摘要： 为探明我国北方烟草移栽期温度和光强等限制因素对烟草光合作用的影响,利用快相叶绿素荧光动力学技术研究了低温((8±2)℃)处理2 h后弱光(200 μmol/(m²·s))和强光(1 000 μmol/(m²·s))处理对烤烟幼苗叶片光化学活性、PSⅡ电子传递以及类囊体膜的聚合状态等方面的影响.结果表明:低温后弱光处理没有明显改变烤烟幼苗叶片的OJIP曲线形态,但低温后强光处理下烤烟幼苗叶片的OJIP曲线形态发生了明显的改变,低温后强光处理下烤烟幼苗叶片的F_v/F_m和PI_ABS均明显降低,即叶片PSⅡ光化学活性降低,而低温后弱光处理则没有明显降低烤烟幼苗叶片的PSⅡ光化学活性,说明低温后强光是引起烤烟幼苗叶片光抑制的重要原因.低温后弱光处理没有改变烤烟幼苗叶片的V_J、M_o和S_m,但低温后强光处理下烤烟幼苗叶片的V_J和M_o明显增加,而S_m没有发生明显变化,说明低温后弱光处理并没有抑制烤烟幼苗叶片PSⅡ受体侧的电子传递能力,但低温后强光处理下烤烟幼苗PSⅡ受体侧电子由Q_A向Q_B传递能力明显降低,并且这直接与低温强光引起Q_B接受电子能力的降低有关,而不是PQ库容量降低间接效应造成的.低温后弱光和强光处理均没有明显改变烤烟幼苗叶片的V_L和V_K,即(8±2)℃的低温处理2 h后弱光和强光处理均没有使烤烟幼苗叶片的OEC活性降低,也没有造成叶绿体类囊体的解离.强光是加剧低温胁迫后烤烟幼苗叶片光抑制的重要诱因,北方春季烤烟移栽期可以考虑阴天移栽或移栽后中午适度遮阴,避免强光伤害.

关键词: 低温, 高光, 烤烟, PSⅡ

Abstract: In order to determine the influence of temperature and light intensity on the photosynthesis of tobacco during transplanting stage in Northern China,in the present study,the impacts of weak light (200 μmol/(m²·s) and strong light (1 000 μmol/(m²·s)) on photochemical activity,PS Ⅱ electron transfer and polymerization of thylakoid membranes of tobacco seedling leaves that had been treated for 2 hours under low temperature ((8±2)℃) were examined according to fast-phase chlorophyll fluorescence kinetics.The results suggested that the weak-light treatment at low temperature didn't apparently change the shape of OJIP curve of tobacco seedling leaves,whereas remarkable changes occurred to the curve shape when the leaves were treated by strong light after low-temperature treatment,as the tobacco seedling leaves were treated by strong light after low-temperature treatment,both F_v/F_m and the PI_ABS declined significantly,in other words,PSⅡ photochemical activity of the leaves was weakened,while it wasn't obviously decreased when the leaves were treated with weak light after low-temperature treatment,this indicated that strong light was an important cause of light inhibition for tobacco seedling leaves.After low-temperature treatment,the V_J,M_o and S_m of tobacco seedling leaves weren't changed when treated by weak light,nevertheless,there presented a significant increase in V_J and M_o when tobacco seedling leaves were treated with strong light after low-temperature treatment,but no prominent changes to S_m,this reflected that the electron transfer ability of tobacco seedling leaves at the receptor side of PSⅡ wasn't inhibited under the situation that they were treated by weak light after low-temperature treatment,however,the electron transfer ability was apparently weakened within the distance from Q_A to Q_B at the receptor side of PSⅡ when tobacco seedling leaves were treated by strong light after low-temperature treatment,which was directly associated with the declined ability of Q_B to receive electrons rather than the indirect consequence of the decrease in PQ capacity.After low-temperature treatment,both the weak and the strong light didn't obviously changed V_L and V_K of tobacco seedling leaves,namely,the strong and the weak light neither decreased OEC activity of tobacco seedling leaves nor dissociated chloroplast thylakoids after the leaves had been treated under low temperature ((8±2)℃) for two hours.Strong light is a crucial factor that induces light inhibition of tobacco seedling leaves after low temperature stress is enhanced,in northern areas,it is advisable to consider transplanting in cloudy days or moderate shadowing at noon in the period of transplanting tobacco in spring,so as to protect the tobacco from strong light.

Key words: Low temperature, High light, Flue-cured tobacco, PSⅡ

中图分类号: 

• Q945.1