Characterization and analysis of North American triticale genetic resources

A collection of more than 3000 secessions of triticale (x Triticosecale Wittmack), called the North American Triticale Genetic Resources Collection (NATGRC), was assembled from 10 active and inactive breeding programs in the USA, Canada, and Mexico for the purposes of conservation, characterization, evaluation, and documentation. Since triticale has no wild ancestors and hybrid parentage is often unknown, preservation of unique gene combinations is essential for continued utilization. The origin groups that comprised the whole collection were evaluated in field plots for 2 yr at Davis, CA. Accessions were predominantly secondary hexaploid triticaIes having spring growth habit. The collection was classified for spike type and 38% had spikes typical of complete (Beagle type) and 30% were substituted (Armadillo type) triticale. The Shannon-Weaver diversity index (H'), computed for seven qualitative traits, was 1.275 for the whole collection. The most diverse group was from Manitoba (1.404) and the least diverse groups were from Oregon (0.822) and CIMMYT (0.867). Over-trait mean coefficients of variation for eight quantitative traits gave similar diversity ratings as H' for each of the origin groups (r = 0.74*), suggesting that simply scored traits may be useful for assessing overall diversity in large genetic resource collections. Principal components (PC) analysis of quantitative traits showed differentiation, but considerable commonality, among the Canada, Mexico, and USA groups. The CA-Davis group included hybrid derivatives from CA-Jenkins x CIMMYT groups that clustered intermediate to those groups, suggesting a genetic basis for the phenotypic clustering. The PC analysis showed that the Beagle and Armadillo types differed in several quantitative traits, showing that this classification is a useful descriptor for hexaploid triticale. The NATGRC is conserved at USDA, Aberdeen, LD, and CIMMYT, Mexico. Researchers are urged to use and contribute to this collection. The formation of a European-based collection emphasizing winter growth habit is recommended.