With poplar clone (Populus × euramericana cv. ‘ 74/76’ ) as the research object, this paper investigated the variation of stem sap flow, transpiration rate ( Tr ) and leaf water potential ( LWP ) during the growing season ( June to September). The experiment set two experimental sites:one was 4-year-old poplar clone, and the other was 6-year-old.There were 3 treatment levels in each site: the CK(unpruned), P1( 1/3 crown was pruned) and P2 (2/3 crown was pruned). The results showed: 1 ) The flux and velocity were P1 ＞ CK ＞ P2 during dry season(June to August). But, in wet season of September, the flux and velocity were CK ＞ P1 ＞ P2. The Flux and velocity of P1 were almost same between drought or wet months, which indicated that the stem sap flow of poplar was maintained at a certain low level by proper pruning and the capability of counteracting drought observably was increased after the pruning. 2 ) The order of transpiration rate(Tr) and leaf water potential(LWP) was CK ＜ P1 ＜ P2, which suggested that the physiological capability of individual leaf in maintaining water balance was observably improved by pruning.%以欧美107杨为研究对象,从树干液流、蒸腾速率(Tr)以及叶水势(LWP)等杨树水分生理指标角度,探讨修枝处理对这些生理指标在生长季(6-9月)内的影响及其变化规律,并做相应的分析和讨论.试验地Ⅰ以4年生107杨为样木,试验地Ⅱ以6年生107杨为样木.试验地I,Ⅱ均设计3个处理组,每个处理组设有3种处理,即对照处理CK(不修枝)、中度处理P1(修掉树冠高度的1/3)、重度修枝P2(修掉树冠高度的2/3).研究结果表明:1)发生旱情季节(6-8月),液流通量及液流速率呈现Pl>CK>P2的规律;正常月份(9月),液流通量及液流速率呈现出CK>Pl>P2的规律;Pl的液流通量及速率在旱季或正常月份大小基本相同.这表明同正常月份未修枝CK相比,适当修枝(P1)使杨树树干液流始终保持在一定的较低水平,抗旱能力得到一定程度的提高.2)整个生长季内,蒸腾速率(Tr)和叶水势(LWP)都呈现出CK展开▼
