Determinants of water circulation in a woody bamboo species: afternoon use and night-time recharge of culm water storage.
Determinants of water circulation in a woody bamboo species: afternoon use and night-time recharge of culm water storage.
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DOI：
10.1093/treephys/tpv071
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发表时间：
2015-09
期刊：
影响因子：
4
通讯作者：
Shi‐Jian Yang;Yong-Jiang Zhang;G. Goldstein;Mei Sun;Ren-Yi Ma;K. Cao
中科院分区：
文献类型：
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作者：
Shi‐Jian Yang;Yong-Jiang Zhang;G. Goldstein;Mei Sun;Ren-Yi Ma;K. Cao
为了解木本竹的水分利用策略，采用热耗散法对竹本竹（Bambusa vulgaris Schrader ex Wendland）茎液通量密度（Fd）进行了监测。分析了旱季和雨季白天和夜间的Fd。此外，还研究了木本竹材根压、茎周长和气孔导度的日变化特征，以表征木本竹材维持日水分平衡的机制。无论在旱季还是雨季，日间Fd都以指数方式响应水汽压差（VPD），当VPD从0增加到1 kPa时，Fd的初始值快速增加。随着光强和VPD的增加，Fd和gs在早晨开始迅速增加，但在达到最大值后急剧下降。该木本竹对VPD的Fd响应远快于同一研究地点的代表性乔木和棕榈树，表明其液流和气孔对环境因子变化的响应较快。低处和高处的Fd在上午同时增加，但高处的Fd在下午高于低处的Fd。与此一致的是，在下午，它的茎周长明显减小。因此，与树木不同的是，竹竿的储水不是在上午用于蒸腾，而是在下午。本实验还检测了该木本竹夜间的液流，并将其与根压有关。我们得出结论，这种竹对光照和蒸发需求有快速的液流/气孔响应，并且在下午利用大量的水分储存进行蒸腾，而根压似乎是导致茎储水在夜间补给的机制。
To understand water-use strategies of woody bamboo species, sap flux density (Fd) in the culms of a woody bamboo (Bambusa vulgaris Schrader ex Wendland) was monitored using the thermal dissipation method. The daytime and night-time Fd were analyzed in the dry and rainy seasons. Additionally, diurnal changes in root pressure, culm circumference, and stomatal conductance (gs) were investigated to characterize the mechanisms used to maintain diurnal water balance of woody bamboos. Both in the dry and rainy seasons, daytime Fd responded to vapor pressure deficit (VPD) in an exponential fashion, with a fast initial increase in Fd when VPD increased from 0 to 1 kPa. The Fd and gs started to increase very fast as light intensity and VPD increased in the morning, but they decreased sharply once the maximum value was achieved. The Fd response of this woody bamboo to VPD was much faster than that of representative trees and palms growing in the same study site, suggesting its fast sap flow and stomatal responses to changes in ambient environmental factors. The Fd in the lower and higher culm positions started to increase at the same time in the morning, but the Fd in the higher culm position was higher than that of the lower culm in the afternoon. Consistently, distinct decreases in its culm circumference in the afternoon were detected. Therefore, unlike trees, water storage of bamboo culms was not used for its transpiration in the morning but in the afternoon. Nocturnal sap flow of this woody bamboo was also detected and related to root pressure. We conclude that this bamboo has fast sap flow/stomatal responses to irradiance and evaporative demands, and it uses substantial water storage for transpiration in the afternoon, while root pressure appears to be a mechanism resulting in culm water storage recharge during the night.