Enhancement of root respiration and photosynthesis in Quercus serrata Thunb. seedlings by long-term aluminum treatment.

In this article, we discuss the effects of long-term (17 months) aluminum (Al) treatment on the growth, root respiration rate, nutrient uptake rate, and photosynthetic activity of two-year-old Quercus serrata Thunb. seedlings. The seedlings were cultivated by supplying a nutrient solution with or without Al twice a week for 17 months in siliceous sand. After 5- and 17-month treatments, growth, root respiration rate, photosynthetic activity, and the concentration of minerals in the roots and leaves were measured. Al treatment for 5 and 17 months markedly enhanced the growth and photosynthetic activity, and Al treatment for 17 months stimulated the root respiration rate. Although Al treatment for 17 months significantly decreased the Ca, Mg, and P concentrations in leaves, this decrease did not cause deficiency symptoms because of significant increases in shoot biomass and photosynthetic activity. The results of this study reveal that an increase in photosynthetic activity supports growth enhancement induced by Al treatment in Q. serrata seedlings, and suggest that Al may act as a trigger in activating some metabolic functions that can induce growth.