Couchat P, Lasceve G, Audouin P
Service de Radioagronomie, Centre d'Etudes Nucléaires de Cadarache, 13115, Saint-Paul-Lez-Durance, France.
Plant Physiol. 1982 Apr;69(4):762-5. doi: 10.1104/pp.69.4.762.
Experiments were performed on intact sunflowers (Helianthus annuus) placed in a specially designed experimental chamber which allows instantaneous modifications of the atmospheric composition without changing any other conditions. After one night in normal conditions, the plant was illuminated under pure nitrogen atmosphere; the opening stomatal movement, measured as a transpiration rate variation, was inhibited. After an anoxia time period not exceeding one hour, the light was turned off and normal air restored. The stomatal movement was no longer inhibited, and a transient increase in the transpiration rate, referred to here as the postillumination transpiration peak (PITP), was observed.The quantity of transpired water during the PITP can be related to the total incident light energy supplied during the light-nitrogen period. Furthermore, the addition of a dark-nitrogen period between the light-nitrogen and dark-air periods caused the PITP to decrease. The PITP is almost suppressed after a 20-minute dark-nitrogen period.It is shown that the PITP does not result from a hydropassive mechanism but is metabolically controlled. Moreover, it seems that the PITP is not due to a CO(2)-suppression effect during the light-nitrogen period.The results are interpreted in terms of stomatal mechanism. The metabolites leading to PITP originate from the reducing equivalents created during the light-nitrogen period. They could be synthesized at the beginning of the PITP period (darkness under normal air) or during the dark-nitrogen plus CO(2) period between the light-nitrogen and PITP periods. The results obtained are related to the first steps of classical photoactive stomatal opening.
实验是在放置于一个专门设计的实验箱中的完整向日葵（向日葵属）上进行的，该实验箱可在不改变任何其他条件的情况下瞬间改变大气成分。在正常条件下放置一晚后，植株在纯氮气氛中光照；以蒸腾速率变化衡量的气孔开放运动受到抑制。在不超过一小时的缺氧时间段后，关闭灯光并恢复正常空气。气孔运动不再受到抑制，并且观察到蒸腾速率出现短暂增加，在此称为光照后蒸腾峰值（PITP）。PITP期间蒸腾的水量可与光氮期提供的总入射光能相关。此外，在光氮期和暗空气期之间增加一个暗氮期会导致PITP降低。经过20分钟的暗氮期后，PITP几乎被抑制。结果表明，PITP不是由水被动机制引起的，而是受代谢控制的。此外，PITP似乎不是由于光氮期的CO₂抑制作用。结果根据气孔机制进行了解释。导致PITP的代谢物源自光氮期产生的还原当量。它们可以在PITP期开始时（正常空气中的黑暗）或在光氮期和PITP期之间的暗氮加CO₂期合成。所获得的结果与经典光活性气孔开放的第一步有关。
