Assessment of Genetic Biodiversity of Nigerian Cashew (Anacardium occidentale L.) Accessions using Morphological and Anatomical Traits

Abstract

The genetic diversity and relationship among 20 accessions of cashew were evaluated in order to provide useful information for selecting good yield of cashew germplasm that will produce nuts of high marketable value. The principal component analysis (PCA) revealed that morphological features such as leaf length, leaf width and petiole length; as well as anatomical attributes such as stomatal complex type, stomatal density and stomatal index accounted for most of the variation. Leaf anatomical traits portrayed higher genetic similarity (93.65%) than the morphological features (50.00%) among the cashew accessions based on the unweighted pair group method of arithmetic averages (UPGMA), which grouped the 20 accessions into two main clusters and several sub clusters; thereby signifying polymorphism among accessions. The different sub-clusters of cashew accessions suggest that genetic variation occurred among them. The study portrayed that accessions OGD 003, KMB 004, SOB 005, OGD 004, OGD 002 and UNI 002 showed potentials for selection using the morphological traits such as leaf length, leaf breadth, petiole length and nut weight; while accessions UNI 003, UNI 004, SOB 003, OGD 003, KMB 003 and KMB 004 showed potentials for selection using the anatomical attributes such as stomatal density, stomatal index, stomatal complex types and moderate stomatal size due to their high genetic variation. This information will be beneficial for tree improvement programme in cashew nuts.