白桦、落叶松苗木的养分吸收动力学特征1）

摘要

以白桦、落叶松播种苗为试验材料，采用水培养分耗竭法，对两树种苗木根系NO-3、NH＋4、H2 PO-4、K＋吸收动力学进行了研究。结果表明：白桦苗木对NO-3、NH＋4和H2 PO-4的最大吸收速率小于落叶松，对K＋的最大吸收速率大于落叶松。白桦对NH＋4、H2 PO-4、K＋的亲和力大于落叶松，对NO-3的亲和力小于落叶松。白桦喜NO-3-N，落叶松喜NH＋4-N，在两种氮素形态同时存在时，白桦对NO-3的最大吸收速率大于NH＋4，落叶松相反。两树种混交有利于落叶松吸收土壤中的NO-3及白桦吸收土壤中K＋；当土壤中NH＋4和H2 PO-4浓度较低时，有利于白桦吸收，浓度较高时有利于落叶松吸收，养分吸收差异可能对混交林中林木生长产生有益的作用。%The nutrient absorption of N, P and K by roots of birch and larch seedlings was studied by hydroponic culture.Imax of NO-3 , NH+4 and H2 PO-4 of birch seedlings are lower than those of larch, while K+is higher.The Km of NH+4 , H2 PO-4 and K+in birch seedlings are more than those of larch, while NO-3 is less.Birch prefers NO-3-N, while larch prefers NH+4-N. Imax of NO-3of birch is greater than that of NH+4 , for larch it is opposite, when two nitrogen sources exist simultaneously. The different absorption capacity of N, P and K is benefit to uptake NO-3 for larch, while benefit to uptake K+for birch in mixed forests.Birch prefers to uptake nutrient when NH+4 and H2 PO-4 are in low content in the soil, for larch it is opposite. Differences in nutrients uptake can be benefit for the growth of both birch and larch in mixed forests.