热锻炼对甘蓝幼苗叶片激发能分配的影响

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

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 2 5～ 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光化学效率 (PSⅡ)没有明显的变化 ;当叶温高于 35℃时 ,热锻炼苗的Fv、qP和PSⅡ均明显高于对照 ,37℃时Fv、qP和PSⅡ分别比对照高 5 3%、2 4 %和 86 % ;qN较对照低 2 2 % ,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 .

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(F_v),photochemical quenching coefficient(qP),non-photochemical quenching coefficient(qN),and quantum yield of PSⅡ electron transport(PSⅡ) between HH treatment and control when the leaf temperature was 25～35 ℃.When the leaf temperature was higher than 35℃,there were obvious differences in the levels of F_v,qP,PSⅡ and qN between HH treatment and control.For example,at 37 ℃,the F_v,qP and PSⅡ 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 PSⅡ reaction center complexes from photodamage,and increased the ability of resisting photoinhibition,which were consistent with high photosynthesis rates.