Effects of the Absorption of Artificial Acidic Solutions on the Root Systems of Japanese Red Cedar (Cryptomeria japonica D. Don) Cuttings and Saplings

Abstract

The effects of the absorption of artificial acidic solutions only from below-ground parts on root systems were examined for 60 days in summer and 72 days in fall using cuttings and saplings of Japanese red cedar (Cryptomeria japonica D. Don). Cuttings and saplings absorbed the solutions through the potted soils from the reservoir of an autoirrigator and/or a simplified-autoirrigator. Nitric acid solutions of pH 2.0, 4.0 and 6.0 and distilled water (control) were used in summer, mixtures of H2SO4 and HNO3 solutions of pH 2.0, 3.0 and 4.0, HNO3 solution of pH 3.0, H2SO4 solution of pH 3.0 and distilled water (control) were used in fall. Although no detrimental effects of acidic solutions on saplings were observed, the rooting rate of cuttings treated at pH 2.0 in summer was significantly lower than that of the control. Root lengths and root dry weight per cutting at pH 2.0 in summer and fall were smaller than those of the control, and the difference in fall was significant. The present study revealed that the acidic treatment only from below-ground parts had detrimental effects on the root systems of cuttings, suggesting the importance of quantification of the effects on below-ground parts, as well as on above-ground parts, to evaluate the effects of acidic precipitation on trees.