|
in
| Title : |
Evaluation of rice genotypes for resistance to sheath blight under field contions |
| Material Type: |
printed text |
| Authors: |
Bedanand Chaudhary ; Nabin Kumar Dangal, Author ; Parbati Joshi, Author ; Sudeep Kumar Upadhyay, Author |
| Pagination: |
303-312 p. |
| Languages : |
English (eng) |
| Keywords: |
Genotypes ; resistance field conditions sheath blight |
| Abstract: |
Sheath blight of rice, caused by Rhizoctonia sol ani, is one of the most important rice diseases
worldwide; however, no rice cultivar has been found to be completely resistant to this fungus .
Resistance of rice to sheath blight is quantitative, and involves two mechanisms:
physiological resistance and disease escape. Disease escape is mainly governed by plant
structure or plant morphology and physiologically resistance genotypes may exhibit disease in
the field conditions. Therefore, field screening experiments were conducted to address
morphological resistance (disease escape) in rice to sheath blight during the 2011 and 2012
wet season at Regional Agricultural Research Station, Tarahara. A total of28 in 2011 and 174
rice genotypes in 2012 were tested for morphological resistance. The susceptible hill (Swama)
of 56 day old plants was inoculated with infected pieces of rice stem. Number of infected
tillers of test entries was recorded on 14 days after inoculation and continued for three
scorings in both years at 7 day-intervals. During 20 11 disease incidence and area under
disease progress curve (AUDPC) varied significantly among the tested rice genotypes. The
varieties Tetep and lAC 165 had the lowest and highest terminal disease incidence and
AUDPC, respectively. Sabitri, MTU 1010 and IR 26 also recorded lower AUDPC values.
During 2012, rice genotypes varied for disease incidence from 0.0 to 50%. Disease incidence
progressed fast in some entries especially in quality rice. In the first scoring, 24 entries were
disease free (DF) and 32 were moderately resistant (MR). Out of 174 entries, 109, 8 and l
lines were moderately susceptible (MS), Susceptible (S) and highly susceptible (HS),
respectively. In the second scoring, 48, 26, 86 and 14 lines were DF, MR, MS and S,
respectively, to the disease. In the final scoring, IR 79913 -B-1 76-B-4, NR 1887-8-1-1-2,
IR79907-B-425-B-3 , IR 83381-B-B-7-1 and IR 87751 -20-4-4-2 were disease free. Out of
174, 29 genotypes were MR; similarly, 128, 11 and I were MS, S and HS to the disease,
respectively. Based on AUDPC values, 5 genotypes were grouped as DF, 67 as MR, 92 as MS
and 10 as S, respectively. More number of entries scored disease free in the second scoring
than that in the ftrst one. This was because separate hills were considered for scoring in the
different dates. Thus, the result showed that the disease incidence in rice genotypes differed
depending on microclimate conditions of the plants |
| Link for e-copy: |
http://elibrary.narc.gov.np/?r=916 |
in
Evaluation of rice genotypes for resistance to sheath blight under field contions [printed text] / Bedanand Chaudhary ; Nabin Kumar Dangal, Author ; Parbati Joshi, Author ; Sudeep Kumar Upadhyay, Author . - [s.d.] . - 303-312 p. Languages : English ( eng) | Keywords: |
Genotypes ; resistance field conditions sheath blight |
| Abstract: |
Sheath blight of rice, caused by Rhizoctonia sol ani, is one of the most important rice diseases
worldwide; however, no rice cultivar has been found to be completely resistant to this fungus .
Resistance of rice to sheath blight is quantitative, and involves two mechanisms:
physiological resistance and disease escape. Disease escape is mainly governed by plant
structure or plant morphology and physiologically resistance genotypes may exhibit disease in
the field conditions. Therefore, field screening experiments were conducted to address
morphological resistance (disease escape) in rice to sheath blight during the 2011 and 2012
wet season at Regional Agricultural Research Station, Tarahara. A total of28 in 2011 and 174
rice genotypes in 2012 were tested for morphological resistance. The susceptible hill (Swama)
of 56 day old plants was inoculated with infected pieces of rice stem. Number of infected
tillers of test entries was recorded on 14 days after inoculation and continued for three
scorings in both years at 7 day-intervals. During 20 11 disease incidence and area under
disease progress curve (AUDPC) varied significantly among the tested rice genotypes. The
varieties Tetep and lAC 165 had the lowest and highest terminal disease incidence and
AUDPC, respectively. Sabitri, MTU 1010 and IR 26 also recorded lower AUDPC values.
During 2012, rice genotypes varied for disease incidence from 0.0 to 50%. Disease incidence
progressed fast in some entries especially in quality rice. In the first scoring, 24 entries were
disease free (DF) and 32 were moderately resistant (MR). Out of 174 entries, 109, 8 and l
lines were moderately susceptible (MS), Susceptible (S) and highly susceptible (HS),
respectively. In the second scoring, 48, 26, 86 and 14 lines were DF, MR, MS and S,
respectively, to the disease. In the final scoring, IR 79913 -B-1 76-B-4, NR 1887-8-1-1-2,
IR79907-B-425-B-3 , IR 83381-B-B-7-1 and IR 87751 -20-4-4-2 were disease free. Out of
174, 29 genotypes were MR; similarly, 128, 11 and I were MS, S and HS to the disease,
respectively. Based on AUDPC values, 5 genotypes were grouped as DF, 67 as MR, 92 as MS
and 10 as S, respectively. More number of entries scored disease free in the second scoring
than that in the ftrst one. This was because separate hills were considered for scoring in the
different dates. Thus, the result showed that the disease incidence in rice genotypes differed
depending on microclimate conditions of the plants |
| Link for e-copy: |
http://elibrary.narc.gov.np/?r=916 |
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