种植年限对黄土丘陵半干旱区山地枣树蒸腾的影响

Effect of Planting Years on Jujube Transpiration in Semi-arid Hilly Areas of Loess Plateau

为了研究山地成年枣树的蒸腾特征以及不同种植年限枣树蒸腾耗水的差异性,运用TDP液流监测系统对山地枣树的蒸腾进行了连续3年的动态监测。通过分析发现：枣树蒸腾日内变化呈单峰变化趋势,而且随着生育期变化呈窄峰-宽峰-窄峰变化。水汽压亏缺（VPD）和光合有效辐射量（PAR）对枣树的蒸腾存在明显的时滞现象和阈值特征,蒸腾对VPD和PAR响应的上限阈值分别为3.5 k Pa和1 000-1 200μmol/（m^2·s）。枣树全生育期逐日蒸腾呈现明显的单峰现象,夜间蒸腾约占全日蒸腾的5%-33%。2012—2014年不同树龄枣树蒸腾量由小到大依次为3 a、5 a、12 a,不同树龄枣树蒸腾耗水之间存在极显著的差异性（p0.01）,而且年际之间的蒸腾波动变化规律不同。由于采取了树体修剪调控措施,12 a生成年枣树年际之间蒸腾差异并不显著（p〉0.05）,各年耗水量基本稳定在293-334 mm之间。由此可见,通过控制树体规模可以调控树体的水分消耗。

In order to study the transpiration characteristics of matured jujube tree and their transpiration difference of different tree-ages,the transpiration of jujube tree were monitored continuously for three years with TDP sap flow monitoring system. The results indicated that the change of daily jujube transpiration showed a single peak trend,and the trend of narrow peak-wide peak-narrow peak appeared with the change of growth periods. Time-lag phenomenon and threshold existed distinctly in jujube transpiration influenced by VPD and PAR. The upper thresholds of VPD and PAR responding to the transpiration were 3. 5 k Pa and 1 000 - 1 200 μmol /（ m^2·s）. Daily jujube transpiration showed a single peak trend obviously during the whole growth period,the proportion of nighttime transpiration was about5% - 33% of the full-day transpiration. The order of jujube transpiration from large to small was 3 a,5 a and 12 a during 2012—2014. The significant differences were found between transpiration（ p〈0. 01）,and the interannual variations（ Cv） of transpiration were different. The transpirations of 12 a jujube were not significantly different among years（ p〉0. 05）,annual water consumption was basically stable at 293- 334 mm. Thus,the jujube transpiration scale gradually expanded with the increase of ages,but it could remain stable relatively by taking reasonable pruning measures.