Status of the South American tuberous legume
Pachyrhizus tuberosus (Lam.) Spreng.
Field observations, taxonomic analysis, linguistic studies and agronomic data
on the diversity of the South American Pachyrhizus tuberosus (Lam.) Spreng.
complex with special reference to the identi®cation of two new
cultivar groups from Ecuador and Peru
MARTEN SéRENSEN* and SéREN DéYGAARD
Botanical Section, Department of Botany, Dendrology and Forest Genetics, Royal Veterinary and Agricultural
University, Frederiksberg, Denmark
JAIME E. ESTRELLA
Departamento Nacional de Recursos Fitogene
Â
ticos, Estacio
Â
n Experimental `Santa Catalina', Instituto Nacional
Auto
Â
nomo de Investigaciones Agropecuarias (INIAP), Quito, Ecuador
LARS PETER KVIST
Forestry Section, Department of Economics and Natural Resources, Royal Veterinary and Agricultural University,
Frederiksberg, Denmark
POUL ERIK NIELSEN
Research Division MAF, Vaini Research Station, Tongatapu, Tonga, South Paci®c
Received 11 June 1996; revised and accepted 21 January 1997
The tuberous legume Pachyrhizus tuberosus is found in cultivation sporadically throughout the
tropical lowlands of South America. As a result of ®eld studies conducted in Bolivia, Ecuador, Peru
and Venezuela, three distinct cultivar groups have been identi®ed. Rare references presenting further
evidence in support of this grouping, and yielding information on the cultivation history, are re-
viewed. The dierences in morphology, agricultural practices, tuberous root quality and uses have
been studied, as has the linguistic evidence of the origin and domestication processes. The herbarium
and live material have been subjected to multivariate analyses in order to establish which easily
observable phenotypic characters can be used in the identi®cation of the three cultivar groups. This
paper reports on the analysis of 23 morphological characteristics from 31 P. tuberosus cultivar
records. The considerable potential of this cultivar/landrace complex and the possibilities of es-
tablishing in situ conservation initiatives are discussed.
Keywords: agricultural practices; in situ conservation; linguistic evidence; Pachyrhizus tuberosus
landraces; South America; leguminous tuber/root crop; principal component analysis.
El cultivo de la leguminosa tuberõ
Â
fera Pachyrhizus tuberosus se distribuye espora
Â
dicamente a lo largo
de las regiones tropicales y subtropicales de Ame
Â
rica del Sur. Como resultado de exploraciones y
estudios de campo en Bolivia, Ecuador, Peru y Venezuela se han identi®cado tres distintos grupos de
cultivares. Este artõ
Â
culo analiza numerosa informacio
Â
n y evidencias ine
Â
ditas que caracterizan a
dichos grupos de cultivares y su historia en cultivo. Se estudia adema
Â
s las diferencias en morfologõ
Â
a,
pra
Â
cticas culturales, calidad de la raõ
Â
z tuberõ
Â
fera y sus usos, asõ
Â
como tambie
Â
n la evidencia lingu
È
õ
Â
stica
* To whom correspondence should be addressed.
0960-3115 Ó 1997 Chapman & Hall
Biodiversity and Conservation 6, 1581±1625 (1997)