【目的】探索不同砧木类型薄壳山核桃嫁接苗光合及荧光特性差异,为选育优良砧木、改进栽培管理方式提供科学依据。【方法】以薄壳山核桃‘Elliott’、‘Sauber’和‘Podsednik’实生苗作砧木,嫁接品种‘Pawnee’为接穗,研究3种不同砧木1年生‘Pawnee’嫁接苗的光合特性和叶绿素荧光诱导动力学特性。【结果】‘Elliott’嫁接苗(砧木‘Elliott’,接穗‘Pawnee’)在高光强下的净光合速率(P_n)以及对光照的利用范围高于‘Sauber’嫁接苗(砧木‘Sauber’,接穗‘Pawnee’)和‘Podsednik’嫁接苗(砧木‘Podsednik’,接穗‘Pawnee’);‘Podsednik’嫁接苗的暗呼吸速率(R_d)和光补偿点(L_CP)最大,在弱光下消耗有机物最多;‘Sauber’的表观量子效率(A_QY)最大,利用弱光能力最强;水分利用效率(R_WUE)与净光合速率(P_n)极显著正相关,‘Elliott’嫁接苗的R_WUE最大,生产有机物效率更高。荧光分析表明,‘Sauber’嫁接苗的热耗散最大,用于电子传递的量子产额(φ_Eo)以及反应中心捕获的激子将电子传递到初级醌受体(Q_A)之后受体的概率(ψ_o)最小,‘Podsednik’嫁接苗的质体醌大小(S_m)、Q_A被还原次数(N)和质体醌还原速率[S_m/t(F_m)]最高,电子传递效率最高;‘Elliott’嫁接苗的3项荧光性能指数均为最高,‘Sauber’嫁接苗的最小。【结论】‘Elliott’嫁接苗具有更好的光合能力及水分利用效率,对环境的适应性更好,‘Podsednik’嫁接苗的光反应能力更强,‘Sauber’嫁接苗光合能力较弱。

【Objective】 This study aimed to explore the differences in photosynthetic and fluorescence characteristics of pecan (Carya illinoensis) grafting plants grafted on different rootstocks, providing a scientific basis for breeding excellent rootstocks and improving cultivation management methods. 【Method】Pecan cultivars ‘Elliott’, ‘Sauber’ and ‘Podsednik’ were used as rootstocks and grafted using a ‘Pawnee’ scion. Next, the photosynthetic characteristics and chlorophyll fluorescence induction kinetics parameters of grafting seedlings were studied. 【Result】The net photosynthetic rate ( P_n) and use of light of ‘Elliott’ (rootstock: ‘Elliott’; scion: ‘Pawnee’) were higher than those of ‘Sauber’ (rootstock: ‘Sauber’; scion: ‘Pawnee’) and ‘Podsednik’ (rootstock: ‘Podsednik’; scion: ‘Pawnee’). ‘Podsednik’ showed the highest dark respiration rate ( R_d) and light compensation point (L_CP), which suggests higher consumption of organic matter under low light. ‘Sauber’ exhibited a greater ability to use low light owing to its higher apparent quantum efficiency ( A_QY). Water use efficiency (R_WUE) and P_n were significantly positively correlated. ‘Elliott’ showed the highest R_WUE, which is conducive to organic matter production. Fluorescence analysis indicated that ‘Sauber’ had the highest heat dissipation rate and the lowest lectron transport capacity, whereas ‘Podsednik’ had the biggest normalized total complementary area above the O-I-J-P phase ( S_m), the maximum number of primary quinone acceptor (Q_A) reduction events between time 0 and t(F_m) (N) and the highest reduction rate of plastoquinone [S_m/t(F_m)], leading to more efficient electron transfer. The highest and lowest performance index values were found in ‘Elliott’ and ‘Sauber’, respectively. 【Conclusion】‘Elliott’ grafting seedling exhibited the highest photosynthetic capacity and water use efficiency, whereas ‘Sauber’ grafting seedling had the weakest performance in photosynthesis. ‘Elliott’ grafting seedling showed a greater adaptability to the environment, and ‘Podsednik’ grafting seedling had a higher photoreactive capacity.