24 per cent Gurjari and 65.96
per cent in Jaya. The per cent germination in seed inoculated with A. alternata was
74.74 and 76.48 per cent in Jaya and Gurjari, respectively. While, in case of seed
inoculated with A. niger, germination was 77.16 per cent in cv.Jaya and 78.40 per cent
in cv.Gurjari.
Out of 18 entries screened against rice GD disease, Masuri was found
resistant while rest were found susceptible.
In dual culture technique, pathogen at periphery and pathogen at centre
showed strong antagonistic effect of Pseudomonas fluorescens, Trichoderma viride
and Bacillus subtilis against S. oryzae in vitro test.
The phytoextracts were screened in vitro by poisoned food technique
against S. oryzae. The extracts of neem (Azadirachta indica Juss.) and gando baval
(Prosopis juliflora L.) were proved superior in inhibiting mycelial growth, followed
turmeric (Curcuma longa L).
Among eleven fungicides tested in vitro by poisoned food technique
against S. oryzae, propiconazole (Tilt 25% EC) and carbendazim + mancozeb (Sixer
75% WP) at all three concentrations were found highly effective and hexaconazol
(Contaf 5% EC) at 1000 ppm and 1500 ppm, difenconazole (Score 25% EC),
carbendazim (Bavistin 50% WP) were moderately effective.
All fungicides tested, increased seed germination, shoot and root length
significantly as compared to control. The S. oryzae inoculated seed treated with
Thiram 75% WP, Sixer 25% EC and Captan 75% gave significantly more seed
germination, shoot and root length of seedling than the control.
The management of rice grain discolouration (cv. Jaya) revealed that
carbendazim + mancozeb was significantly superior over rest of the fungicides for all
the attributes viz., discoloured grain, unfilled grain, grain yield, straw yield and 1000
grain wt. at both the location as well as in pooled analysis. The next effective
treatment was propiconazole which was at par with P. fluorescens.
Association of sheath mite with S. spinki grain discolouration was found
positive. Highest per cent discoloured grain and sheath rot was found in combine
treatment of mite and pathogen, whereas pathogen S. oryzae and mite S. spinki alone
treatments produced less severity of disease.
 
Date 2016-04-28T12:56:27Z
2016-04-28T12:56:27Z
2012-01
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/65632
 
Language en
 
Format application/pdf
 
Publisher Navsari Agricultural University, Navsari