Phenotypic variation in a core collection of common bean (Phaseolus vulgaris L.) in the Netherlands

Forty accessions, forming a core collection of mainly bush type of the comm on bean ( Phaseolus vulgaris L.) germplasm in the Netherlands, were evaluat ed for 14 qualitative and quantitative traits at the Agricultural Universit y, Wageningen (WAU), the Netherlands in 1992. These and an additional 117 D utch accessions, mainly collected in private home gardens, were also evalua ted for phaseolin seed protein pattern, and morphological and agronomic tra its at the International Center for Tropical Agriculture (CIAT, Spanish acr onym), Cali, Columbia between 1987 and 1997. Multivariate and principal com ponent analyses at both WAU and CIAT indicated existence of one large group with no discernable patterns among Dutch common bean collections of landra ces, garden forms and cultivars. However, when phaseolin, an evolutionary, biochemical marker, was used as an initial classification criterion followe d by use of morphological markers, the two major gene pools; Andean and Mid dle American with two races in each (Chile and Nueva Granada in Andean, and Durango and Mesoamerica in Middle American) were identified. The Andean ge ne pool was predominant (136 of 157 accessions), especially the race Nueva Granada (126 accessions) characterized by the bush determinate growth habit type I and T phaseolin. The new core collection comprised 31 accessions. B ean races Chile, Durango, and Mesoamerica were represented by 10, 7, and 14 accessions, respectively. Of the 9 French or snap bean accessions six poss essed characteristics of race Mesoamerica and three belonged to Durango rac e. Occurrence of these and a large number of other recombinants strongly su ggested considerable hybridization and gene exchange between Andean and Mid dle American gene pools, thus blurring the natural boundaries and forming a large single group of common bean germplasm in the Netherlands. The inter- gene-pool recombinants of both dry and French beans should be of special in terest to breeders for use as bridging-parents for development of broad-bas ed populations.