Fig. 1. Yellow-seed cultivars analyzed in this study. Mayocoba (MX 1959) and Canario (PE) are representative of the parents that gave rise to the Peruano type cultivar class. Examples of this class are the Mexican cultivars Azufrado Pimono 78 (the original Peruano-type cultivar released in 1978) and Azufrado Peruano 87 (released in 1987) (Voysest, 2000). Enola is a patented and PVP certified yellow-seeded cultivar (Proctor, 1999; http://www.ars-grin.gov/cgi-bin/npgs/html/acchtml.pl? 1536394; verified 27 January 2004). Sulphur BN142 is an ancient U.S. cultivar described as early as 1931 (Hedrick 1931).