不同耐性烟草品种苗期叶片光合特性对低温胁迫的响应

对不同耐性烟草苗期叶片的光合特性在低温胁迫及其随后常温恢复生长条件下的变化进行了详细研究。结果表明,4~6℃的低温胁迫几乎完全抑制较耐冷烟草品种‘K326’和敏感品种‘云烟97’幼苗的生长,但在恢复至常温条件时‘K326’的生长速度显著高于‘云烟97’。低温胁迫降低烟草幼苗叶片的光合作用,而且胁迫时间越长,抑制效应越明显,处理6天后叶片气体交换参数净光合速率（Pn）、气孔导度（Gs）、胞间CO2浓度（Ci）、蒸腾速率（Tr）、水分利用效率（WUE）、气孔限制值（Ls）以及叶绿素荧光参数最大光化学效率（Fv/Fm）、PSII量子产量或光能捕获的效率（ΦPSII）、表观电子传导率（ETR）和非光化学猝灭系数（NPQ）均与处理前的差异达到显著水平。恢复至常温生长条件时,幼苗叶片光合作用迅速得以增强,‘K326’提高的幅度比‘云烟97’大;虽然恢复至第9天时这2个品种的光合作用还没有恢复到处理前的水平,但较耐冷品种‘K326’的光合作用参数与处理前的差异较小,而低温敏感品种‘云烟97’与处理前仍存在显著性差异。

Response of Leaf Photosynthetic Characteristics of Two Different Tolerant Tobacco Cultivars at Seedling Stage to Low Temperature Stress

The changes in leaf photosynthetic characteristics of two different tolerant tobacco cultivars at seedling stage under low temperature stress and subsequent room temperature condition were investigated in the paper. The results showed that the seedling growth of the moderate tolerant tobacco cultivar‘K326＇and the sensitive one‘Yunyan 97＇was nearly inhibited completely at low temperature stress from 4℃ to 6℃, while the growth rate of‘K326＇ was significantly higher than that of‘Yunyan 97＇under subsequent room temperature. The leaf photosynthesis at seedling was reduced under low temperature stress, and the inhibitory effects became worse with the elongation of stress treatment. The leaf photosynthetic indexes such as net photosynthetic rate （Pn）, stomatal conductance （Gs）, intercellular CO2concentration （Ci）, transpiration rate （Tr）,water use efficiency （WUE）, stomatal limitation （Ls）, maximum photochemical efficiency of photosystem II （Fv/Fm）, quantum yield of electron transport （ΦPSII）, apparent electron transfer rate （ETR） andnon-photochemical quenching co-efficient （NPQ） under low temperature for 6 days were significantly different with the untreated control. The leaf photosynthesis of tobacco seedlings was raised under subsequent room temperature condition, and the increasing range in‘K326＇was much more than that of‘Yunyan 97＇. Although the leaf photosynthesis of the both two cultivars under subsequent room temperature for 9 days was not restored to the levels before low temperature stress, the leaf photosynthetic indexes in the moderate tolerant cultivar ‘K326＇were only a little lower than untreated seedlings, while these indexes in the sensitive cultivar‘Yunyan 97＇were still significantly different with the untreated ones.