Identification of biological variability of pyricularia oryzae and screening for variety resistance to rice blast disease in imbo plain region
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Date
2021
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Publisher
Sokoine university of agriculture
Abstract
In Burundi rice is a very important cereal crop used as a food of lux during the celebration
of important social events. Unlikely, rice productivity is greatly reduced by the attack of
rice blast disease caused by Pyricularia oryzae. Yield loss may go as high as 80% if
conducive conditions are present. However, rice farmers are still using contributing factors
to the disease development and fewer are known about the biological variability of blast
disease. The present study was conducted in the Imbo plain, a natural region of Burundi
with an overall objective to improve rice productivity by usage of rice blast disease
resistant varieties. Assessment of blast disease severity in farmer’s rice fields was carried
out using 0-9 scale and the use of contributing factors to the disease development was
carried out using a direct interview method. Biological variability of the pathogen was
done through the morphological and pathogenic characterization. Disease severity showed
significant difference in different Imbo plain locations (P=0.000). Variety resistance in
field conditions showed Gwizumwimbu and Kazosi as the highest susceptible varieties at
the frequency of 11.1% and 9% respectively. However, no significance difference was
observed (P>0.05). Morphological characterization led to 96 distinct isolates classified into
four groups based on colony colours: white (45), grey (38), black (10) and brown (3); two
groups based on the surface texture: cottony (69) and velvety (27) and two groups:
irregular (69) and regular (27) based on the colony margins. Pathogenicity test using 29
isolates showed that variety Watt, Mugwiza and Vuninzara can be cultivated as resistant
varieties (resistant at >60% to local isolates). Similarly, R-genes Piz-5 and Pi40 showed
high resistance to P. oryzae isolates across Imbo plain. In conclusion, rice blast disease is
distributed in all locations of Imbo plain region and isolates are diverse morphologically
and pathogenically.
Description
Keywords
Pyricularia oryzae, Rice blast disease, Variety resistance, Cereal crop, Natural region of Burundi