以2种杨树(毛白杨和速生杨)作为被子植物的代表树种,与4种松树(油松、赤松、白皮松和华山松)进行叶绿素快相荧光光动力学曲线和参数比较,总结2类树种在快相荧光动力学方面的差异。结果显示:与杨树典型的OJIP曲线不同,松树针叶快相荧光动力学曲线上J相的相对荧光强度较低,没有明显的I相,达到P相的速度较快。解析荧光数据得到的荧光参数显示,松树针叶单位激发态面积反应中心的数目(RC/CS。)较少,导致其单位PsⅡ反应中心获得的能量较多(ABS/RC,TR0/RC,ET0/RC,DI0/RC),其单位激发态面积的光反应活性(ABS/CSm,TR0/CSm,ET0/CSm,DI0/CSm)却较低。不过松树的原初光化学活性(Mo)与杨树相差不大,QA(plastoquinoneA)的电子传递活性(ψET)甚至高于杨树。但是,松树的I相相对荧光强度(V1)较高,说明松树从质体醌QB(plastoquinoneB)到PSI的电子传递活性(ψRE)较低。同时,松树的质体醌库(Sm)较小,质体醌的周转次数(N)较少,质体醌库的还原速度(Sm/Tfm)较快,使得松树OJIP曲线(OJIPinductioncurve)上P相出现较早,而I相不明显。最终表现为松树的光反应综合性能指数PIcsm及PSI相对活性(φR0)较低,PsⅡ热耗散量子比率(Kn,F0/Fm)较大。综上所述,单位激发态面积反应中心数目和质体醌库的大小及活性是影响松树光反应活性的2个重要因素,最终影响松树针叶的光合功能。
To further understand light reaction of Pinus (pine) species, the fast chlorophyll fluorescence induction curves and parameters of four species (P. armandii, P. bungeana, P. tabuiaeformis, P. densiflora) were compared with that of two Populus (poplar) species (P. tomentosa, P. euramericana) chosen as representatives of angiosperm trees in this study. The main differences in the fast chlorophyll fluorescence induction kinetics between the two kinds of trees were summarized as the follow. The chlorophyll fluorescence induction curves of the two poplar species were typical OJIP induction curves, while the OJIP induction curves of Pinus species exhibited relatively lower J phase, obscure I phase and earlier P phase. Light reaction characteristics of the four pine species were demonstrated by fluorescence parameters in detail. The RC (RC : PS I1 reaction centre) density per excited cross section (CS) of pine trees leaves was lower than poplar trees, which led to more energy fluxes per RC (ABS/RC, TRo/RC, ETo/RC, DIo/RC) of pine trees. However the primary photochemistry rate (Mo) had no difference between the two kinds of trees. Electron transport efficiency of QA (ψET) in pine trees was even higher than poplar trees. Pine needles had greater values in relative variable fluorescence of I phase ( V1 ) , which indicated that pine trees had lower efficiency of electron transport fluxes from Qs to PSI acceptors (ψRE). Meanwhile, pine trees had smaller plastoquinone pool (Sm) and less turn - over number of QB (N) , along with the faster plastoquinone pool redox rate (Sm/Tfm). These results could be the major cause of obscure I phase and earlier P phase appeared on the OJIP induction curve of pine trees, which further caused smaller values of performance index (Plcsm) , quantum yield of electron transport flux until PSI (φRo) and bigger values of dissipated energy ratio of PS Ⅱ(K, Fo/Fm) in pine trees. The results above suggested that the density of R