| Abstract: | A detailed study of the calcifuge Lupinus Iuteus L. (yellowlupin) has been carried out in an attempt to explain its poorperformance in the presence of high concentrations of rhizosphenccalcium. Plants were grown on two different calcium regimes,1 or 15 mol m– Ca and, after an establishment period,measurements were made of the rate of leaf extension, finallength of the leaflets and the leaf gas exchange. In addition,the distribution of calcium within the leaf tissue was investigated. At 15 mol m–3 Ca, leaflet length at full expansion wasreduced as a consequence of reduced extension rate and a declinein cell wall extensibility. Transpiration in excised leaves,assayed gravimetrically, was significantly reduced in plantsgrown in high calcium. Similar results were also obtained fromgas exchange measurements. Analysis of A/C, curves indicatedthat in plants grown in high Ca] there was a substantial reductionin net assimilation over a range of concentrations of CO2 X-raymicroanalysis revealed that a large amount of cal cium deliveredin the xylem sap is retained in the mesophyll tissue, and mostof that reaching the epidermal tissue is not found in the guardcells but in the cells adjacent to them, which in this speciesare not anatomically distinct as ‘subsidiary’ cells. Key words: Calcium, calcifuge, Lupinus luteus, stomata, leaf growth |
