Physiological studies on yield and adaptation in Phaseolus vulgaris L

Common beans (Phaseolus vulgaris L.) are an important world crop with a relatively low productivity in most cropping systems. Physiological factors influencing yield are discussed in this paper with respect to field research in the tropics. The comparative earliness of the majority of the germplasm is closely associated with suboptimal canopy development which leads to lower yield potentials. Leaf area development is dependant on the basic nodal structure as is the potential sink. Increases in nodal structure led to increases in both source and sink and consequently yield. The species is comparable to soybeans in terms of various efficiency parameters (yield per unit leaf area duration, harvest index and yield per day of growth cycle) and differences in crop growth rate are proportional to differences in leaf area. Water stress tolerance, and specific adaptation to temperature extremes have been identified in the species while the results of photoperiod response evaluations appear to have future application in predicting phenological response