Mobilization of Minerals to Developing Seeds of Legumes

Publisher Website
Google Scholar
Abstract
The mineral nutrition of fruiting plants of Pisum sativum L., Lupinus albus L. and Lupinus angustifolius L. is examined in sand cultures supplying adequate and balanced amounts of essential nutrients. Changes in content of specific minerals in leaves, pods, seed coat, and embryo are described. P, N and Zn tend to increase precociously in an organ relative to dry matter accumulation, other elements more or less parallel with (K, Mn, Cu, Mg and Fe) or significantly behind (Ca and Na) dry weight increase. Some 60–90 per cent of the N, P and K is lost from the leaf, pod and seed coat during senescence, versus 20–60 per cent of the Mg, Zn, Mn, Fe and Cu and less than 20 per cent of the Na and Ca. Mobilization returns from pods are estimated to provide 4–39 per cent of the seeds' accumulations of specific minerals, compared with 4–27 per cent for testa transfer to the embryo. Endosperm minerals are of only minor significance in embryo nutrition. Comparisons of the mineral balance of plant parts of Lupinus spp. with that of stem xylem sap and fruit tip phloem sap support the view that leaves and pod are principal recipients of xylem-borne minerals and that export from these organs via phloem is the major source of minerals to the seeds. Endosperm and embryo differ substantially in mineral compostition from phloem sap, suggesting that selective uptake occurs from the translocation stream during seed development. Considerable differences are observed between species in mineral composition of plant organs and in the effectiveness of transfer of specific minerals to the seeds Differences between species relate principally to Ca, Na and certain trace elements.