Using thermoluminescence, PAM-fluorometry, and electron paramagnetic resonance (EPR) for assaying electron transport processes in chloroplasts in situ, we have compared photosynthetic characteristics in Tradescantia fluminensis leaves grown under low light (LL, 50–125 µmol photons m⁻² s⁻¹) or high light (HL, 875–1000 µmol photons m⁻² s⁻¹) condition. We found differences in the thermoluminescence (TL) spectra of LL- and HL-acclimated leaves. The LL and HL leaves show different proportions of the Q (~ 0 °C) and B (~ 25–30 °C) bands in their TL spectra; the ratios of the “light sums” of the Q and B bands being S_Q/S_B ≈ 1/1 (LL) and S_Q/S_B ≈ 1/3 (HL). This suggests the existence of different redox states of electron carriers on the acceptor side of PSII in LL and HL leaves, which may be affected, in particular, by different capacities of their photo-reducible PQ pools. Enhanced content of PQ in chloroplasts of LL leaves may be the reason for an efficient performance of photosynthesis at low irradiance. Kinetic studies of slow induction of Chl a fluorescence and measurements of P₇₀₀ photooxidation by EPR demonstrate that HL leaves have faster (about 2 times) response to switching on actinic light as compared to LL leaves grown at moderate irradiation. HL leaves also show higher non-photochemical quenching (NPQ) of Chl a fluorescence. These properties of HL leaves (faster response to light and generation of enhanced NPQ) reflect the flexibility of their photosynthetic apparatus, providing sustainability and rapid response to fluctuations of environmental light intensity and solar stress resistance. Analysis of time-courses of the EPR signals of \({\text{P}}_{700}^{ + }\) induced by far-red (λ_max = 707 nm), exciting predominantly PSI, and white light, exciting both PSI and PSII, suggests that there is a contribution of cyclic electron flow around PSI to electron flow through PSI in HL leaves. The data obtained are discussed in terms of photosynthetic apparatus sustainability of HL and LL leaves under variable irradiation conditions.

使用热释，PAM-荧光，和电子顺磁共振（EPR）在原位叶绿体测定电子传递过程中，我们比较了在光合特性紫露fluminensis低光（LL下生长的叶子，50-125微摩尔光子中号^-2小号^{- 1} ) 或高光 (HL, 875–1000 µmol 光子 m ^-2 s ^-1 ) 条件。我们发现 LL 和 HL 驯化的叶子的热释光 (TL) 光谱存在差异。LL 和 HL 叶在其 TL 光谱中显示出 Q (~ 0 °C) 和 B (~ 25–30 °C) 波段的不同比例；Q 和 B 波段的“光和”之比为S _Q / S _B ≈ 1/1 (LL) 和S _Q / S _B ≈ 1/3 (HL)。这表明在 LL 和 HL 叶中 PSII 的受体侧存在不同的电子载流子氧化还原状态，这可能特别受到其光还原 PQ 池不同容量的影响。LL 叶片叶绿体中 PQ 含量的增加可能是在低辐照度下光合作用有效进行的原因。缓慢诱导 Chl a荧光的动力学研究和EPR对 P ₇₀₀光氧化的测量表明，与在中等照射下生长的 LL 叶子相比，HL 叶子对打开光化光具有更快（约 2 倍）的响应。HL 叶还显示出更高的 Chl a非光化学淬灭 (NPQ)荧光。HL 叶的这些特性（对光的更快响应和增强 NPQ 的产生）反映了其光合作用装置的灵活性，提供可持续性和对环境光强度和太阳应力抗性波动的快速响应。由远红光（λ _max = 707 nm）、主要激发 PSI 和白光引起的\({\text{P}}_{700}^{ + }\)的 EPR 信号的时间过程分析， PSI 和 PSII 都令人兴奋，表明 PSI 周围的循环电子流对 HL 叶中通过 PSI 的电子流有贡献。获得的数据在可变辐照条件下根据 HL 和 LL 叶的光合装置可持续性进行了讨论。