Effects of acidity of the water culture solution on uptake of nutrients by the root of Japanese cedar (Cryptomeria japonica) and Japanese cypress (Chamaecyparis obtusa)

The condition around coniferous trees in the soil is becoming gradually acidic when acid rain falls continuously. Nutrient uptake by the roots of coniferous trees could be affected in such environmental change of root zone. The experiments of water culture of coniferous seedlings in modified systems were carried out using (2-and, 3-year-old) of Japanese cedar (Cryptomeria japonica) and, Japanese cypress (Chamaecyparis obtusa) that are the typical Japanese forest trees. Nine major nutrients such as Na+, NH4+, K+, Ca2+, Mg2+, Cl-, NO3-, PO43-, and SO42-, were given in the water culture solution and growth of trees was observed for two years. The aspects of nutrient uptake by these seedlings and the effects of acidity in culture solution were observed. The following results were obtained. 1)Japanese cedar of 50% and Japanese cypress of 30% in tested seedlings could live for two years. 2) All Japanese cedar and cypress that started in the strong acidic condition (pH=3.0) were dead within three months. 3)The minimum pH value in the acidic condition is estimated as 3.2 for these coniferous seedlings, and it means that they can live at least For two years in this condition. 4) The seasonal pattern of the uptake of nitrogen nutrient by Japanese cedar was determined.