Rice yellow mottle virus (RYMV) is the most important rice - infecting virus in Africa. Isolates of the virus were collected from Eastern, Southern and Northern Provinces of Sierra Leone and evaluated for pathogenicity on rice, using visual symptom rating and other disease-related traits such as plant height and yield depression. Near Iso-lines NIL 2, NIL 16, NIL 54 and NIL 130, developed by AfricaRice and conferring RYMV resistance were evaluated for resistance to the disease under natural infection. The accessions, together with popularly grown released and local rice varieties, were evaluated by farmers in demonstration plots in the Eastern, Southern and Northern Provinces of Sierra Leone. Results show that the isolates varied in pathogenicity but all developed symptoms of the disease following inoculation of rice plants all the NIL accessions were resistant to the disease. NIL 2 was identified as the best variety by 5, 2.5 and 42.5% farmers in Kenema, Bo and Kambia, respectively. NIL 130 was also identified as the best variety by 7.5, 17.5 and 5% farmers in Kenema, Bo and Kambia, respectively. High tillering and panicles with many spikelets were the main selection criteria by farmers. NIL 16 and NIL 54 were location-specific and selected as the best variety by 20 and 12.5% farmers in Kenema and Kambia, respectively. The NILS, particularly NIL 2 and NIL 130 with multi-locational acceptance, show promise for rice varietal improvement in Sierra Leone.
Key words: Rice yellow mottle virus, isolates, pathogenicity, varietal selection.
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