Wang S W, Xing C J, Zhang C F, Guo T, Hao H L, Zhang Z Y, Wang S, Shu J M
College of Forestry and Landscape Architecture, Xinjiang Agricultural University/Key Laboratory of Forestry Ecology and Industry Technology in Arid Region, Education Department of Xinjiang, 311 Nongdadong Road, 830052 Urumqi, Xinjiang, China.
Photosynthetica. 2023 Jan 30;61(1):13-24. doi: 10.32615/ps.2023.003. eCollection 2023.
To clarify the effect of leaf scorch on walnut leaf photosynthesis, photosynthetic parameters were measured in 'Wen185' and 'Xinxin2' symptom trees (WS, XS) and symptomless trees (WH, XH). At the early stage of infection and under the low-grade leaf scorch, WS showed significantly lower net photosynthetic rate ( ), stomatal limitation (L), and higher intercellular CO concentration ( ) than those of WH. However, at the mid to late stage of infection and under the high-grade leaf scorch, WS showed significantly lower , , the maximal quantum yield of PSII photochemistry and higher L, minimal fluorescence yield of the dark-adapted state, nonphotochemical quenching than those of WH, which would occur once 'Xinxin2' was infected. The above results indicated the effect of leaf scorch on walnut leaf photosynthesis was related to the walnut varieties and the duration and severity of the disease. Under the influence of leaf scorch, the decline in photosynthesis of 'Wen185' leaves changed from stomatal to nonstomatal restriction, while 'Xinxin2' leaves showed always nonstomatal restriction.
为阐明叶焦病对核桃叶片光合作用的影响，对‘温185’和‘新新2’的感病症状树（WS、XS）和无症状树（WH、XH）的光合参数进行了测定。在感染初期且叶焦病程度较低时，‘温185’感病症状树（WS）的净光合速率、气孔限制值（L）显著低于无症状树（WH），胞间CO₂浓度（Ci）则显著高于无症状树（WH）。然而，在感染中后期且叶焦病程度较高时，‘温185’感病症状树（WS）的净光合速率、气孔导度、PSII光化学最大量子产量显著低于无症状树（WH），气孔限制值（L）、暗适应态最小荧光产量、非光化学猝灭显著高于无症状树（WH），‘新新2’感病后也出现类似情况。上述结果表明，叶焦病对核桃叶片光合作用的影响与核桃品种以及病害持续时间和严重程度有关。在叶焦病影响下，‘温185’叶片光合作用的下降从气孔限制转变为非气孔限制，而‘新新2’叶片始终表现为非气孔限制。
