For plant genetic improvement, it is paramount to determine genetic components for the selection of desirable traits. Eighteen Amaranthus cruentus and 11 Amaranthus hypochondriacus genotypes were evaluated at two locations in Nigeria differing in temperature/precipitation to determine the influence of environment on genetic gain. Genotype × environment was significant for all analysed morphological parameters and for grain yield, 1000 seed weight and no. of days to 50% flowering in A. cruentus. In A. hypochondriacus genotype × environment was significant for plant height, leaf length and width, leaf area, inflorescence length, 1000 seed weight and grain yield. Higher genotypic coefficient of variability, heritability estimates, and genetic advance was observed for the traits at Abeokuta (more wet) than Ibadan (more dry) conditions. Grain yield had positive association with the traits at the two locations except the number of leaves and inflorescence length. Inflorescence length was positively associated with grain yield at Abeokuta and negatively associated at Ibadan. Path analysis indicated simultaneous improvement of grain yield with petiole length and leaf length at Abeokuta but with petiole length and leaf area at Ibadan. In general, the locations had potential for genetic improvement of traits of amaranth grain; therefore, selection criteria for improving grain yield should be considered with respect to environment.
