Department of Botany, School of General Studies, Australian National University, 2600, Canberra, Australia.
Planta. 1976 Jan;130(2):121-9. doi: 10.1007/BF00384408.
The sites and pathways of transpiration from leaves of Avena sterilis L. var. Algerian were studied using the accumulation of monosilicic acid as a tracer for water movement. Seedlings of Algerian oats were grown under silicon free conditions and fed monosilicic acid, in a normal nutrient solution, via the roots. The silicon component of monosilicic acid was located in freeze substituted tissue by means of x-ray microprobe analysis. Methods of tissue fixation preventing post treatment movement of tracer were developed and it was determined that monosilicic acid is a suitable tracer for water.Sites of water loss were marked by accumulation of silicon. Internal evaporating surfaces having a high intensity of water loss were demonstrated. Evaporation from epidermal surfaces was most intense over the guard and subsidiary cells with very little evaporation from the cuticular surfaces of normal epidermal cells. Moderately high evaporation occurred from epidermal fibre cells located above the veins. Evaporation from all exposed walls of guard cells including the wall adjacent to the pore was intense. Smaller amounts of tracer were located in the unexposed anticlinal walls of epidermal cells as well as within the unexposed walls of mesophyll cells. The results are interpreted as demonstrating the extent of internal transpiration surfaces and that cuticular epidermal transpiration is low. Strong support is given to the existence of peristomatal transpiration. Internal pathways of water movement are defined and the occurrence of these is discussed in relation to cuticular transpiration and lateral water movement in the epidermis.
利用单硅酸的积累作为水分运动的示踪剂，研究了黑麦草（Avena sterilis L. var. Algerian）叶片的蒸腾部位和途径。在无硅条件下种植阿尔及利亚燕麦幼苗，并通过根部在正常营养溶液中用单硅酸喂养。通过 X 射线微探针分析，在冷冻替代组织中定位了单硅酸中的硅成分。开发了防止示踪剂处理后移动的组织固定方法，并确定单硅酸是一种适合的水分示踪剂。水分损失部位通过硅的积累来标记。具有高强度水分损失的内部蒸发表面得到了证明。表皮表面的蒸发最为强烈，主要是在保卫细胞和附属细胞上，而正常表皮细胞的角质层表面几乎没有蒸发。位于叶脉上方的表皮纤维细胞也有中等程度的高蒸发。所有暴露的保卫细胞壁（包括与孔相邻的壁）的蒸发都很强烈。在表皮细胞的未暴露的垂周壁以及叶肉细胞的未暴露的壁内也有少量示踪剂定位。结果表明，展示了内部蒸腾表面的程度，并且角质表皮蒸腾作用很低。为存在周皮蒸腾作用提供了强有力的支持。定义了水分内部运动的途径，并讨论了这些途径与角质蒸腾作用以及表皮中的侧向水分运动的关系。
