Genetic Variability among Six Traits in Twelve Cassava (Manihot esculenta Crantz) Genotypes in Southern Tanzania

摘要

Twelve cassava genotypes were evaluated to assess genetic variability for root yield and its components at three locations (Naliendele, Mtopwa and Nachingwea) in Southern Tanzania during 2011/2012 cropping season. Data exploited for this purpose were, number of branches per plant, plant height, root number, root weight, shoot weight and root dry matter. Genotype x location interaction was significant for all the characters studied indicating considerable influence of the environment on the expression of the traits. High heritability and relatively high genetic gain were observed in plant height (72.90% and 36.67%), stem girth (69.41% and 33.63%) and roots per plant (44.88 and 37.05%) respectively, suggesting that the traits are primarily under genetic control and that reliable selection with simple recurrent phenotypic selection would be rewarding. Most of genotypic correlations were significant and positive. Though genotypes differed significantly at (p > 0.05) for all the traits studied, two genotypes (NDL 2006/487 and NDL 2006/438) and two varieties (Kiroba and Naliendele), were found to constitute a pool of germplasm with adequate genetic variability from which selection will bring about significant progress in cassava improvement programs. Keywords: Cassava genotypes, Root yield, Genetic variability, Heritability, Genetic gain, Genetic correlations.