Selection of cassava clones for high fresh root yield and root starch content with stability of performance under Malaysian conditions†

S. L. Tan and C. Mak

Abstract

Fifteen genotypes of cassava were tested for two seasons in each of six locations (representing mineral soils and drained peat as well as three agro-ecological zones [AEZ]), and data collected on fresh root yield and root starch content. Highest fresh yield and starch content was recorded at Serdang (mineral soil, AEZ 3 with no distinct dry season). However, peat locations were capable of productivity and starch content equivalent to the mineral soil locations. CM 982-7 produced the highest genotype mean for yield over all locations. With its moderately low root cyanide content, this genotype is suitable for eating. However, because of its low starch content, this genotype is not as good as 17/A and Black Twig for planting on mineral soils, nor CM 982-2 for peat. Stability analyses using Shukla’s variance statistic σ_i², rank-sum indices and Hüh’s non-parametric statistics s_i³ and s_i⁶ showed all three methods were in agreement in selecting Black Twig for being stable for moderately high root yield and starch content. The parameters s_i ³ and s_i ⁶ in selecting genotypes stable for fresh yield and starch content were not so successful in ensuring these had the desired high values for the two traits.

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