Abstract:
Rice is consumed by over half of the world’s population and accounts for 19% of calorie intake. Biotic stresses cause substantial yield losses in rice. Rice blast and Rice yellow mottle disease (RYMD) are the two main biotic stressors in sub-Saharan Africa. In Ghana, the major rice varieties cultivated by farmers namely, CRI-Agra Rice, CRI-Amankwatia, Jasmine 85 and Togo Marshall are susceptible to blast and Rice yellow mottle virus (RYMV) diseases and can cause up to 100% yield losses. There is thus the need to tackle these two diseases in order to reduce these yield losses. The objective of this research was to introgress resistance genes for rice blast and RYMD into four popular aromatic rice varieties in Ghana. To achieve this objective, a donor parent, Gigante which had RYMV1 (rymv1-2) and blast (Pi54) resistance genes was crossed to the four popular aromatic rice varieties to produce BC3F2 populations. A total of 71 BC3F2 rymv1-2 and Pi54 introgressed lines were screened for resistance to RYMV and blast and evaluated in a Preliminary Yield Trial (PYT). All the lines were found to be highly resistant to RYMV and rice blast. The results of the PYT indicated that RYMV-B-03-84-36-10-57, RYMV-B-01-6-37-1-91 and RYMV-B-03-84-36-10-46 yielded 7.25 ton/ha, 7.23 ton/ha, and 7.12 ton/ha respectively, which were significantly higher (P<0.05) than the highest yielding recurrent parent, CRI-Agra Rice (7.09 ton/ha). Through marker-assisted backcrossing, lines that are resistant to rice blast and Rice yellow mottle disease were produced. These can be evaluated further and released as resistant versions of the four popular but susceptible aromatic varieties.
