NODULATION EFFICIENCY AND YIELD COMPONENTS IN COWPEA (Vigna unguiculata L. Walp.) VARIETIES CULTIVATED IN SOUTHWESTERN NIGERIA

Abstract

There is limited information on the genetic variability and relationship between nodulation traits and yield components in cowpea. This study aimed to examine the genetic variability, nexus between nodulation parameters and key yield components; identify important traits for selection in developing high-yielding cowpea varieties with efficient nodulation, and varieties that combine both high grain yield and high relative nodulation efficiency (RNE). Fifty cowpea varieties were evaluated using a randomised complete block design in three replications. The experiment was conducted at the Obafemi Awolowo University Teaching and Research Farm, Ile-Ife, Nigeria. Data were collected on agronomic traits, grain yield, and nodulation parameters. Pearson’s correlation was used to assess relationships among these traits. Fisher’s least significant difference (LSD) was used to compare means at P ≤ 0.05. Results showed significant variability among germplasm and correlations between some nodulation parameters and yield traits. Root dry weight was positively correlated with pod length and grain yield. Root fresh weight also showed a significant correlation with grain yield. Shoot dry weight correlated positively with the number of peduncles. It was inferred that there existed wide variability among the germplasm, a strong association between grain yield and RNE; and root and shoot biomass, nodule dry weight and pod length are major traits to be considered for selection in developing high-yielding cowpea with high RNE. Ife Brown, IT10K-817-7, and Oloyin were found to combine high grain yield with high RNE.