Abstract
This paper describes the interactive effects of aluminum and phosphorus on growth of hydroponically-cultured, two-year-old Quercus acutissima seedlings. A 1/5 Hoagland medium without phosphorous was prepared as a basic medium by the replacement of NH4H2PO4 with (NH4)2SO4. Using this modified medium, culture solutions containing various concentrations of aluminum and phosphorus were prepared by adding NaH2PO4 and Al2(SO4)314-18H2O. The culture solutions were adjusted at pH 4.0. The control solution containing 0.2 mM phosphorous without aluminum was adjusted to pH 5.8. The seedlings were cultured for 7 weeks from September 21 to November 8, 1994. The dry weight of leaves of the seedlings was reduced by the application of 5.4 mM aluminum alone or with 0.02 and 0.2 mM phosphorus. The application of 2.0 mM phosphorus with 5.4 mM aluminum recovered the reduced leaf biomass caused by aluminum. Dry weights of new roots increased in 0.27, 2.7, and 5.4 mM aluminum solutions without phosphorus. The application of 2.0 mM phosphorus to the media containing 0.27 or 2.7 mM aluminum negated the effect of aluminum on root increment. The application of 2.0 mM phosphorous with 5.4 mM aluminum increased root biomass.
