Algae and Higher Plants

Abstract

The complicated pathway followed by water and mineral compounds which enter the plant roots from the soil and are therefrom transported through xylem vessels into the overground parts of plants has attracted the attention of plant physiologists for many years. Nevertheless, much of the mechanism of this efficient system as well as of that of the organic substances supply by the phloem is not yet fully understood, especially the nature of the driving forces involved. On the other hand, a number of useful data characterizing the water and ion uptake at the membrane level have been obtained as can be seen from several reviews and monographs (Blinks, 1955; Arisz, 1956; Epstein, 1956; Laties, 1959a; Russel and Barber, 1960; Fried and Shapiro, 1961; Dainty, 1962; Brower, 1965; Legett, 1968; Schilde, 1968a, Briggs et al., 1961; Steward and Sutcliffe, 1961; Jennings, 1963). The whole of the nutritional requirements of autotrophic organisms like plants is met by the uptake of the inorganic substances, this uptake being subject to various regulations. The aim of this chapter is to describe the present ideas about the transfer of ions and water across the cell membranes, the related bioelectric phenomena, and cell activities behind these processes.