Genotype x environment interaction on performance of selected cashew (Anacardium occidentale L.) hybrids in Tanzania

A DISSERTATION SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN CROP SCIENCE OF SOKOINE UNIVERSITY OF AGRICULTURE. MOROGORO, TANZANIA.Cashew (Anacardium occidentale L.) is an important export crop in a number of tropical countries and is the main cash crop and the leading source of income for over 300,000 households in Southern and Eastern Tanzania. Farmers still, however use unimproved varieties, which account for low yields. Thirty cashew genotypes were evaluated to assess genetic variability for higher yield and its components at two locations (Nachingwea and Chambezi) in the Southern and Eastern zones of Tanzania, respectively, during the 2014/2015 production season. The experiment was laid out in Randomized Complete Block Design with three replications. Genotype x location interaction was significant for all agronomic characters studied and all nutritional characters except Calcium and Sodium contents, indicating influence of the environment on the expression of most traits. High yielding genotypes with broad adaptation and some with specific adaptation were identified. Of these, H3, H5, H6, H15, H16, H22, H23, H24, H26, H27 and H29 were adapted to varying environments. In the contrary, high yielding unstable hybrids H2, H4, H7, H18, H19, H25 and H30 were more suitable for Nachingwea site while H1, H8, H10, H11, H13 and H17 were more favourable for Chambezi site. H22, H5 and H24 were identified as the best in stability, yield with good agronomic and nutritional attributes and tolerance to blight disease. Growing for nutritional quality, hybrid H1 was more favorable in a number of variables such as protein, fat, potassium, copper, iron, zinc and vitamin C. Among the least stable hybrids in yield, H4, H8, H17, H11, H18 and H30 had high yields with good agronomic and nutritional traits. Others, H28, H12 and H9 appeared to be stable but recorded low yields. Therefore crosses between these two groups will combine stability and yield in the same background