热锻炼对甘蓝幼苗叶片激发能分配的影响

以喜温凉的蔬菜甘蓝为试材，研究了热锻炼与对照甘蓝幼苗叶片光合速率和叶绿素荧光参数对高温胁迫的响应．结果表明，叶片温度在25-35℃之间，热锻炼苗和对照苗叶片叶绿素可变荧光(Ｆv)、光化学猝灭(qP)、非光化学猝灭(qN)、PSⅡ化学效率(ФPSⅡ)没有明显的变化；当叶温高于35℃时。热锻炼苗的Fv、qP和中ФPSⅡ均明显高于对照，37℃时Fv、qP和ФPSⅡ分别比对照高53％、24％和86％；qN较对照低22％，尤其是与光抑制(光破坏)有关的qNs明显降低，以维持较高的高能态猝灭(qNf)耗散过剩激发能。保护PSⅡ反应中心不受破坏。减轻了光抑制，这与热锻炼幼苗叶片在高温下具有较高的光合能力是一致的。

Effect of heat hardening on allocation of excitation energy in Brassica oleracea seedling leaves

In this paper, Brassica oleracea was used to investigate the effect of heat hardening (HH) on its photosynthetic characteristics and chlorophyll fluorescence parameters. No distinct changes were observed in the variable fluorescence (Fv), photochemical quenching coefficient (qP), non-photochemical quenching coefficient (qN), and quantum yield of PS II electron transport (phiPS II) between HH treatment and control when the leaf temperature was 25-35 degrees C. When the leaf temperature was higher than 35 degrees C, there were obvious differences in the levels of Fv, qP, phiPS II and qN between HH treatment and control. For example, at 37 degrees C, the Fv, qP and phiPS II in HH treatment were 53%, 24%, and 86% higher than those in control, respectively, but the qN was 22% lower. The photoinhibitory quenching (qNs) in HH treatment was significantly decreased. The results showed that 'high energy' quenching (qNf) was an important photoprotection mechanism that effectively dissipated the excess excitation energy, protected the PS II reaction center complexes from photodamage, and increased the ability of resisting photoinhibition, which were consistent with high photosynthesis rates.