Effects of soil pH on the uptake of Al, F and other elements by tea plants

Soil extractable Al, F and Zn concentrations decreased whereas extractable Ca, Cu, K, Mg, Na and P concentrations increased when the soil pH was raised from 3 to 6. These trends led to a decrease in growth of tea seedlings as determined by measurements of relative dry weight gain (RDW), relative leaf number gain (RLN) and relative leaf area gain (RLA). Tea seedlings of both 'large-leafed' and 'small-leafed' varieties grown in soils at pH3 and 3.5 were the tallest and healthiest, while those at pH 6 died after 3 months. The large-leafed variety showed higher growth rates than the small-leafed variety. The highest (p < 0.05) amounts of Al and F, 4225 and 430mg kg^-1 respectively, were found in seedlings under pH 3.5 treatment. When Al and F concentrations in seedlings increased, elements such as Ca, Mg, Na and Zn gently decreased (p < 0.05) whereas P increased. K and Cu were not affected. The results indicated that soil pH values higher than 4 reduced Al and F concentrations in tea plants. Copyright © 2001 Society of Chemical Industry.