渭北旱原小叶杨苗期的施肥效应

对小叶杨采用盆插土培法辅以田间育苗施肥实验.结果表明:在渭北旱原土壤条件下,N、P、K三要素对于培育小叶杨壮苗都是必不可少的,N素的施用效果最好,凡不施用氮肥的处理,其苗木高生长量、叶面积和干物质量显著降低,且封顶早生长期短,单施氮肥或配合施用氮肥的各个处理则相反,都能有效地提高苗高生长量、叶面积和干物质量,延长了苗木的生长期,并且有避免单施磷、钾所引起蒸腾强度大、耗水多的良好作用;磷肥的施用效果仅次于氮,居第2位,但是磷在小叶杨苗木的径生长中,却起着主导作用;氮、磷、钾或氮、磷配合施用效果为最好,因施用钾肥对小叶杨苗木影响不明显,但它与氮、磷配合施用却显示出了积极的效果.

Fertilization Effect on Populus simonnii Carr in Weibei Loess Plateau in Its Seedling Stage

The experiment of fertilizing Populus simonnii Carr seedlings indicates N,P and K are necessary for cultivating strong Populus simonnii Carr seedlings on Weibei Loess Plateau.The best fertilization effect is from N fertilizer.Either N fertilizer or mixed with other fertilizers can effectively increase seedling height growth,leaf area and dry matter,prolong seedling developing time,and avoid high transpiration and water wasting resulted from only applying P or K fertilizers.The better fertilization effect is from P fertilizer.It plays a dominant role in promoting Populus simonnii Carr seedling diameter growth.The effect comes best with P mixed with N or N and K.Only with K fertilizer the fertilization effect is not obvious.But it is good when K mixed with P and N.