Euphytica (2005) 142: 265–272
DOI: 10.1007/s10681-005-2147-5
C
Springer 2005
Agronomic performance of three cocoyam (Xanthosoma violaceum Schott)
genotypes grown in Nicaragua
G. ReyesCastro
1,2
,M.Nyman
1,∗
& A.C. R¨onnberg-W¨astljung
1
1
Department of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, P.O. Box 7080,
SE-750 07, Uppsala, Sweden;
2
Universidad Nacional Agraria, Box 453, Managua, Nicaragua;
(
∗
author for correspondence: e-mail: Marie.Nyman@vbsg.slu.se)
Received 24 December 2003; accepted 14 February 2005
Key words: dasheen mosaic virus (DMV), genotypes, G × L interaction, harvest time, morphology, yield
Summary
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.
Introduction
Cocoyam (Xanthosoma spp.) is a staple root crop that
belongs to the Araceae family. It is native to trop-
ical Central and South America and the Caribbean
(Montaldo, 1991), and different species within the
genus Xanthosoma have been cultivated and consumed
since the pre-Columbian epoch (L´opez et al., 1995).
Cocoyam is an important crop in tropical and subtrop-
ical areas because it provides carbohydrates, proteins,
fat and vitamins (Wilson, 1984; Tambong et al., 1997;
Torres et al., 1994), and a cash income for the farm-
ers (Tambong et al., 1997; Lebot & Aradhya, 1991;
Onokpise et al., 1999). In Nicaragua it is the third most
important starch crop after potato (Solanum tuberosum)
and cassava (Manihot esculenta).
The major cocoyam producing areas in Nicaragua
are located in the humid zones and the production
relies on small farmers having 0.5–2.0 ha in produc-
tion. The production area in Nicaragua has decreased
drastically during the last few years, from 30,000 ha
in year 2001 to 13,000 ha in year 2002, a decrease
that is mainly due to diseases, and unstable prices
(MAG-FOR, 2003). The demand for fresh cocoyam
has, however, gradually been increasing in Europe and
in the United States, and recently, farmers in non-
traditional cocoyam-producing areas (northwestern dry
zones) have started to establish small commercial areas
to expand the production for export.
Although it is an important staple food crop in many
tropical countries, cocoyam has received low research
priority (Goenaga & Hepperly, 1990). In 1975 The