论文部分内容阅读
以加杨(Populus×canadensis)扦插苗为研究对象,进行不同程度的控水处理,并将其分为对照组、中度胁迫组和重度胁迫组。通过研究不同土壤水分条件造成的木质部结构特征、水力特征、生理特征的变化,以及与栓塞脆弱性的关系,探究加杨水力学与生理特性对不同土壤水分条件的响应,为树木适应干旱环境的生理生态特性提供基础理论依据。结果表明:三组加杨的枝条水势(P_(50))大小为对照组>中度胁迫组>重度胁迫组,加杨通过栓塞脆弱性的变化对不同土壤水分条件表现出一定的响应性;导管直径、导水率、日平均净光合速率均随着土壤水分含量的降低而减小;而栓塞程度则随着土壤水分胁迫的增强而增大。回归分析表明导管直径、导水率、日平均净光合速率与P_(50)之间呈正相关(R~2分别为0.615、0.677和0.547);而栓塞程度与P_(50)之间呈负相关(R~2=0.597)。因此,加杨的木质部导管直径、水力特征和生理指标会随土壤水分条件的不同而产生相应变化,从而影响其栓塞脆弱性,进而对不同的土壤水分条件表现出一定的响应。
Populus × canadensis cuttings as the research object, different degrees of water control treatment, and divided into control group, moderate stress group and severe stress group. By studying the structural characteristics, hydraulic characteristics, physiological characteristics and the relationship with the fragility of xylem caused by different soil moisture conditions, this paper explores the response of the hydraulic and physiological characteristics of poplar to different soil moisture conditions, and provides a theoretical basis for tree adaptation to arid environments Physiological and ecological characteristics provide the basic theoretical basis. The results showed that the water potential (P_ (50)) of Populus tomentosa was dominated by the control group> moderate stress group> severe stress group. Populus euphratica showed some response to different soil moisture conditions through the change of plug vulnerability. Catheter diameter, water conductivity and daily average net photosynthetic rate all decreased with the decrease of soil water content, while the embolism degree increased with the increase of soil water stress. Regression analysis showed that there was a positive correlation between catheter diameter, water conductivity and daily average net photosynthetic rate and P_ (50) (R ~ 2 = 0.615, 0.677 and 0.547, respectively); while the embolization degree was negatively correlated with P_ (50) (R ~ 2 = 0.597). Therefore, the diameter, hydraulic characteristics and physiological indexes of the xylem in Populus canyon change with the different soil moisture conditions, which will affect the fragility of the embolism and thus respond to different soil moisture conditions.