Genotype x environment effects on cassava response to the green mite (Mononychellus tanajoa)

Nukenine, E., Dixon, A. & Ngeve, J. (2002). Genotype x environment effects on cassava response to the green mite (Mononychellus tanajoa). African Journal of Root and Tuber Crops, 5(1), 3-8.

Genotype x environment (G x E) interactions frequently complicate breeding efforts and delay progress in selection. The cassava green spider mite (CGM) (Mononychellus tanajoa Bondar) is a serious constraint to Cassava production in Africa. Nine cassava genotypes were grown at 6 representative locations for 3 years to study G x E interaction patterns for tile reaction of cassava genotypes to CGM, and to identify genotypes with stability to the pest, using the Additive Main Effects and Multiplicative Interaction (AMMI) statistical model Environments, genotypes and G x E interactions were highly significant (P < 0.01) for the pest. The G x E interactions accounted for 24.7%, of the treatment sum of squares for CGM

and influenced the relative ranking of genotypes across environments. The magnitude 01 the G x E interaction effect for CGM was higher than that for genotypes. Clone 63397 had the smallest interaction for CGM, showing stability in response to the pest across agroecologies. TME 1 suffered the least damage across the 18 environments. Examination of the G x E interaction structure revealed specific areas where screening of cassava genotypes for resistance to the cassava green mite could be best done.