短期昼间亚高温胁迫对番茄光合作用的影响

Effect of short-term daytime sub-high temperature stress on photosynthesis of tomato leaves

为了探讨日光温室春末夏初亚高温环境对番茄光合作用的影响,采用人工气候室模拟环境,在番茄第1花序第1花开花当天,以25℃为对照,研究35℃昼间亚高温处理对番茄光合作用日变化的影响。结果表明:在适宜光照度条件下,3d以下35℃昼间亚高温处理可提高番茄净光合速率,而6d以上昼间亚高温处理可明显降低番茄的净光合速率;同时适宜温度(对照,25℃)处理的番茄净光合速率日变化未出现"光合午休"现象;而35℃昼间亚高温处理的番茄净光合速率日变化出现轻度"光合午休"现象;昼间亚高温处理可提高番茄叶片气孔导度、降低气孔限制值、增加开放气孔的比率、提高胞间CO2浓度和蒸腾速率。这些结果说明,在适宜光照条件下,番茄遭受昼间亚高温胁迫的初期可通过调节自身一些相关反应来适应环境,避免光合速率的降低,而当胁迫时间达到6d以上时则会对光合作用产生不良影响,同时番茄"光合午休"现象不仅与光照度有关,而且与温度有关;昼间亚高温对番茄光合速率的影响与气孔无关,是由非气孔因素限制的。

In order to investigate the effect of short-term sub-high temperature stress on photosynthesis of tomato leaves,the authors utilized artificial climate chamber to simulate 35℃ sub-high temperature environment during the 1st inflorescence flowering,with 25℃ as control to study the effects of short-term sub-high temperature stress on diurnal changes of photosynthesis of tomato leaves.The results showed that：when tomato leaves treated with sub-high temperature at 35℃ for less than three days,it was shown that net photosynthetic rate was higher than that of control, while treated for more than six days, the net photosynthetic rate was lower than that of control in suitable illumination intensity conditions; The diurnal changes of net photosynthesis rate of tomato in suitable temperature treatment（control, 25℃） did not appear ＂midday depression＂, while the diurnal changes of net photosynthesis rate of tomato in sub-high temperature treatment（35 ℃） appeared lightly ＂midday depression＂. The sub-high temperature treatment（35℃） improved stomatal conductance, reduced stomatal limitation, improved the ratio of open stomata, increased intercellular CO2 concentration and transpiration rate. These results illustrate that： in suitable illumination intensity conditions, the tomato which suffered sub-high temperature stress for a short time can adjust some oneself reaction to adapt to environment, in order to avoid the decline of net photosynthetic rate. But when it is treated for more than six days, photosynthetic rate is affected. The ＂midday depression＂ is not just related to illumination intensity, but also related to temperature. The effects of sub-high temperature treatment on net photosynthetic rate is not related to stomatal factors, but to nonstomatal factors.