Phenotypic characterization of the traditional cashew (Anacardium occidentale L.) populations from Nachingwea and Newala districts, Tanzania

This study was conducted to assess phenotypic variation in traditional cashew populations from Nachingwea and Newala districts in Tanzania. A total of 120 traditional cashew trees were sampled from the two districts, with 60 samples from each study site. Morphological descriptors for cashew developed by the International Board for Plant and Genetic Resources (IBPGR) in 1986 were used for the phenotypic characterization of traditional cashew populations. The study revealed high phenotypic variation within populations and relatively low variation between populations. The four characters, namely leaf shape, leaf apex, angle of leaf petioles, and crotch angle exhibited highest levels of phenotypic variation. A dendrogram generated from the phenotypic (morphological) data based on Unweighted Pair Group Method with Arithmetic mean (UPGMA) grouped individuals from the two traditional cashew populations into two major clusters. Additionally, in the Principal Coordinates Analysis and Linear Discriminant Analysis most of the traditional cashew individuals from the two study sites clustered irrespective of their geographic origin. Moreover, the high levels of genetic variation revealed within each of the two traditional cashew populations imply that the traditional cashews from both populations are potentially important for cashew breeding programs. Therefore, in-situ and ex-situ conservation of traditional cashew germplasm from the two populations is important for sustainable cashew breeding.