Effects of low pH and aluminum on root morphology of Japanese red cedar saplings
The effects of low pH or excess Al on the root morphology and nutritional status of Japanese red cedar (Cryptomeria japonica D. Don) saplings were separately examined using glass beads as a medium. We also compared the effects of pH or Al determined by the glass-beads method with those determined by soil-acidification treatment using brown forest soil. An increased number of branching roots, reduced root length and decreased concentrations of Ca and Mg in the white roots were the common symptoms induced by low pH and excess Al. Browning and reduction of K were specific symptoms in white roots subjected to low-pH treatment. The effects of excess Al were characterized by an increase of root diameter and increased concentrations of P and Al in the white roots. Moreover, the effects of Al were very similar to those resulting from exposure to pH 2.0 solution in brown forest soil. These results suggest that the root morphology of the saplings was adversely influenced not by low pH but by excess Al in brown forest soil, indicating that this type of soil may have the potential for producing a decline in the root systems of Japanese red cedar.