【目的】研究不同水肥管理措施对华北地区杨树主栽品种光合作用、氮代谢关键酶活性及相关指标的影响,为杨树人工林特别是大径材培育高效精准水肥管理体系构建提供理论依据。【方法】以华北沙地11年生欧美杨107(Populus × euramericana ‘Neva’)人工林为研究对象,设置常规沟灌(CK)、滴灌(ND)、控释肥 + 滴灌(CD)、水溶肥 + 滴灌(M1D、M2D)、配方肥+滴灌(F1D、F2D)等7种水肥管理措施,连续测定生长季(7—9月)不同水肥管理措施下杨树叶片光合作用、氮代谢等相关生理生化指标的变化,比较杨树人工林生理生化特征差异,并利用隶属函数分析法综合评价不同水肥管理措施对杨树生理生化指标的影响。【结果】不同水肥管理措施对杨树人工林氮代谢[硝酸还原酶(NR)、谷氨酸合成酶(GOGAT)、谷氨酸脱氢酶(GDH)]、光合作用[核酮糖-1,5-二磷酸羧化/加氧酶(Rubisco)、果糖-1,6-二磷酸酶(FBA)]关键酶活性,以及可溶性糖(soluble sugar,SS)和叶绿素(chlorophyll,Chl)含量有显著影响(P < 0.05),且各指标值随月份变化表现出持续增加趋势;月份和处理间交互作用极显著(P < 0.01),并在9月时各指标数值达到最大。与CK相比,ND处理下叶片NR、GOGAT、GDH、Rubisco、FBA活性和SS含量增加,但总体差异不显著;与ND相比,不同水肥耦合管理措施(CD、M1D、M2D、F1D、F2D)下叶片这些生理生化指标显著提高了13.60%~188.56%;与CD相比,滴灌施肥(M1D、M2D、F1D、F2D)下叶片光合作用和氮代谢关键酶活性及SS含量显著提高了11.22%~68.78%。F1D和F2D处理下,8月和9月的叶片Chl含量显著增加,比M1D和M2D处理提高了31.29%~123.55%。通过隶属函数分析得知,F2D处理对杨树各生理生化指标的影响最大,F1D和M2D的影响次之。【结论】不同水肥管理措施能显著影响华北地区杨树人工林叶片的光合和氮代谢关键酶活性,以及可溶性糖和叶绿素含量,其中滴灌施肥措施的影响最大,显著高于其他措施,中、微量元素的添加有助于显著提高叶绿素含量。采用滴灌施肥技术措施,其中施肥配比为520 g/(株·a)N、169 g/(株·a)P₂O₅、312 g /(株·a)K₂O同时添加5 g/(株·a)中、微量元素(包括Fe、Ca、Mn、Zn)对杨树人工林生理生化特征的影响最大。研究结果可为构建华北沙地及相似生态立地条件区域杨树人工林,特别是大径材的高效培育精准水肥管理体系提供理论和技术参考。

【Objective】This research aims to study the effect of photosynthesis, nitrogen metabolism key enzyme activities and other related indexes of poplar main planting varieties under different water and fertilizer management, and to provide a theoretical basis for the construction of efficient and precise water and fertilizer management system of poplar plantations, especially for the cultivation of large diameter timber.【Method】Taking the 11-year-old Populus × euramericana ‘Neva’ plantation in the sandy area of north China as the research object. Seven water and fertilizer management treatments were set up: conventional furrow irrigation (CK), drip irrigation (ND), controlled-release fertilizer + drip irrigation (CD), and water-soluble fertilizer + drip irrigation (M1D, M2D), formula fertilizer + drip irrigation (F1D, F2D). During the growing season (July to September), continuous monitoring was performed to assess key physiological and biochemical indices associated with photosynthesis and nitrogen metabolism in poplar leaves across the different treatments. Subsequently, we analyzed and compared the physiological and biochemical responses of the plantation under varying management regimes. Finally, a comprehensive evaluation of the effects of different water and fertilizer strategies was conducted using subordinate function analysis.【Result】Different water and fertilizer management on nitrogen metabolism (nitrate reductase (NR), glutamate synthase (GOGAT), Glutamate dehydrogenase (GDH)), photosynthesis (ribulose-1,5-diphosphate carboxylase/oxygenase (Rubisco), fructose-1,6-bisphosphate phosphatase (FBA)) key enzyme activities, soluble sugar (SS) and chlorophyll (Chl) content were significantly affected (P < 0.05), and the values of each index showed a continuous increasing trend with month, and the interaction between month and treatment was highly significant (P < 0.01). Under all water and fertilizer management, the overall trend of each index showed continuous increase with increasing months and reached the maximum value of each index in September. NR, GOGAT, GDH, Rubisco, FBA activity and SS content were increased under ND treatment compared to CK, but the overall difference was not significant; compared with ND these physiological and biochemical indexes were significantly increased by 13.60%-188.56% under different water-fertilizer-coupled management (CD, M1D, M2D, F1D, F2D); compared with CD, drip fertigation (M1D, M2D, F1D, F2D) significantly increased the activities of key enzymes of photosynthesis and nitrogen metabolism and the SS content by 11.22%-68.78%. The Chl content was significantly increased mainly in F1D and F2D in August and September, and was significantly increased by 31.29%-123.55% over M1D and M2D. The analysis of the subordinate function analysis showed that the F2D treatment had the greatest effect on the physiological and biochemical indexes of poplar, followed by F1D and M2D.【Conclusion】Different water and fertilizer management can significantly affect the physiological and biochemical indexes of photosynthesis and nitrogen metabolism enzyme activities in poplar plantation, among which the drip fertigation measures have the greatest impact, significantly higher than other measures, and the addition of medium and trace elements helps to significantly increase the chlorophyll content. Drip fertigation measures were adopted, in which the annual fertilizer ratios were N(520 g per tree), P₂O₅(169 g per tree) K₂O(312 g per tree), and the annual addition of 5 g per tree of trace elements (including Fe, Ca, Mn and Zn) had the greatest impact on the physiological and biochemical characteristics of poplar plantation. The results provide theoretical and technical references for the construction of a precise water and fertilizer management system for efficient cultivation of poplar plantation in sandy areas of north China and similar ecological conditions, especially for large diameter timber.