INTERRELATIONSHIPS BETWEEN GRAIN YIELD AND OTHER PHYSIOLOGICAL TRAITS OF COWPEA CULTIVARS

Abstract

Adequate knowledge of the interrelationships among physiological traits is essential in planning and evaluating breeding programmes for cowpea improvement. The objective of this study was to determine the interrelationships among physiological traits of thirty cowpea cultivars and identify suitable traits for indirect selection for improved crop yield. The study was conducted for two consecutive growing seasons at the Obafemi Awolowo University, Teaching and Research Farm, Ile-Ife in Nigeria. Combined analysis of variance, cluster analysis and genotype-bytrait (GT) analysis were carried out on the measured traits. Results showed significant genotype differences for all phenological and morphological traits, except grain yield and associated yield components. The GT biplot analysis revealed close associations among the phenological traits. Grain yield was positively correlated with all morphological traits except the two peduncle traits and negatively correlated with flowering traits. IT98-131-1 was the best cultivar based on multiple traits and was identified as the ideal cultivar that can be used as a reference check. Seed growth rate, yield growth rate, yield per plant, and pod weight were identified as traits that are most appropriate for indirect selection for improved grain yield of cowpea.