低磷胁迫对落叶松幼苗生长及根系酸性磷酸酶活性的影响

以磷充足的完全营养液为对照，研究了低磷胁迫对落叶松幼苗生长、磷吸收及根系酸性磷酸酶活性（APA）的影响.结果表明:低磷胁迫下幼苗的平均单株干重净增量较对照显著降低（P＜0.05），仅为对照的20.5%～26.3%，而苗木的根冠比（R/S）较对照明显增加，可能是落叶松幼苗在低磷胁迫时为增加磷吸收而在形态上主动采取的一种适应性机制.低磷胁迫下苗木叶磷浓度与单株苗木磷含量均较对照显著降低（P＜0.05），单株苗木磷含量为对照的35.38%～54.25%.低磷胁迫下，幼苗根组织内酸性磷酸酶活性与根系分泌的酸性磷酸酶活性均表现出增加，分别为对照的1.06～1.32倍和1.81～2.10倍.根系分泌的酸性磷酸酶活性的增高，可能是落叶松幼苗适应磷胁迫的生理机制之一. 

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.