■在高水位期间,自然湿地中可能会发生部分或完全淹没树木,但是在过去的几十年里,淹没事件的严重性和频率都在增加。红豆杉以耐涝而闻名,但是也有许多观察到该物种在更长的时间内被部分或完全淹没。因此,本研究的目的是表征沉水时间的水下净光合作用(PN)和叶片解剖。
■我们完全淹没了6个月大的T.distichum幼苗,并在水下诊断(PN),疏水性,气膜厚度,在30天淹没事件期间离散时间点的叶绿素浓度和针叶解剖结构。我们还构建了水下PN对CO2,光和温度的响应曲线。
■在30天的淹没期间,没有观察到生长或形成新叶,因此,T.distichum对淹没表现出静止反应。在浸没事件期间,针的疏水性下降,导致气膜完全损失。然而,针叶的叶绿素浓度也显著下降,并且无法确定水下PN相应显着下降的主要原因。然而,即使在30天完全淹没之后,在最佳的光照和CO2条件下,针头仍然保留了一定的水下光合作用能力。
■然而,为了充分理解T.distichum惊人的淹没能力,我们建议未来的研究集中在解开针解剖和生物化学的细节,因为这些变化发生在淹没过程中。
UNASSIGNED: Partial or complete submergence of trees can occur in natural wetlands during times of high waters, but the submergence events have increased in severity and frequency over the past decades. Taxodium distichum is well-known for its waterlogging tolerance, but there are also numerous observations of this species becoming partially or complete submerged for longer periods of time. Consequently, the aims of the present study were to characterize underwater net photosynthesis (PN) and leaf anatomy of T. distichum with time of submergence.
UNASSIGNED: We completely submerged 6 months old seedling of T. distichum and diagnosed underwater (PN), hydrophobicity, gas film thickness, Chlorophyll concentration and needles anatomy at discrete time points during a 30-day submergence event. We also constructed response curves of underwater PN to CO2, light and temperature.
UNASSIGNED: During the 30-day submergence period, no growth or formation new leaves were observed, and therefore T. distichum shows a quiescence response to submergence. The hydrophobicity of the needles declined during the submergence event resulting in complete loss of gas films. However, the Chlorophyll concentration of the needles also declined significantly, and it was there not possible to identify the main cause of the corresponding significant decline in underwater PN. Nevertheless, even after 30 days of complete submergence, the needles still retained some capacity for underwater photosynthesis under optimal light and CO2 conditions.
UNASSIGNED: However, to fully understand the stunning submergence tolerance of T. distichum, we propose that future research concentrate on unravelling the finer details in needle anatomy and biochemistry as these changes occur during submergence.