Field experiments were carried out in 2006 and 2007 cropping seasons at the Teaching and Research Farm of the Department of Crop Science, University of Nigeria, Nsukka, to assess the earliness to flowering and the yield of two photoperiodic groups of cowpea. The experimental materials comprised of 6 cowpea accessions obtained from Plateau State and 4 accessions from Enugu State, Nigeria. The experimental design used was a Randomized Complete Block Design with the 10 accessions as treatments. The cowpea accessions differed significantly (P < 0.05) in days to flowering and other yield traits assessed. The principal component (PC) analysis revealed that the first three PC contributed 78.11% of the variability among the 10cowpea accessions evaluated. In both seasons, the most effective traits responsible for variability among the cowpea accessions in the first principal axis included number of peduncles plant-1, number of flowers plant-1, number of pods plant-1, and grain yield. On the second PC axis the cowpea accessions were differentiated on the basis of days to first and 50% flowering. The intra-population variability evaluated by hierarchial cluster analysis conducted on the quantitative traits effectively grouped the accessions into two clusters at both cropping seasons. The cluster plots showed cluster I as day neutral (DN) cowpea accessions (Akidi-ani, Akidi-enu1, Akidi-enu2 and Akidi-enu3) that flowered early (< 45 days) with poor yield components; while cluster II comprised the short day (SD) accessions (Bwa-Tal, Bwa-Chip, Gag, Gazum and Du’ut) that flowered late (> 45 days), and were prolific in the yield traits assessed. The accession, Jalbang however, alienated itself from the clusters and was genetically independent. Grain yield of the SD accessions were significantly higher (> 1000 kg ha-1) than those of the DN accessions (< 1000 kg ha-1). The accession, Gag was distinct in grain yield as it produced over 1600 kg ha-1. Pearson correlation coefficients revealed significant positive relationship between grain yield and number of peduncles plant-1(0.796**), number of flowers plant-1 (0.774**), number of pods plant-1 (0.758**) and pod length (0.728**). However, inverse relationships were obtained when days to flowering were associated with grain yield.
Key words: Accession, phenology, photoperiod, Vigna unguiculata.
Copyright © 2022 Author(s) retain the copyright of this article.
This article is published under the terms of the Creative Commons Attribution License 4.0