INFLUENCE OF WHOLE-PLANT NET CALCIUM INFLUX AND PARTITIONING ON CALCIUM-CONCENTRATION IN SNAP BEAN PODS

Snap beans (Phaseolus vulgaris L.) are a food source that can contribu te to dietary Ca requirements in humans. Factors which might enhance t he concentration of Ca in snap bean pods have been investigated by mea suring whole-plant net Ca influx, whole-plant Ca partitioning, and var ious growth parameters in two snap bean cultivars-Hystyle and Lahrador -that differ in pod Ca concentration. Plants were grown hydroponically under controlled environmental conditions while being provided adequa te quantities of Ca. The concentration of Ca in pods (dry weight basis ) was 52% higher in 'Hystyle', relative to 'Labrador', but net Ca infl ux throughout crop development or total plant Ca content at three stag es of development were similar in both cultivars, demonstrating that p od Ca concentration differences were not due to differences in total p lant Ca influx. However,'Hystyle' partitioned more total plant Ca to p ods, relative to 'Labrador'. Calcium flux analysis also revealed that daily rates of whole-plant net Ca influx gradually declined throughout the period of pod growth in both cultivars; this decline was not rela ted to whole-plant water influx. These results suggest that enhancemen ts in whole-plant net Ca influx during pod growth and/or enhancements in the xylem transport of absorbed Ca to developing pods could increas e the Ca concentration of snap bean pods.