Variation in Characters Related to Leaf Photosynthesis in Wild Bean Populations

Abstract

Leaf characters related to photosynthesis in wild bean (Phaseolus vulgaris L.) populations were surveyed to identify genetically useful traits. Fifty wild bean accessions collected from Mexico to Argentina were evaluated at two contrasting field locations. Canonical analysis distinguished four groups of accessions, corresponding to collection sites in Mexico, Guatemala, Peru, and Argentina. Mexican accessions had high photosynthetic rates, low soluble protein contents, and the highest instantaneous photosynthetic nitrogen‐use efficiency (PSNUE). Guatemalan accessions had low photosynthetic rates, low N content, and low PSNUE. Peruvian accessions had high photosynthetic rates, few stomates, high N, high soluble protein, high chlorophyll content, and high PSNUE. Argentinian accessions had low photosynthetic rates, few adaxial stomates, low N content, and low PSNUE. It is proposed that palisade cell size influences leaf photosynthesis by affecting specific leaf weight and therefore N content per unit leaf area. Significant variation within and between origins was observed for adaxial stomatal density. Differences in PSNUE, adaxial stomatal density, and palisade cell volume between individual accessions varied by a factor of 3, 5, and 3.5, respectively. We conclude that genetic variation for leaf photosynthetic characters exists in wild bean germplasm.