When plants suffer from a lack of water, their leaves warm up. This early sign of drought stress can now be shown by a new technology based on satellite data, report Fraunhofer researchers. The method is intended to be used to optimize irrigation in agriculture. In this way, yields can be increased and resources conserved, say the scientists. A sensor system for using the method is to be installed on board the International Space Station ISS in early 2022.
Mankind is faced with a dilemma: the global demand for food is increasing, while yields are falling due to the consequences of climate change and other environmental problems in some regions. Countering this trend with a further expansion of arable land is known to damage the environment again. One motto is therefore: The yields on the existing agricultural land should be improved as gently as possible. One approach to this is to optimize the water supply. Because when plants suffer from a lack of water, they put less energy into the harvested products and the yields are considerably lower. Therefore, simply irrigating excessively is not a good solution, because it wastes water, a resource that is precious in many places. Knowing the water requirements of cultivated plants as precisely as possible is therefore of central importance.
Up until now, however, it has been difficult to effectively record the supply status on huge arable land. Although satellite data have been used for the extensive investigation of plant populations since the 1970s, this has so far not been suitable for the early detection of water shortages. This is because processes are used that recognize the breakdown of the green pigment chlorophyll when plants are not watered enough. “By then it will be too late,” says Max Gulde from the Fraunhofer Institute for Short-Term Dynamics in Freiburg (EMI). “What we need is a technology that reveals within a few hours whether plants are adequately supplied with water.” He and his colleagues have now developed such a method.
Leaf temperatures indicate water requirements
The basis for this is a further developed thermal imaging camera for satellites, which looks at the agricultural areas. The data obtained are then evaluated using special algorithms so that the temperatures on the leaf surfaces of the plants can be determined. As the researchers explain, conclusions about the water supply can be drawn from these values. Because if there is a lack of water, the temperature rises due to lower evaporative cooling, as the plants restrict the release of water through the leaves. “The temperature can change by two to three degrees Celsius within two hours,” says Max Gulde.
Using their calculation methods, the researchers succeeded in calculating disruptive heat that is radiated from the atmosphere, the earth’s surface or from the satellite itself from the data. “Our method now measures to a tenth of a degree and resolves the temperature differences very finely,” says Gulde. Tests of the system by the European Space Agency (ESA) finally confirmed the efficiency of the process: “The ESA informed us that this was a real breakthrough. No one before us had been able to solve the problem of temperature measurement in such a compact way, ”says Gulde.
Potential for agriculture
Apparently, the information can be used for practical use without any problems, reports the Fraunhofer-Gesellschaft: The data can be downloaded from the satellites to ground stations, processed in data centers and then prepared for users. They could then be made available to agricultural users in the form of an app. The key advantage of the concept is that information about the water supply for plants is available very quickly. Farmers can use it to adjust their irrigation practically in real time and specifically water the fields or plants that need it. Precise and needs-based irrigation can then also help to prevent the often valuable resource water from being wasted.
The Fraunhofer-Gesellschaft reports that the new technology should go into operation in space on board the International Space Station as early as the beginning of 2022. For the further development and marketing of the technology, Gulde and his colleague Marius Bierdel from EMI founded the spin-off company ConstellR. “I am very pleased that the technologies developed at the institute will help to optimize the irrigation of fields and arable land around the world. They improve food security for people and therefore represent significant progress, especially in times of climate change, ”says Frank Schäfer from the System Solutions department at the Fraunhofer Institute for Short-Term Dynamics.
Source: Fraunhofer Society