Abstract
The growth and photosynthetic responses of 2-year-old seedlings of red pine (Pinus densiflora SIEB. et ZUCC. ) grown in brown forest soil originating from granite acidified by adding H_2SO_4 solution were investigated. The seedlings were grown in a greenhouse for 120 d from May 10 to September 7, 1996. The pH level was reduced, and the concentration of Al in the soil solution increased as the amount of H^+ added as H_2SO_4 solution was increased in the soil. The dry weight growth of the seedlings reduced as the amount of H^+ added to the soil was increased. There was a highly positive correlation between the dry weight growth of the seedlings grown in the acidified soil and the molar (Ca+Mg+K) / Al ratio in the soil solution. The net photosynthetic rate of the seedlings grown in the acidified soil declined as the amount of H^+ in the soil increased. In the seedlings grown in acidified soil, the quailtum yield and carboxylation efficiency of photosynthesis decreased, which suggests that soil acidification induced an inhibition of photochemical reactions of photosynthesis and a reduction in the activity and / or amount of Rubisco.
