Recovery of diurnal depression of leaf hydraulic conductance in a subtropical woody bamboo species: embolism refilling by nocturnal root pressure.
Recovery of diurnal depression of leaf hydraulic conductance in a subtropical woody bamboo species: embolism refilling by nocturnal root pressure.
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DOI：
10.1093/treephys/tps028
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发表时间：
2012-04
期刊：
影响因子：
4
通讯作者：
Shi‐Jian Yang;Yong-Jiang Zhang;Mei Sun;G. Goldstein;K. Cao
中科院分区：
文献类型：
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作者：
Shi‐Jian Yang;Yong-Jiang Zhang;Mei Sun;G. Goldstein;K. Cao
尽管对不同植物功能群的昼夜用水特征进行了大量研究，但对木本竹草日常用水策略的研究仍然缺乏。我们研究了中国西南地区丰富的亚热带竹种 Sinarundinaria nitida (Mitford) Nakai 的日常用水和气体交换。我们发现，该竹种的茎相对含水量（RWC）和茎导水率（K（s））在白天没有显着下降，而叶片RWC和叶片导水率（K（leaf））在中午与黎明前相比明显下降。 K(叶)的日间损失伴随着中午气孔导度(g(s))和CO(2)同化作用的下降。不同生境中的正根压足以补充叶子中的栓塞。我们的结论是：（i）所研究的竹种不利用茎储水进行日常蒸腾； (ii) K(叶)和gs的昼夜下调具有减缓茎中潜在水分流失并保护茎水力通路免受空化的功能； （iii）由于K（叶）在下午晚些时候没有恢复，竹叶中栓塞的重新填充可能完全取决于夜间根部压力。根部压力的栓塞再填充机制可能有助于这种木本单子叶植物的生长和持久性。
Despite considerable investigations of diurnal water use characteristics in different plant functional groups, the research on daily water use strategies of woody bamboo grasses remains lacking. We studied the daily water use and gas exchange of Sinarundinaria nitida (Mitford) Nakai, an abundant subtropical bamboo species in Southwest China. We found that the stem relative water content (RWC) and stem hydraulic conductivity (K(s)) of this bamboo species did not decrease significantly during the day, whereas the leaf RWC and leaf hydraulic conductance (K(leaf)) showed a distinct decrease at midday, compared with the predawn values. Diurnal loss of K(leaf) was coupled with a midday decline in stomatal conductance (g(s)) and CO(2) assimilation. The positive root pressures in the different habitats were of sufficient magnitude to refill the embolisms in leaves. We concluded that (i) the studied bamboo species does not use stem water storage for daily transpiration; (ii) diurnal down-regulation in K(leaf) and gs has the function to slow down potential water loss in stems and protect the stem hydraulic pathway from cavitation; (iii) since K(leaf) did not recover during late afternoon, refilling of embolism in bamboo leaves probably fully depends on nocturnal root pressure. The embolism refilling mechanism by root pressure could be helpful for the growth and persistence of this woody monocot species.