Drought stress is an important constraint to wheat production, but breeding for drought tolerance remains challenging. Many different traits contribute to the crop’s drought tolerance, and the crop’s drought stress response is highly dependent on the specific characteristics of the drought period. Furthermore, the crop’s drought stress response may differ among developmental stages and even short-term, diurnal adjustments of transpiration can have a positive effect on overall transpiration efficiency. To identify such potentially beneficial diurnal and developmental stage-specific transpiration patterns, precise, continuous, and automated phenotyping of traits related to water use and transpiration efficiency is required. “Real-time” phenotyping allows monitoring of diurnal transpiration patterns, for example regulation of transpiration around midday in response to elevated vapour pressure deficits. In our study, 79 elite winter wheat lines were evaluated for transpiration efficiency and diurnal transpiration patterns under drought stress conditions. For this purpose, a custom-built “DroughtSpotter XXL” facility comprising 240 large containers (90 cm depth and 175 kg soil volume) was used to gravimetrically quantify water use and plant transpiration in real-time under semi-controlled, yet field-like conditions. Using a 3D laser scanner, plant growth was repeatedly phenotyped during the growing season. This enabled us to continuously monitor transpiration efficiency and the response of transpiration to changes in vapour pressure deficit, as well as the effects of these traits on yield performance. The resulting high-resolution data enabled us to identify hidden genotypic variation for developmental stage-specific variation for genotype rankings in transpiration efficiency and also for regulation of transpiration under high vapour pressure deficit conditions. In-depth knowledge of these potentially useful traits and how they affect yield provides valuable new information for breeding cultivars with improved drought stress tolerance.
Anna Langstroff, Rod Snowdon (Department of Plant Breeding, Justus Liebig-University Giessen, Germany) and Andreas Stahl (Julius Kühn Institute (JKI) – Federal Research Centre for Cultivated Plants, Institute for Resistance Research and Stress Tolerance, Quedlinburg, Germany)
We thank Andreas Eckert, Maximilian Henning and Bernhard Schick (Justus Liebig-University Giessen, Rauischholzhausen, Germany) for the technical management of the DroughtSpotter experiment. We thank Sabine Frei, Regina Illgner, Birgit Keiner, Annette Plank, Swetlana Renner, Lennart Scheer, Ingrid Schneider-Hüther, Stavros Tzigos and Stjepan Vukasovic (Justus Liebig-University Giessen, Germany) for helping with sample processing and data acquisition. Furthermore, we thank DSV AG, Nordsaat GmbH and W. von Borries-Eckendorf GmbH & Co. KG for providing the breeding lines. This work was funded by the German Federal Ministry of Food and Agriculture (BMEL grant 2818403A18).
