Within-family genetic variation and epistasis in cassava (Manihot esculenta Crantz) adapted to the acid-soils environment

Pérez Velásquez, Juan Carlos; Ceballos, H.; Calle, F.; Morante, N; Gaitan, W; Llano Rodríguez, Germán Alberto; Álvarez, E.

Within-family genetic variation and epistasis in cassava (Manihot esculenta Crantz) adapted to the acid-soils environment

2005

Little is known about the inheritance of agronomic traits in cassava, or on the relative importance of epistasis for most crops. A group of 10 clones, adapted to the acid-soils environment was used as parents in a diallel study. Thirty genotypes were obtained from each F1 cross and cloned. Each clone was represented by six plants, which were distributed in three replications at two contrasting locations. Genetic variability concentrated in the within-family component, which was statistically significant for all the variables analyzed (fresh root yield (FRY), fresh foliage yield (FFY), harvest index, root dry matter content, and plant type score (PTS)) except for the reaction to super elongation disease (SED). Estimates of dominance variance were considerably larger than those of additive variance for fresh root and foliage yields. The reverse was observed for harvest index, dry matter content, PTS and SED score. Epistasis played an important role only for fresh root and foliage productions. These results agree with those from similar studies targeting different environments. The common assumption of absence of significant epistatic effects frequent in many quantitative genetic designs is, therefore, challenged from the results for these two variables. Alternative breeding approaches are suggested according to the results obtained from this study.

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