Effect Of Genotype X Environment Interaction On Yield And Yield Components Of Cassava (Manihot Esculenta Crantz) Genotypes In The Southern Zone Of Tanzania

ABSTRACT

Cassava (Manihot esculenta Crantz) is a food security crop for most of the populations in the tropical regions of the world, where it ranks fourth as a source of energy, after rice, sugar cane and maize. Twelve cassava genotypes were evaluated to assess genetic variability for root yield and its components at three locations (Naliendele, Mtopwa and Nachingwea) in the Southern zone of Tanzania, during 2011 - 2012 cropping season. This research was carried out to study the stability performance for cassava root yield and its components using a Randomized Complete Block Design under split-split plot experiment. Genotype x location interaction was significant for all the characters studied, indicating considerable influence of the environment on the expression of the traits. Stable genotypes were identified for wider environments and specific environments with high per se performance for root yield per plant. The investigation revealed that, Kiroba (21.72 t ha-1 ) and NDL 2006/487 (19.5 t ha-1 ) were desirable and relatively stable across the environments. The genotype NDL 2006/850 was suitable for favourable situations, while genotypes NDL 2006/104 and NDL 2006/283 were suited to poor environments for root yield. High heritability and genetic gain were observed in plant height (0.729 and 36.67%), stem girth (0.694 and 33.63%) and roots per plant (0.449 and 37.05%) suggesting that the traits are primarily under genetic control and that reliable selection with simple recurrent phenotypic selection would be rewarding. Though genotypes differed significantly for all the traits varieties Kiroba and Naliendele; genotypes NDL 2006/487, NDL 2006/283, NDL 2006/104 and NDL 2006/850 were observed to constitute a pool of germplasm with adequate genetic variability, from which selection will bring about significant progress in cassava improvement programmes.