Abstract:

Rice (Oryza spp.) has long been an important food staple for many traditional rice growing communities. Key
developments in efforts to improve rice production such as the development of NERICA varieties have been
widely recognised. Nonetheless, emerging diseases such as the Rice Yellow Mottle Virus sobemovirus (RYMV)
undermine dissemination of new technologies and sustained productivity of the crop. The RYMV is highly
variable and several resistance-breaking strains have been identified. Appropriate sources of resistance to RYMV
should be identified and characterised in order to pyramid genes for both complete and partial resistance. In this
study, reaction of nine (9) rice cultivars to RYMV virulent strain in Uganda was determined. Four upland and
three lowland NERICA varieties, an O. Sativa lowland variety, Gigante and IR64 were observed. Isolates of
RYMV were collected from three “hot-spots” in Uganda (Lira, Luweero and Iganga). The isolate from Iganga was
most virulent on RYMV susceptible cultivar (IR64), and thus used to constitute study treatment evaluated in the
study. Cultivars were potted and raised in a screenhouse experiment arranged in a randomised complete block
design (RCBD) with three replicates