Agronomic performance of three cocoyam (<Emphasis Type="Italic">Xanthosoma violaceum</Emphasis> Schott) genotypes grown in Nicaragua

Cocoyam (Xanthosoma spp.), the third most important starch food crop in Nicaragua, can be cultivated countrywide. However, very little information about the field performance and genetic background of the different genotypes is available. In this study, the agronomic performance of three purple genotypes established in four locations with different climatic conditions, were evaluated during 2 years. Phenotypic characteristics, yield, and virus incidence were assessed and the time at which the different genotypes reached their physiological maturity was estimated. The trials were based on randomized complete block design with three or four blocks. Genotype × location interaction was found both for phenotypic and yield traits. A differential response of the genotypes to the varying climatic conditions at the locations is suggested to be one of the causes to the interaction. The unpredictable and variable climate in the area where cocoyam traditionally has been grown is one possible explanation to the frequent genotype × year interaction at that location. Other locations with more stable climate only showed an interaction between genotype and year in a few traits. The genotypic differences regarding the time when the area of the largest leaf reached its maximum and the variation in presence of sprouts and roots on the cormels at harvest, indicate differences in optimal harvest time between genotypes. The percentage of plants infected with dasheen mosaic virus (DMV) differed across locations but not between genotypes.