Abstract
Groundnut chlorotic rosette disease (GCRD) transmitted by the aphid, Aphis craccivora, is an important virus disease of groundnut in Africa. Breeding for host resistance remains the best strategy to minimize losses due to this disease. Nine cultivated groundnut genotypes with differential reaction to GCRD were crossed in an incomplete diallel mating design to determine the combining ability of GCRD resistance. The parents and 36 F2 populations were inoculated with veruliferous A. craccivora at the seedling stage and evaluated for disease reaction at two locations in Nigeria in 2012. Disease incidence (based on visual symptoms) was recorded three times at fortnightly interval using area under disease progress curve. General combining ability (GCA) and specific combining ability (SCA) effects for GCRD resistance were highly significant (P < 0.01), indicating that both additive and non-additive gene effects governed the inheritance of GCRD resistance. The Baker ratio was low (0.3) for GCRD indicating that non-additive gene effects was more important than additive gene effects in controlling GCRD resistance in these crosses. As a result, progeny performance could not be adequately predicted from GCA effects alone. Therefore, effective selection of superior genotypes would be achieved at advanced generations when maximum homozygosity is attained. Key words: Groundnut chlorotic rosette disease, area under disease progress curve, combining ability, additive and non-additive gene effects.
Highlights
Groundnut (Arachis hypogaea L.), is cultivated annually on about 24.63 million hectares worldwide with annual production of 41.27 million tons in shell with a productivity–1 of about 1.85 t ha (FAO, 2012)
These results indicate resistance of these progenies was higher than would be expected from average of their expected parents based on area under disease progressive curve (AUDPC) symptom rating
The estimates of low values of ratio of combining ability variance indicated that nonadditive gene effects were more important than additive gene effects in determining
Summary
Groundnut (Arachis hypogaea L.), is cultivated annually on about 24.63 million hectares worldwide with annual production of 41.27 million tons in shell with a productivity–1 of about 1.85 t ha (FAO, 2012). Groundnut (Arachis hypogaea L.), is cultivated annually on about 24.63 million hectares worldwide with annual production of 41.27 million tons in shell with a productivity. It is highly adapted to tropical and subtropical climates of the world and cultivated in nearly 100 countries. It is a key crop for small scale farmers especially in Africa and Asia where the crop serve as a valuable source of dietary protein, oil, and fodder for livestock.
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