AN EXPERIMENTAL-STUDY OF CALCIUM ACQUISITION AND ITS EFFECTS ON THE CALCIFUGE MOSS PLEUROZIUM-SCHREBERI

In a field experiment to investigate the sources and effects on growth of Ca in the calcifuge moss Pleurozium schreberi, significant quantities of Ca reached the growing shoot apices from a CaCO3 layer placed on the mineral soil surface Top applications of 0.5 and 5 mol m-3 CaCl2 raised the exchangeable and intracellular Ca concentrations and displaced natural exchangeable K and Mg The 5 mol m-3 CaCl2 treatment also caused a significant reduction in intracellular Mg indicating that Mg uptake is dependent on an initial exchange step No growth differences were noted between treatments, possibly because ionic changes had not reached a detrimental level within the 28 weeks of the experiment in a second experiment, shoot apices of Pleurozium schreberi, Pseudoscleropodium purum and Calliergon cuspidatum were grown on nylon gauze under intermittent distilled-water mist At weekly intervals the shoots were saturated with CaCl2 solutions providing factorial combinations of Ca and pH Growth of C cuspidatum and P purum from chalk soil was reduced at high (0.01) Ca concentration whereas Pleurozium schreberi and Pseudoscleropodium purum from acidic clay were unaffected The pH treatments did not significantly affect moss growth Initial tissue levels of K and Mg were lower in the mosses from chalk and it is suggested that the CaCl2 treatments caused nutrient deficiencies in these plants Mosses from acidic soil contained less exchangeable Ca than the chalk plants and grew poorly in the absence of CaCl2, perhaps due to the development of Ca deficiency © 1990 Annals of Botany Company.