Exploring a New Technique for Measuring the Plant's Sap Flow Based on an Optical Fiber

In agriculture, substantial declines in crop yields are occurring in most agricultural regions of the world, with major implications for livelihoods and food security. Sap flow measurements provide a powerful tool for quantifying plant water use and monitoring qualitative physiological responses of plants to environmental conditions. In this paper the possibility to have optical reflection signal of sap flow is analyzed. A particular configuration of a fiber optical sensing head has been developed and tested. Light signal during daylight hours, when the plant normally transpires, while at night were no movement of fluid can be expected, the signal is blunted, almost null. A U-tube pressure measurement system was also tested and enables to determine the pressure range to be measured and the mean daily sap flux in a plant xylem.