Translocation of Calcium in the Bean Plant.

Open Access
Publisher Website
Google Scholar
Abstract
Ca from the cotyledons was used by the plant in the early establishment of the root, hypocotyl, and primary leaves, but an external supply was necessary for the subsequent growth of the apical meristem and the trifoliate leaf system. The greatest accumulation of Ca occurred in those parts where transpiration had ensued longest, i.e., the oldest, or primary leaves and in decreasing order: the trifoliate leaves, the stems, and the roots. Little Ca was re-exported following the initial deposition by the transpiration stream. Export of foliarly applied Ca via the phloem was small, i.e., only 1/100 that of P under conditions of maximum transport of each, and was not stimulated by a variety of leaf treatments or nutritional conditions. Xylem export, however, occurred following diethyl-ether treatment, or could be induced during dehydration by applying NaCl in the foliar spray or by treating the plant with triiodobenzoic acid. One facet of the data indicated that the apparent immobility of Ca in the phloem was due more to its failure to cross the border parenchyma into the phloem rather than to its immobility in the phloem itself.