Estimation of the extent of phenotypic diversity among cashew (Anacardium occidentaleL.) genotypes based on agro-morphological and physicochemical traits

Abstract

Cashew (Anacardium occidentale L.) is cultivated in more than 30 countries because of its economic and nutritional importance. Despite having a significant agronomic role, little is known about the genetic and phenotypic diversity of cashew populations in Brazil. Thus, we aimed to characterize and estimate the diversity among cashew genotypes based on agro-morphological and physicochemical traits, with an objective of selection of varieties for breeding programmes. Forty-three cashew trees were evaluated based on 13 morphological traits and three physicochemical traits. A wide range of variations was recorded for the phenotypic characteristics, including total weight, fruit weight, pseudofruit length, kernel weight and total acidity, suggesting the existence of considerable variations for potential use in breeding programmes. Principal component analysis explained 79.74% of the total variation in the first two principal axes. The dendrogram based on the UPGMA method classified the 43 genotypes into six groups. Groups IV and VI were the most dissimilar, with emphasis on the genotypes 28 and 43, which were observed to be most divergent based on the Euclidean distance matrix (3.054). This makes it possible to select genotypes for hybridization with F1 generation gains. Based on cluster analysis and comparison of means among the six groups, promising genotypes were identified with superior traits, such as fruit weight, pseudofruit length, kernel weight and total acidity. This suggests the importance of phenotypic characterization for cashew breeding programmes. In addition, the observed vast diversity is an important genetic basis for improving cashew yield in northeastern Brazil.