Multi-Trait Evaluation of Cashew Clones for Reproductive Efficiency, Nut Quality, and Morphological Diversity

Abstract

Cashew (Anacardium occidentale L.) production in Nigeria is hindered by the limited use of improved varieties, whose nut quality and reproductive performance have been well documented. This study evaluated twelve cashew clones from the Cocoa Research Institute of Nigeria (CRIN) germplasm collection for nut quality, pollen viability, and morphological traits. Analysis of variance, Pearson correlation, principal component analysis, and a multi-trait performance index were used. Significant genetic variation was found across all traits. Nut weight ranged from 4.27 g (EU202) to 11.34 g (OCJ9), while kernel weight ranged from 1.50 g (EU202) to 3.75 g (OCJ9). Positive correlations (r > 0.96) between nut weight, kernel weight, and nut length confirmed that selecting for any of these traits will improve the others simultaneously. Shelling percentage was negatively correlated with nut size (r = -0.719), showing a size-efficiency trade-off. Pollen tube length and germination percentage varied independently from nut size and kernel recovery traits (nut weight, kernel weight, and nut length). This independence means that reproductive efficiency and nut size traits can each be improved without compromising the other. Principal component analysis separated a nut size efficiency axis from a reproductive-morphological axis, showing multi-dimensional diversity. The multi-trait performance index ranked OCJ9 first (index = 3.45), combining the largest nut size (11.34 g), the highest kernel weight (3.75 g), and good pollen performance. ORO3 ranked second (index = 1.44) for its outstanding pollen germination (98.00%) and pollen tube length (133.33 μm), and YS103 ranked third (index = 0.75) with the highest germination rate (98.50%). BEL22 ranked fourth overall. These clones are recommended as priority parents for cashew improvement in Nigeria.