不同修剪措施对薄壳山核桃幼树光合特性的影响

【目的】探索不同修剪措施对薄壳山核桃光合特性的影响,为选择合理的整形修剪技术以及栽培优质高产的薄壳山核桃提供科学依据。【方法】以5年生薄壳山核桃幼树为研究对象,采用环割(T1)、环剥(T2)和摘心(T3)3种修剪措施处理当年生枝条,再对其枝条进行光合作用的测定。【结果】3种修剪措施处理下的光合参数及其日变化曲线、光响应参数(包括表观量子效率(A_QY)、光补偿点(L_CP)、最大净光合速率(P_n,max)和光饱和点(L_SP)、暗呼吸速率(R_d)均有较大差异。3个处理的净光合速率(P_n)、蒸腾速率(T_r)和气孔导度(G_s)日变化整体呈现相似的趋势,日平均大小均为T3>T1>T2,而胞间CO₂浓度呈现相反的日变化。T3处理的P_n,max值、A_QY值最高,而L_CP值显著低于其他处理,L_SP和R_d值相对较低,说明T3处理的薄壳山核桃幼树叶片光合能力最强,对光的适应范围广。【结论】在薄壳山核桃开花初期进行摘心处理,能有效提高叶片的光合能力,而环剥、环割则降低其光合能力。

Effects of different pruning measures on the photosynthetic characteristics of pecan seedlings

Objective]The present study investigated efficient pruning measures in pecan(Carya illinoinensis), in order to provide a theoretical basis for cultivating a high-yield. Method]Branches of 5-year-old Carya illinoinensis seedlings were treated with scoring (T1), girdling (T2) or topping (T3) to study the differences between photosynthetic charac-teristics in the three treatments. Results]Photosynthetic parameters and diurnal variation curves and light response pa-rameters (apparent quantum yield (AQY ), light compensation ( LCP ), net photosynthetic rate ( Pn ), light saturation point (LSP ) and dark respiration rate (Rd )) were different among treatments. Net photosynthetic rate (Pn ), transpira-tion rate (Tr ) and stomatal conductance (Gs ) under the three treatments showed similar trends. The average size was T3 >T1 > T2, and the diurnal difference in intercellular CO2 concentration was opposite (T2 > T1 > T3). The maximum net photosynthetic rate (Pn ,max ) and AQY of different treatments were the highest, while the LCP was significantly lower, in T3 compared to the other treatments. Additionally, LSP and Rd were relatively low in T3. This showed that the pecan seedlings grafted with T3 treatment had the strongest photosynthetic capacity and better light adaptation. Conclusion]Topping during the early flowering stage of pecan can effectively improve the photosynthetic capacity of leaves, while gir-dling and scoring can decrease the photosynthetic capacity.