Background and Goals
The primary strategy for avoiding drought stress in crop production is currently irrigation. Plant breeders are now pursuing the strategy of avoiding drought stress by early maturation of plants and by selecting for drought resistant varieties. However, the success rate of the latter approach is rather marginal. In this project the principles for selection and production of plants with improved yield stability under drought will be elucidated in the model species maize.
Steps in the process of adaptation to climate change
Step 1: Understand and describe climate change
- Heat waves
- Dry periods
Step 2a: Identify and assess risks - climate effects and impact
Climate change causes crop losses due to drought and heat. The CO2 uptake of the plant causes high water losses. Water deficit is by far the most important yield-limiting factor in crop cultivation. Over 80% of the water evaporation of the soil takes place globally via the transpiration of plants. Periods of drought and heat, especially in times of climate change, can lead to significant crop losses. In Bavaria, mainly cultivated areas with low water retention of the soils are affected, as they are to be found in Franconia and parts of Old Bavaria.
For this reason, maize is used to study the optimization of their water efficiency.
Step 3: Develop and compare measures
New insights into the mode of operation of plant stress signaling pathways allow approaches to the targeted selection of drought-resistant plants, which are characterized by lower water consumption in growth processes. The project investigated the physiology of adaptation to climate-related water deficit and the molecular mechanisms involved in maize. Measurements on different maize lines showed increasing water use efficiency as drought progressed, but also differences in water use efficiency.
Plants have the ability to significantly increase the efficiency of carbon uptake in the event of a water shortage. Analyzes of the gas exchange record the carbon dioxide uptake, which is necessary for biomass formation, and the water vapor release and showed clear differences between maize and wheat. Maize responds to decreased transpiration, d. H. Reduction of stomata, with a strong reduction of photosynthesis. In wheat this is far less pronounced. Plants with permanent carbon-efficient gas exchange draw less water from the soil, which is available as a reserve of the plant in dry weather. A permanent carbon-efficient gas exchange could be achieved by modest activation of a stress signaling pathway in model plants. This strategy results in reduced soil drought and dry resistance during dry periods.
On the balance sheet, the analysis shows that maize is highly optimized in terms of water use. In contrast to wheat, a reduction in leaf transpiration of maize results in a significant decrease in photosynthetic performance and growth.
Bavarian State Ministry of the Environment and Consumer Protection
Technical University of Munich