Development of transpiration stream sensor and stress responses in plants

绿色植物体内的水分传输是维持植物生命的重要环节，从农业工程和植物生理学的角度出发，对植物体内的水分传输进行了考虑植物解剖结构的数值研究。近年来，在作物科学和园艺学中，环境对蒸腾流的影响已被定量研究。然而，由于缺乏一种简单、准确的自然条件下的测定方法，目前还没有足够的基于同时测定的蒸腾速率和吸收速率的定量、可靠的数据。水分运动的驱动力和阻力的模拟和测量：为了研究蒸腾流的机理，测定了三个器官的吸水压力和传递阻力，即，叶、茎、根用电位计法测定。产品介绍 关于我们 叶和根产生的压力是根据零吸收率条件确定的，零吸收率是通过减少施加在浸入水中的根上的静水压力头来实现的。通过三种试验方法估算了三种不同的阻力值。根据实验结果，提出了一个简单的吸水模型。模型预测的结果与实测数据吻合较好。蒸腾速率和吸收速率同时测量方法的发展：在所发展的方法中，在植物浸泡在水中的情况下，使用了两个电子天平。一个天平称量水浴中的水，用于测量吸收损失，另一个天平称量唯一的植物，其根将漂浮在水浴中，用于测量吸收减去蒸腾损失。水分的蒸腾损失由两个平衡之和获得。在根在土壤中的情况下，土壤中的盆栽植物将漂浮在水浴中。在这种情况下，必须考虑浮力对吸收的影响。植物对环境的响应实验：用上述方法研究了水分运动对光照、气温和根系切割的阶跃响应。通过对水中植物和土壤中植物的研究，探讨了植物蒸腾与吸收的关系及水分运动的脉动特征。结果表明，蒸腾速率相对于吸收速率有较大的超调量和相位滞后。另一方面，对断根后的相位关系进行了分析。少

Water transport in green plants is important for maintaining plant life and numerical researches taking account of the anatomy of plants have been presented in the view of agricultural engineering and plant physiology. Recently, in crop science and horticulture the effects of the environment on the transpiration stream have been investigated quantitatively. However, there is not enough of quantitative and reliable data based on simultaneous measurement for the rates of the transpiration and absorption because of the lack of a simple and accurate method of measurement under natural conditions. Water movement must be investigated more thoroughly in the connection between these data and plant physiology.Modeling and measurement of driving forces and resistances to water movement :To investigate a mechanism of transpiration stream, the suction pressures for water absorption and transfer resistances of three organs, i.e., leaves, stem, roots, were measured by the potometer method. Suction p … More ressures due to the leaves and roots were determined from the conditions of zero-absorption rate, which was attained by the reduction of the hydrostatic pressure head applied on the roots immersed in the water. Three values of the resistances were estimated by the three kinds of experiments. Based on the experimental results, a simple model for water absorption was developed. Some results predicted by the model were well consistent with measured data.Development of a method of simultaneous measurement for transpiration and absorption rate :In the developed method in the case of plants immersed in the water, two electronic balances were used. A balance weighs water in the bath for measuring the absorption loss, and the other balance weighs the only plant, root of which are to be floated in the water bath, for measuring the absorption minus transpiration loss. Transpiration loss of water is obtained by the sum of two balances. In the case of the roots in the soil, a potted plant in the soil is to be floated in the water bath. In this case the effect of buoyant force on absorption must be considered. Using these method, instantaneous and accurate measurements were attainable.Experiments of plant responses to environment :Step responses of water movement to illumination and atmospheric temperature, and to cutting of roots were examined, using the above-mentioned method. Relation between the transpiration and absorption, aspect of pulsation of water movement were investigated by using the plants in the water and those in the soil. It was noted that the transpiration rate showed the large overshoot from the steady value and in phase lag to the absorption rate. On the other hand, those phase relation by cutting the roots was conducted reversely. Less