中文摘要：

植物的蒸发率被蒸汽压力赤字(VPD ) 和有气孔的传导力的大小身体上控制。一个有限蒸发的特点在不同环境为许多庄稼种类被报导了，包括玉米(Zea mays L.) 。在限制蒸发的结果在高 VPD 下面评估的这个特点，和罐头潜在地保存土壤水并且因此减少土壤水赤字。然而，蒸发率上的如此的限制从来没在干旱气候的条件下面在玉米被探索过在西北的中国。这研究的目的是在叶和整个植物层次在一个干旱区域在浇得好的条件下面检验地成年的玉米的蒸发率，调查到因此怎么蒸发率在不同空间、时间的规模对周围的 VPD 作出回应。在叶和植物规模的玉米的蒸发率分别地用一个煤气的交换系统和 sapflow 仪器独立地被测量。结果在不同时间空间的规模之中在对 VPD 的玉米的蒸发回答显示出重要变化。当时，二阶段的蒸发回答与 3.5 kPa 的阀值在叶水平被观察在整个植物水平，白天蒸发率断然越过所有测量数据与 VPD 被联系，，是对在叶和整个植物水平的 VPD 的夜间蒸发反应，它没显示出可限定的阀值蒸汽压力赤字，在蒸发上面，率被限制。关于时间的规模，蒸发对在每日的规模的 VPD 很应答，在中等应答一半小时地可伸缩，并且在即时规模最不应答。在即时叶的反应的一个类似的断点(大约 3.0 kPa ) 有气孔的传导力并且时时，到 VPD 的华盖体积传导力也被观察。在每日的规模，最大的华盖体积传导力发生在 VPD 大约 1.7 kPa。通常，到在华盖规模的 VPD 的有气孔的传导力的应答在叶规模是比那低的。这些结果显示在的时间、空间的异质对在干旱气候的条件下面的 VPD 的玉米蒸发回答。这能允许对使用最大的蒸发特点在干旱环境改进玉米干旱忍耐的可能的好处的一个更好的评价，并且允许支撑的植物蒸发的更好的预言为在处于干旱气候的条件的不同时间空间

英文摘要：

The transpiration rate of plant is physically controlled by the magnitude of the vapor pressure deficit（VPD） and stomatal conductance. A limited-transpiration trait has been reported for many crop species in different environments, including Maize（Zea mays L.）. This trait results in restricted transpiration rate under high VPD, and can potentially conserve soil water and thus decrease soil water deficit. However, such a restriction on transpiration rate has never been explored in maize under arid climatic conditions in northwestern China. The objective of this study was to examine the transpiration rate of field-grown maize under well-watered conditions in an arid area at both leaf and whole plant levels, and therefore to investigate how transpiration rate responding to the ambient VPD at different spatial and temporal scales. The transpiration rates of maize at leaf and plant scales were measured independently using a gas exchange system and sapflow instrument, respectively. Results showed significant variations in transpiration responses of maize to VPD among different spatio-temporal scales. A two-phase transpiration response was observed at leaf level with a threshold of 3.5 k Pa while at the whole plant level, the daytime transpiration rate was positively associated with VPD across all measurement data, as was nighttime transpiration response to VPD at both leaf and whole plant level, which showed no definable threshold vapor pressure deficit, above which transpiration rate was restricted. With regard to temporal scale, transpiration was most responsive to VPD at a daily scale, moderately responsive at a half-hourly scale, and least responsive at an instantaneous scale. A similar breakpoint（about 3.0 k Pa） in response of the instantaneous leaf stomatal conductance and hourly canopy bulk conductance to VPD were also observed. At a daily scale, the maximum canopy bulk conductance occurred at a VPD about 1.7 k Pa. Generally, the responsiveness of stomatal conductance to VPD at the canopy scale was l