MORPHOLOGICAL DIVERSITY IN LANDRACES OF COMMON AND RUNNER BEANS FROM THE EASTERN MÉXICO STATE

Abstract

México is center of origin, domestication and diversification of common (Phaseolus vulgaris L.) and runner (P. coccineus L.) beans.
Both species together with maize (Zea mays L.) have been of nutritional importance since pre-hispanic times. The phenotypic and genetic diversity of these crops is currently conserved in native populations grown by farmers. The need to generate strategies to optimize the in situ conservation and to diminish the apparent genetic erosion of both species in the eastern region of the State of México and north of Morelos motivated the study of the morphological diversity contained in P. coccineus and P. vulgaris from this region. We characterized 107 populations of common bean, 42 of runner bean and one of P. coccineus ssp. darwinianus, through 11 qualitative and 16 quantitative traits. The variation among common bean populations was larger than that of runner bean populations for flower color, form and seed color, and for the predominant pod peak shape. The runner bean populations had larger variation in seed size than in seed color (54.8 % purple, 26.2 % black and 19.0 % white and brown), and two groups were distinguished (early and late) based on days to flowering, seeds per pod and seed size. It was concluded that there still is large
diversity available, in common bean, more than in runner bean, which may be due to seed exchange in regional markets and the
maize-bean intercrop.