华山松不同叶龄、部位针叶叶绿素荧光参数的动态变化规律

该文探讨了华山松不同叶龄、不同部位的针叶叶绿素荧光参数的动态变化规律。结果表明:①华山松针叶的PSⅡ最大光能转换效率(Fv/Fm)的日变化呈现明显的先减小后增大的动态规律，在12:00达到最低值；而向阳针叶的非光化学猝灭系数(NPQ)在12:00达到最大值，说明华山松具有在强光条件下通过热耗散作用降低光合机构受光抑制程度和免受光氧化破坏的机制。②华山松阴生叶的各项荧光参数日变化幅度均较小，阴生叶的最大荧光(Fm)、可变荧光(Fv)、Fv/Fm、电子传递效率(Fm/F0)及PSⅡ潜在活性(Fv/F0)均明显高于阳生叶，但阴生叶的NPQ明显低于阳生叶，尤其是幼叶。③针叶叶龄越小，Fv/Fm越低，针叶所受光抑制程度越深，热耗散机制启动得越早、越强。④与阳生叶相比，在不同测定时期阴生叶均具有更高的Fv/F0和Fv/Fm；阴生、阳生针叶荧光参数的变化较叶龄荧光参数的变化更为稳定。 

Dynamic laws of chlorophyll fluorescence parameters in needle leaves of different leaf ages and locations of Pinus armandii

Dynamic laws of chlorophyll fluorescence parameters in needle leaves of different leaf ages and locations of Pinus armandii Franch were studied in this paper. The results are as follows: 1)The daily change of F_v/F_m (maximal photochemical efficiency of PSⅡ in the dark) in needle leaves of P. armandii obviously presented a descending ascending trend，the lowest value was at 12：00 and the NPQ (non photochemical quenching) of sunny needle leaves arrived at the maximum at noon. This shows that P. armandii has the mechanism of declining the degree of photosynthetic inhibition and avoiding the destruction by light catalyzed oxidation through hot dissipation under strong light. 2)The daily change range of every chlorophyll fluorescence parameter in shade needle leaves of P. armandii was small and its values of F_m (maximal fluorescence)，F_v (variable fluorescence)，F_v/F_m，F_m/F₀ (electron transfer rate)，F_v/F₀ (potential activity of PSⅡ) were obviously higher than those in sunny needle leaves and the NPQ of shade leaves was obviously lower than that of sunny leaves，especially young leaves. 3)The smaller needle age was，the lower potential light energy translation efficiency was and the deeper photosynthetic inhibition would be produced，the more early and strong the hot dissipation started. 4)Comparing to sunny needle leaves，shade needle leaves had the higher PSⅡ potential activity and inner light energy translation efficiency. The variation of chlorophyll fluorescence parameters of sunny or shady needle leaves was stabler than that of needle age.