Effect of varying solution ratios of Al to Ca and Mg on the uptake of phosphorus byPinus radiata

Abstract

Pinus radiata (D. Don) seedlings were grown in nutrient solutions in which phosphorus levels varied from deficient to adequate. In the first experiment, Al was substituted for Ca over the range 0 to 0.4 meq/l and P was applied at two low levels (1 and 3 μM/l). In the second experiment, Al was substituted for Mg over the range 0 to 0.35 meq/l and P was applied at three higher levels (8, 32 and 129 μM/l). Most seedlings developed P deficiency symptoms at the two lowest levels of P, and there was a significant response to P level terms of height and dry weight of seedlings. In contrast, there were no differences between dry weights of the seedlings growing in the higher P solutions but shoot height increased as solution P increased. Combined data indicated that P at 32.3 μM/l in solution was optimum for growth.