Grain yield and plant morphology of cowpea genotypes with different planting densities under irrigated and rainfed conditions

The objective of this study was to evaluate the effect of planting densities on yield and on plant architecture of different genotypes of cowpea (Vigna unguiculata L. Walp.) when cultivated under irrigated and rainfed conditions. The genotypes IT 86D-472, Epace 10 and TE 90-180-27F, semi-upright, semi-spreading and spreading growth habits, respectively, were evaluated in five different populations, in a randomized block design, with three replications, at Petrolina, PE, Brazil. The analysis of variance showed significance for genotypes and no significance for genotype x plant population interaction for all characters. The lack of significance in grain production occurred because the genotype Epace 10 showed superiority in all five populations. The genotypes showed non-significant tendency to decrease the length and number of nodes in main branches, to increase the height of first pods from the soil and to decrease the number of secondary branches (P<0.05), when cultivated in higher populations in both environments. IT 86D-472 showed significance to populations and the highest grain yields were obtained with 207,328 and 203,051 plants/ha under irrigated and rainfed conditions, respectively. Epace 10 and TE 90-180-27F did not show significance when cultivated under different populations, in both environments.