ABSTRACTGroundnut production is largely constrained by biotic stresses with groundnut rosette virus disease seriously contributing to losses in yield in Nigeria and sub Saharan Africa and thus the need to study the mode of inheritance of aphid and rosette resistance in groundnut with these objectives; to investigate the gene action controlling the inheritance of aphid resistance, rosette resistance and other quantitative characters, to determine the relationship between aphid resistance, rosette resistance and other quantitative characters, to estimate the number of effective factors controlling the inheritance of aphid infestation, rosette disease and other quantitative characters and to determine genetic advance arising from selection against aphid resistance, rosette resistance and other quantitative characters. For this, two aphid resistance (ICGX-SM00020/5/9, P1 and ICGX-SM0020/5/P4/P1, P2), one rosette resistance, ICVIS07899 (P3) and one aphid susceptible, ICGX-SM0027/5/P10/P1 (P4), one rosette susceptible, Manipenta (P5) lines were used as parents to develop F1s. The F1s were advanced to F2s and backcrosses made to the reciprocal recurrent parents. The seventeen generations obtained were evaluated along with three checks (Samnut 24, Samnut 25 and Samnut 26) in three replications using randomized complete block design at Institute of Agricultural Research Samaru, Zaria during 2014 growing season. Significant differences in mean performance among the parents and the F1s studied suggests sufficient variability across the generations for the characters studied. The three parameter model was adequate to explain variations observed in the inheritance of days to fifty percent flowering, plant height, number of seeds per plant and shelling percentage. It was inadequate to explain the variations observed in the inheritance of aphid infestation index, rosette disease incidence, rosette severity index, days to maturity, number of matured pods per plant, pod yield per plant and hundred seed weight hence, six parameter model was fitted. Non allelic vii gene interactions were significant for number of matured pods per plant, pod yield per plant, rosette disease severity and rosette disease incidence. Dominance genes and epistasis bias the number of effective factors for days to fifty percent flowering, plant height, number of seeds per plant, shelling percentage, rosette disease incidence, rosette severity index, number of matured pods per plant and pod yield per plant hence, rendering the estimates less reliable. Wide ranges of narrow (33 to 95%) and broad (0 to 93%) sense heritability as well as genetic advance (0 to 32.3) were obtained for the characters studied. The genotypic correlation coefficients exceeded those of the corresponding phenotypic correlation coefficients for most of the character pairs indicating that the correlations were more genetic than environmental in the three sets of crosses. In conclusion, the set of groundnut crosses where non allelic interaction was significant with high narrow-sense heritability as obtained for rosette disease incidence, rosette severity index, number of matured pods per plant and pod yield per plant, it is possible to expect advance for these characters in further segregating generations. Broad sense and narrow sense heritability as well as genetic advance were moderate to high for most of the characters studied for the three sets of groundnut crosses. Genotypic coefficients of correlation were higher than phenotypic coefficients of correlation.
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