Stomatal density of pods and leaves were determined for six commercial snap bean cultivars (Phaseolus vulgaris L. `Evergreen', `Hystyle', Labrador', `Tenderlake', `Top Crop', and `Venture') grown at three planting dates, in an attempt to find morphological traits that could be related to cultivar differences in pod Ca concentration. Snap beans were planted three times at ≈1-week intervals beginning 15 June 1995, and harvested 59 to 62 days after planting. Stomatal counts were performed using a microscope linked to a video camera, and Ca concentration determinations were made using atomic absorption spectrophotometry. Calcium concentration and stomatal density of leaf tissue was higher than that of pods. Cultivar differences for pod Ca concentration (P = 0.001) and stomatal density (P = 0.001) were observed although cultivars with higher pod stomatal density did not necessarily result in higher pod Ca concentration. Calcium concentration and stomatal density for leaves did not differ among cultivars. Stomatal density and Ca concentration of pods were positively correlated (R 2 = 0.37), while pod maturity was negatively associated to both pod Ca concentration (R 2 = 0.93), and pod stomatal density (R 2 = 0.99). The effect of planting dates was absent in pod Ca concentration and significant in pod stomatal density.
J.M. Quintana, H.C. Harrison, J.P. Palta, J. Nienhuis, K. Kmiecik, and E. Miglioranza
Xuan Liu and Donald L. Suarez
after planting (DAP) at the vegetative growth stage and at 68 to 72 DAP at pod-filling or pod growth stage. The harvested plants were immediately brought to the laboratory and their root zone up to the stem base washed with tap water and then rinsed with
Michael A. Grusak, Brian W. Stephens, and Donald J. Merhaut
Snap beans (Phaseolus vulgaris L.) are a food source that can contribute to dietary Ca requirements in humans. Factors which might enhance the concentration of Ca in snap bean pods have been investigated by measuring whole-plant net Ca influx, whole-plant Ca partitioning, and various growth parameters in two snap bean cultivars—Hystyle and Labrador—that differ in pod Ca concentration. Plants were grown hydroponically under controlled environmental conditions while being provided adequate quantities of Ca. The concentration of Ca in pods (dry weight basis) was 52% higher in `Hystyle', relative to `Labrador', but net Ca influx throughout crop development or total plant Ca content at three stages of development were similar in both cultivars, demonstrating that pod Ca concentration differences were not due to differences in total plant Ca influx. However, `Hystyle' partitioned more total plant Ca to pods, 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 related to whole-plant water influx. These results suggest that enhancements in whole-plant net Ca influx during pod growth and/or enhancements in the xylem transport of absorbed Ca to developing pods could increase the Ca concentration of snap bean pods.
Wesley Gartner, Paul C. Bethke, Theodore J. Kisha, and James Nienhuis
, are collectively referred to as the pod. Fertilization occurs on the day of anthesis ( Walbot et al., 1972 ). Pod growth begins ≈2 d later ( Carr and Skene, 1961 ) and is supported by sucrose imported from leaves and sucrose supplied by photosynthetic
Caixi Zhang, Kenji Tanabe, Hiroko Tani, Hiromitsu Nakajima, Minori Mori, and Emi Sakuno
3 are the active GAs that induce fruit set and pericarp growth. The concentrations of GA 1 and GA 3 were highest at the time of most rapid pod growth rate (4–7 DAA), but present in trace or undetectable amounts in unpollinated ovaries and in