钾对苹果树水分利用效率及有关参数的影响

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钾对水分利用效率（ＷＵＥ）及有关参数的影响，结果表明，充足供水时，施钾肥植株的气孔导度（Ｇｓ）增大，光合速率（Ｐｎ）和蒸腾速率（Ｔｒ）同时被提高，但Ｔｒ的提高幅度更大，导致了ＷＵＥ的降低；土壤干旱时，钾可明显提高植株的ＷＵＥ，不同处理的ＷＵＥ大小顺序为：高Ｋ〉中Ｋ〉低Ｋ〉ＣＫ，植株施钾肥后，Ｇｓ增大，Ｐｎ被提高，但Ｔｒ却下降，说

EFFECT OF POTASSIUM ON WATER USE EFFICIENCY AND RELEVANT PARAMETERS OF APPLE TREES

2-year-old potted Starkrimson/ M. hupenensis Rehd. apple trees were used as materials in the experiment. Effect of potassium on water use efficiency and relevant parameters of plants under conditions of different soil water status was preliminarily studied. The results showed that under the condition of adequate soil water content,stomatal conductance (Gs), photosynthetic rate (Pn) and transpiration rate (Tr) were all improved for trees applied potassium fertilizer, which resulted in the reduction of WUE because Tr was increased more than that Pn was. However, under the condition of soil drought, WUE of trees applied potassium fertilizer was apparently promoted as compared with contrast ones. WUE of trees with different potassium level was increased in the order: high K> medium K> low K. For treated plants under soil drought, as a result Gs and Pn were enhanced but Tr lowered, the improvement of WUE was due to both the increase of photosynthetic rate and the decrease of transpiration rate.