Caracterização e avaliação morfoagronômica de variedades tradicionais de feijão-caupi em Manaus, AM

Abstract

Cowpea (Vigna unguiculata (L.) Walp) is a legume of great nutritional and economic importance, native to Africa and widely cultivated in Brazil, especially in the North and Northeast regions. Due to the species’ wide genetic variability and high adaptability, there is growing interest in obtaining morphological and agronomic information, which is essential for supporting genetic improvement programs. However, studies on these traits in traditional cowpea varieties under the edaphoclimatic conditions of Manaus, Amazonas, remain scarce. In this regard, the objective of this study was to characterize and evaluate traditional cowpea varieties in a dryland area in Manaus, Amazonas. The samples consisted of seeds from the cowpea collection maintained by the Active Germplasm Bank of the National Institute for Amazonian Research (INPA). The experiments employed a randomized block design with a factorial layout of 16 treatments (traditional varieties) × 2 (growing seasons), with four replications, in which 31 qualitative and quantitative descriptors were evaluated. For the morphological descriptors, the mean values obtained from the two growing seasons were used. The qualitative data were described and, when necessary, subjected to descriptive statistical analysis. The quantitative data were subjected to analysis of variance and the Scott-Knott test at a 5% significance level. To study genetic diversity, the Mahalanobis dissimilarity matrix and the simple coincidence measure were used. The treatments were clustered using the Unweighted Pair Group Method with Arithmetic Mean (UPGMA) and Tocher’s hierarchical agglomerative method. The relative importance of the descriptors for genetic divergence was determined using Singh’s method. In the evaluation of productive performance, a factorial design was adopted comprising the 16 varieties and two growing seasons (rainy season and dry season), followed by analysis of variance and the Scott-Knott test at a 5% significance level. Pearson’s correlation was also performed among the yield components (t-test, 5%). The results revealed genetic variability among the 16 traditional varieties evaluated. The clustering methods used identified 3 and 4 groups. The variables that contributed most to the dissimilarity among the evaluated varieties were the number of main branches, seed width, pod length, and apical leaflet width. There were significant differences among the cowpea varieties, across growing seasons, and for the cultivar × growing season interaction for all response variables analyzed. During the rainy season, the grain yield of the CFG variety stood out, at 1,467.03 kg ha−1. In the rainy season, yield correlated positively with the number of pods per plant, the number of seeds per pod, and the seed mass per plant, whereas in the dry season, negative correlations predominated, especially for the number of seeds per pod and the average pod weight.