The Response of Serpentine and Non-Serpentine Agrostis Stolonifera to Magnesium and Calcium

Abstract

Three water culture experiments were carried out with 3 races of A. stolonifera: one from an extreme serpentine site with a very low Ca/Mg ratio in the soil at Kittelfjal in Sweden, one from a less extreme type of serpentine soil on Unst (Scotland), and one from a commercial, presumed non-serpentine source (Denmark). Clonal material was maintained in John Innes compost. There were considerable differences in the initial nutritional status of material used in the 3 experiments and the implications of these are discussed. Evidence was found for a higher Mg-requirement and a higher tolerance of excess Mg in the 2 serpentine races. The race from the extreme serpentine site was more tolerant than that from the less extreme site. Over much of the range of Mg and Ca concentrations used in the culture solutions the serpentine races had a higher concentration of Mg in the roots and shoots and a lower concentration of Ca in the roots. These results point to a difference between A. stolonifera and certain plants of serpentine sites investigated in the USA, which have been found to exclude Mg and to have a particularly active Ca-uptake system. No evidence was found of a greater requirement for Ca in the non-serpentine race. The Ca/Mg ratio in shoot tissue may be higher or lower than that in the roots depending on the Ca/Mg ratio of the external solution.