氮对苹果幼树水分利用效率的影响

以２年生盆栽新红星／平邑甜茶苹果树为试材，初步探讨了土壤不同水分状况下氮肥对植株水分利用效率（ＷＵＥ）及有关参数的影响，结果表明，充足供水时，随施Ｎ量的增加，植株ＷＵＥ降低，施Ｎ导致气孔导率（Ｇｓ）增大，对蒸腾（Ｔｒ）的提高幅度大于光合（Ｐｎ）；供水不足时，施Ｎ植株的ＷＵＥ明显高于对照，不同施Ｎ水平的ＷＵＥ表现为：高Ｎ〉中Ｎ〉低Ｎ，ＷＵＥ改善是由于叶肉羧化能力提高，导致光合增强。

Effect of nitrogen on water use efficiency of apple tree

This paper studied the effect of nitrogen fertilizer on water use efficiency(WUE) and relevant parameters of two years old potted apple trees(Starkrimson/ Malus hupenensis) under different soil moisture condition.The results showed that under adequate soil moisture,WUE was decreased with increasing application of nitrogen fertilizer.Nitrogen fertilizer application resulted in an increase of stomatal conductane.Consequently,the transpiration rate was increased more than photosynthetic rate did.Under soil drought,the WUE of plants applied with nitrogen fertilizer was apparently higher than that of control.The WUE value was in the order of high N>medium N>low N.The improvement of WUE was due to the increase of mesophyll capacity,which led to the promotion of photosynthesis.