Uncovering Sugar Beet Water Uptake Through Stable Water Isotope Analysis

The impact of climate change on crop production, marked by increased drought and heat stress, poses significant challenges to agricultural productivity. To overcome these challenges, it is essential to understand how crops take up water through their roots. Sugar beet farming holds immense importance in Austria, especially in the eastern region, where limited water supply constrains crop production. Consequently, strategies need to be developed to enhance water resource utilization and improve plant resilience against drought for sustainable sugar beet production. Therefore, in controlled laboratory experiments, a new method was developed to determine the distribution of water uptake by plant roots in response to dry topsoil conditions and variations in root depth for different sugar beet cultivars. Stable water isotope techniques were used to trace labelled water in rhizobox experiments from the soil to plant transpiration. The water-vapor equilibration technique, commonly used for soil samples, was adapted to measure water-stable isotopes in transpired water on live plants. Leaves were placed in Ziploc bags, inflated with dry air, and allowed to stabilize for at least 16 hours. After equilibration, the bag was punctured, and the equilibrated air and transpired vapor were directed to a laser spectrometer for stable water isotope analysis (²H/¹H, ¹⁸O/¹⁶O). These isotopic ratios provided insights into the depth of root water uptake, aiding in the selection of crop varieties with effective water extraction from deep soil layers. Results indicate that sugar beets develop long roots capable of taking up water from deeper soil layers and adjusting their water uptake mechanisms when topsoil water is scarce. In summary, this study explores the crucial issue of water uptake in sugar beet cultivation, particularly in the context of climate change and water limitations. The findings will inform more efficient agricultural practices, enhance crop resilience, and support sustainable water resource management.