Agro-morphological characterization of preselected cashew (Anacardium occidentale L.) mother trees in Benin farmer's plantations

Abstract

One of the main causes of low cashew nut yields in African countries is the lack of improved planting materials used for plantation establishment. It is therefore necessary to efficiently select planting material to increase cashew nut yields. The objective of this study was to assess the agro-morphological diversity of preselected cashew mother trees for facilitating their further selection in cashew plantations in Benin. Thirty-one variables were measured. These variables, including 12 quantitative and 19 qualitative, were selected in cashew descriptors developed by Bioversity International. Statistical tools were performed for the assessment of the 394 cashew mother trees preselected in 23 administrative districts originating from the four major cashew nut production regions in Benin: Atacora-Donga, Borgou, Zou-Collines and Plateau. A Factorial Analysis on Mixed Data and a Hierarchical Cluster Analysis (HCA) were carried out to group the individuals. Finally, a morpho-metric characterization of the different groups based on quantitative discriminant descriptors from a multivariate analysis of variance (MANOVA) was carried out. The HCA result on mixed data showed three significant morpho-metric groups of cashew mother trees. Discriminant stepwise analysis carried out on all 31 morpho-metric descriptors showed that 15 were found to be the most discriminating (5 quantitative and 10 qualitative descriptors) of the morpho-metric groups (P ˂ 0.001). The leave vein crossing, hermaphrodite flower rate, apples unit weight, abnormal flower number and nut basis shape showed significant positive or negative correlations. These results suggest the existence of an important phenotypic variability among Beninese cashew accessions that could be used in cashew tree breeding program being implemented in Benin.