Excessive sunlight can harm not only humans, but also grapes, apples and other fruit. Researchers at the Leibniz Institute for Agricultural Engineering and Bioeconomy (ATB) in Potsdam are collaborating with partners in Hungary and Italy to develop a system for recording and predicting heat damage to fruit crops. This will enable fruit producers to protect their produce at an early stage and in a targeted manner.
“Unlike us humans, apples and other plants need sunlight to produce sugar through photosynthesis. However, excessive heat and UV radiation can also harm them,” explains Dr Manuela Zude-Sasse, Head of the Working Group on Precision Horticulture at ATB. Apples and grapes show a bleaching of the green skin when exposed to low levels of stress. This can be repaired by the fruit after a few hours. Prolonged stress causes browning. Grapes can then wilt on the vine. This is a major problem for fruit growers because browned fruit has a reduced shelf life and cannot be sold due to subsequent microbial spoilage. During prolonged heatwaves, the entire harvest can be lost,” says the expert.
In a joint project with research and industry partners ATB therefore developed a novel sensor system that can detect individual fruits in the tree and measure temperatures directly on the fruit surface. To achieve this, the team combined laser scanners (LiDAR) with thermal imaging cameras to obtain 3D information about the distribution of surface temperatures in the tree canopy.
Dr Zude-Sasse explains: ‘Continuous measurements in the rows of apple trees using this combination of sensors enabled us to gather a wealth of information about the physiological stress response of fruit at high air temperatures.’
Based on this, the team around the researcher developed the Fruit Water Stress Index (FWSI), which for the first time not only describes the water stress of an entire tree crown, but also provides information about the water status of individual fruits.
But how can this knowledge be used to warn fruit growers in good time? Dr Zude-Sasse explains: "Our early warning system uses weather forecasts and actual fruit damage to predict exactly where and when heat damage is likely to occur in the future. A quick glance at a smartphone would be enough to know which plants need special protection on which days. To make such a system work, we combined our 3D temperature maps with temperature curves and measurement data from storage. With the help of AI methods, we were able to develop an initial general risk model."
In the coming years, the researchers will validate their risk model on various fruits under different growing conditions and integrate it into a smartphone app. A prototype can already be downloaded from the Play Store. Fruit growers can also use the app to upload their data to the ATB cloud, thereby improving the system with additional data. This gives fruit producers the opportunity to protect endangered plants precisely, for example using water misting systems that selectively lower the temperature through evaporation or by applying fine sand particles that initially protect against radiation but are then washed away by the rain without leaving any residue. New vines and apple orchards could be planted directly in such a way that less damage occurs due to heat.
With their research, the scientists are making an important contribution to making our agriculture future-proof and climate-resilient, thereby securing our food supply.
Contact:
Dr. Manuela Zude-Sasse
Work group chair Precision Horticulture
Telephone: +49 331 5699-612
E-mail: mzude@atb-potsdam.de
Dr. Ulrike Glaubitz
Presse- und Öffentlichkeitsarbeit
Telephone: +49 331 5699-820
E-mail: uglaubitz@atb-potsdam.de
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