Abstract
Rice blast caused by Magnaporthe grisea is an economically important disease which distributed in most rice growing areas of the world. Yield losses up to 100% are attributed to the blast disease in different rice growing regions of Uganda. In order to combat this disease screening of forty-six introduced Korean rice accessions and two checks IR-64 (resistant) and NERICA-1 (susceptible) were done in a 6 by 8 alpha lattice design in two replications under natural infestation in field conditions, and three replications in the screen house at National Crops Resources Research Institute (NaCRRI) of Uganda in 2015, A and B seasons. Final leaf blast severity, lesion size, area under disease progress curve (AUDPC) values, panicle blast and grain yield were highly significant among genotypes. Genotypes SRHB-133, SRHB-93 and SRHB-78 were resistant to rice blast in both field and screenhouse conditions and showed a lower lesion size. Therefore, these genotypes that consistently showed resistance to rice blast disease can be used as a source of resistance gene for rice blast. This leads to conclude that screening in both the field across seasons and confirming their resistance in the screen house helps the breeder to identify the genotypes that are truly resistant for further utilization as resistant sources. Key words: Rice blast, screening, Magnaporthe grisea, Uganda.
Highlights
Rice (Oryza sativa L.) is one of the most important stable foods for more than half of world’s population
Their results revealed that while none of the varieties were immune to blast, genotypes were grouped as resistant, moderately resistant and susceptible. These variations may be attributed variously to genetic difference for resistance to blast, or to variation in environment from season to season and screening conditions. These findings indicate that screening under both field and screen house conditions and in several seasons could be effective for getting genotypes with resistant genes for rice blast disease
This study showed the value of testing the reaction of the introduced Korean rice genotypes to the Ugandan situation, even when they were introduced by the source as being resistant
Summary
Rice (Oryza sativa L.) is one of the most important stable foods for more than half of world’s population. It provides up to 50% of the dietary caloric supply and a substantial part of the protein intake in Asia (Muthayya et al, 2014). In Sub-Saharan Africa rice consumption among urban dwellers has steadily been grown. From 2002 to 2007, rice production in Africa had increased by an average of 3.2% per year, and from 2007 to 2012 by 8.4% per year (CGIAR, 2013). In Uganda rice production from year 2010 to 2014 increased from 93 to 95 thousand hectares, with a yield increment of 214 to 237 thousand tonnes (FAO, 2014). The production and productivity of the crop is hampered by a number of biotic and abiotic factors
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