CHANGES IN GAS-EXCHANGE CHARACTERISTICS AND WATER-USE EFFICIENCY OF MANGROVES IN RESPONSE TO SALINITY AND VAPOR-PRESSURE DEFICIT
CHANGES IN GAS-EXCHANGE CHARACTERISTICS AND WATER-USE EFFICIENCY OF MANGROVES IN RESPONSE TO SALINITY AND VAPOR-PRESSURE DEFICIT
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DOI：
10.1007/bf00378237
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发表时间：
1989-01-01
期刊：
影响因子：
2.7
通讯作者：
SIM, RG
中科院分区：
文献类型：
--
作者：
CLOUGH, BF;SIM, RG
在澳大利亚东北部和巴布亚新几内亚的9个不同盐度和气候条件的河口，对19种红树林的光合气体交换特性和水分利用效率进行了测定。气孔导度和CO2同化率在同一地点的物种之间的差异显着，盐分泌的物种，白骨壤，始终具有最高的CO2同化率和气孔导度。气孔导度和CO2同化速率的比例变化导致暴露于800 μ mol·cm·dot以上的光子通量密度的叶的恒定和相似的胞间CO2浓度。m ~（-2）s ~（-1）在特定地点的所有物种中。因此，同一地点的所有物种都具有相似的水分利用效率。然而，不同地区之间的气体交换特性存在显着差异。气孔导度和CO2同化速率均随盐度的增加和叶片与空气的水汽压差（VPD）的增加而降低。此外，同化率和气孔导度之间的关系的斜率增加，而胞间CO2浓度下降，随着盐度的增加和环境相对湿度的降低。从这些结果可以得出结论，红树林的水分利用效率随着环境压力的增加而增加，在这种情况下是干旱，从而最大限度地提高光合固碳，同时最大限度地减少水分流失。
Measurements were made of the photosynthetic gas exchange properties and water use efficiency of 19 species of mangrove in 9 estuaries with different salinity and climatic regimes in north eastern Australia and Papua New Guinea. Stomatal conductance and CO2 assimilation rates differed significantly between species at the same locality, with the salt-secreting species, Avicennia marina, consistently having the highest CO2 assimilation rates and stomatal conductances. Proportional changes in stomatal conductance and CO2 assimilaton rate resulted in constant and similar intercellular CO2 concentrations for leaves exposed to photon flux densities above 800 .mu.mol .cntdot. m-2 s-1 in all species at a particular locality. In consequence, all species at the same locality had similar water use efficiencies. There were, however, significant differences in gas exchange properties between different localities. Stomatal conductance and CO2 assimilation rate both decreased with increasing salinity and with increasing leaf to air vapour pressure deficit (VPD). Furthermore, the slope of the relationship between assimilation rate and stomatal conductance increased, while intercellular CO2 concentration decreased, with increasing salinity and with decreasing ambient relative humidity. It is concluded from these results that the water use efficiency of mangroves increases with increasing environmental stress, in this case aridity, thereby maximising photosynthetic carbon fixation while minimising water loss.