CHARACTERS RELATED TO LEAF PHOTOSYNTHESIS IN WILD POPULATIONS AND LANDRACES OF COMMON BEAN

Wild populations of common bean (Phaseolus vulgaris L.) vary in charac ters related to leaf photosynthesis. To investigate if such variation exists in leaf photosynthetic characteristics of landraces, and if wil d accessions are similar to landraces within a region of origin, 47 wi ld populations and 47 landraces were evaluated in two held experiments in Colombia. Young unshaded fully expanded leaves of each accession w ere used to measure stomatal density, CO2 exchange rates (CER), stomat al conductance, chlorophyll, soluble protein, and N content. As a grou p Andean accessions (both wild and landraces) had lower specific leaf weight, less chlorophyll, lower CER, lower stomatal conductance, less stomatal density, and higher N content as compared with Mesoamerican a ccessions. The Andean landraces had the lowest CER as opposed to Mesoa merican landraces which had the highest CER value. For most of the var iables measured, univariate analysis of variance within a country of o rigin suggested that landraces were similar to wild populations. Howev er, cluster analysis that included nine variables formed groups that s uggested contrast both between centers of domestication and between wi ld and cultivated types. Cluster analysis performed for Mexico and Per u identified two major groups that corresponded to wild and landraces within those countries. We conclude that wild populations and landrace s differ in characteristics related to leaf photosynthesis, at least i n Fern and Mexico. Wild Peruvian populations had higher CER than landr aces. Wild Andean and Mesoamerican populations were not different in C ER; this is a very interesting observation that suggests that during d omestication a decrease in CER occurred in Andean landraces.