STOMATAL RESPONSE TO AIR HUMIDITY AND ITS RELATION TO STOMATAL DENSITY IN A WIDE-RANGE OF WARM CLIMATE SPECIES
STOMATAL RESPONSE TO AIR HUMIDITY AND ITS RELATION TO STOMATAL DENSITY IN A WIDE-RANGE OF WARM CLIMATE SPECIES
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DOI：
10.1007/bf00037004
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发表时间：
1985-01-01
影响因子：
3.7
通讯作者：
HERNANDEZ, AD
中科院分区：
文献类型：
--
作者：
ELSHARKAWY, MA;COCK, JH;HERNANDEZ, AD
研究了19种不同暖气候树种在不同叶片对空气蒸气压差（VPD）条件下的气体交换。随着VPD的增加，所有物种的气孔都趋于关闭，导致净光合作用的减少。在低VPD条件下叶片电导率大的树种，叶片电导率单位增加的绝对降幅最大。即使所有物种的气孔都同样敏感，这也是可以预料到的。然而，净光合作用的减少百分比（用来衡量不同物种气孔的相对敏感性）也与低VPD下的最大导度密切相关。同样，气孔对VPD变化的相对敏感性与加权气孔密度或“拥挤指数”密切相关。提出了不同VPDs的气孔关闭与气孔周围蒸发有关，并结合了表皮与叶肉之间的高阻力和气孔器与表皮细胞之间的低阻力。这一假设与拥挤指数高的叶片上气孔的相对敏感性较高是一致的。通过对叶片两侧气孔密度和分布的观察，讨论了在不同相对湿度和土壤水分有效性条件下的最佳生产力选择的结果和假设。
The gas exchange of 19 widely different warm climate species was observed at different leaf to air vapour pressure deficits (VPD). In all species stomata tended to close as VPD increased resulting in a decrease in net photosynthesis. The absolute reduction in leaf conductance per unit increase in VPD was greatest in those species which had a large leaf conductance at low VPDs . This would be expected even if stomata of all species were equally sensitive. However, the percentage reduction in net photosynthesis (used as a measure of the relative sensitivity of stomata of the different species) was also closely related to the maximal conductance at low VPD. Similarily the relative sensitivity of stomata to changes in VPD was closely related to the weighted stomatal density or ''crowding index''. The hypothesis is presented that stomatal closure at different VPDs is related to peristomatal evaporation coupled with a high resistance between the epidermis and the mesophyll and low resistance between the stomatal apparatus and the epidermal cells. This hypothesis is consistent with the greater relative sensitivity of stomata on leaves with a high crowding index. The results and the hypothesis are discussed in the light of selection, for optimal productivity under differing conditions of relative humidity and soil water availability, by observations of stomatal density and distribution on the two sides of the leaf.