Water transport in leaf vein systems and the flow velocity measurement with a new method.

As an exploration to the nature, research about plants' physiological properties have never been suspended. Water transport in leaf vein systems is an essential part of plant growth and development. In this paper, a simple but efficient method combined the fluorescence labeling technology frequently used in bioresearch and the image-processing technology in the computer realm was developed to measure the flow velocity, which was used as a quantitative description to reveal the regulation of water transport in leaf vein systems. Three ordinary species of plants were selected for the experiments and the influence of the experimental conditions, such as the concentration of fluorescein and illumination intensity of LEDs, was investigated. Differences among the flow velocities of different leaf veins of the same leaf as well as the flow velocities of different species were shown in bar charts. The mean measured flow velocities of the midrib and secondary vein of Ficus virens Ait. var. sublanceolata (Miq.) Corner were 4.549m/h and 3.174m/h. As for Plumeria rubra L. cv. Acutifolia and Hamelia patens, that were 0.339m/h and 0.463m/h, 2.609m/h and 2.586m/h, respectively. With the algorithm developed in this paper, the variation of the flow velocity in leaf veins was investigated by setting a constant time interval. Then a verification of the flow velocity measured by the algorithm was performed. Finally, according to the natural conditions of a plant leaf, a simulation about the water transport in leaf vein systems was carried out, which is especially different from the previous research.