Wageningen University, Department of Plant Sciences, Horticultural Supply Chains Group, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
J Plant Physiol. 2013 Jul 1;170(10):890-8. doi: 10.1016/j.jplph.2013.01.013. Epub 2013 Mar 6.
To better understand the poor regulation of water loss after leaf development at high relative air humidity (RH), the relative importance of the physiological and anatomical components was analyzed focusing on cultivars with a contrasting sensitivity to elevated RH. The stomatal responsiveness to three closing stimuli (desiccation, abscisic acid feeding, light/dark transition), as well as several stomatal features (density, index, size and pore dimensions) and the cuticular transpiration rate (CTR) were determined in four rose cultivars, grown under moderate (60%) and high (95%) RH. Moreover, the effects of changes in stomatal density and pore dimensions on the stomatal conductance (gs) were quantified using a modified version of the Brown and Escombe equation. Higher water loss, as a result of plant growth at high RH, was primarily caused by an increase in residual gs, and to a lesser extent due to higher CTR. It was estimated that in leaflets subjected to desiccation the enhanced gs in high RH- as compared to moderate RH-grown plants was mostly due to poor stomatal functionality and to a lesser extent the combined result of higher stomatal density and longer pore length. It is concluded that the reduced degree and, specially, the reduced rate of stomatal closure are the primary causes of the large genotypic variation in the control of water loss in high RH-grown plants. Furthermore, it was found that although changes in stomatal length have no influence on stomatal functionality, changed anatomical features per se represent a significant and direct contribution to the increased water loss.
为了更好地理解在高相对空气湿度（RH）条件下叶片发育后水分丧失调控不良的原因，本研究着重分析了对高 RH 敏感程度不同的品种，以确定其生理和解剖结构的重要性。在中度（60%）和高（95%）RH 下生长的 4 个玫瑰品种中，测定了气孔对 3 种关闭刺激（干燥、ABA 喂养、光/暗转换）的响应以及几个气孔特征（密度、指数、大小和孔径）和角质层蒸腾率（CTR）。此外，还使用布朗和埃斯科姆方程的改进版本量化了气孔密度和孔径变化对气孔导度（gs）的影响。由于在高 RH 下生长，植物水分丧失增加，主要是由于残余 gs 增加，其次是由于 CTR 增加。据估计，与中度 RH 生长的植物相比，在高 RH 下叶片受到干燥处理时，气孔导度的增强主要是由于气孔功能较差，其次是由于气孔密度增加和孔径长度增加的综合结果。研究结论认为，气孔关闭程度降低，特别是气孔关闭速率降低，是高 RH 生长植物水分丧失控制中存在大的基因型差异的主要原因。此外，研究还发现，虽然气孔长度的变化对气孔功能没有影响，但解剖结构的改变本身就会导致水分丧失的显著直接增加。
