Analyses
Shoots and roots of plants were dried at 80°C.Total N in plants was analysed by means of theKjeldahl method. Cations were determined afterdry-ashing at 450°C for 20 hrs and solubilizationof the ash in 5M HNO3 using an atomic adsorptionspectrometer (Spectra 220 FS, Varian Co. Australia). The P concentration was measured in the ash so-lution using the vanadate-molybdate method(Gericke and Kurmies 1952). The alkalinity ofshoots and roots was measured with the methodof Jungk (1968). Water-soluble glucose, fructose,and sucrose (extraction at 60°C) were enzymatically analysed using an enzymatic test kit (Fortmeier and Schubert 1995). The root length was measured using the line-intersection method (Tennant 1975). Theresults were statistically evaluated (mean value,standard error of mean) with a one- or two-factoranalysis of variance at the 5% probability level ofsignificance using the software program Statgrafics Plus Version 3 for Windows.