Differences in mobility of calcium applied to the aboveground parts of broad bean plants (Vicia faba L.)

The mobility of Ca-45 applied to several of the aboveground parts of the broad bean plant (Vicia faba L.) was investigated to determine the effect of foliar application of calcium (Ca). Calcium applied to the top or the underside surface of a leaf scarcely moved from the leaf. A small amount of Ca applied to a pod moved to the inner seeds, but the majority remained on the pod wall. Calcium applied to the stem was the most mobile. Most of the Ca applied to the axillary side of the stem moved to the leaves and pod on the applied nodes. By contrast, more of the Ca applied to the side opposite the axillary side of the stem moved to the upper nodes. Thus, Ca solution should be sprayed onto the stem rather than the leaves for effective foliar application of Ca.