Effects of phosphate deficiency on the growth and acid phosphatase activity of Larix gmelini seedlings

In contrast with the P-adequate solution, the seedlings of Larix gmelini were cultured in the P-deficient solution, and the effects of phosphate(P) deficiency on the growth state, P absorption and the acid phosphatase activity(APA) of the roots were studied. The results revealed that the net increments of the dry weight of the seedlings were all obviously lower during the P deficiency than they were in the control (P＜0.05). The net increments of the dry weight during P deficiency were only 20.5%-26.3% of those of the control. On the contrary, the ratio of roots to shoot (R/S) increased remarkably under the condition of P deficiency compared with the control(P＜0.05), which may be an adapting mechanism in morphology to increase P uptake from the outer environment. The P concentrations in leaves and average P contents in one seedling decreased obviously during P deficiency in comparison with the control (P＜0.05). The average P content in one seedling was only 35.38%-54.25% of the control. The APA in root tissues and those secreted by the roots all increased under P deficiency, which were 1.06-1.32 times and 1.81-2.10 times of those of the control. The increase of APA may be one of the physiological and biochemical mechanisms, by which the L. gmelini seedlings adapt to the P deficiency.