Plant water use under heat

Increased leaf temperatures are one of the most important environmental consequences of global climate change on plants. Heatwaves have more than tripled, warmed by 2.3K and usually combine with drought. The impact of heat on plants is intrinsically tied to plant water use. When heat combines with drought, it is advisable for plants to close stomata and completely halt water loss. However, water loss continues through the cuticle and incompletely closed stomata, together constituting the leaf minimum diffusive conductance for water vapour (gmin), which plays an important role for plant water use during heatwaves. Responses of gmin to heat are hardly understood.

The leaf minimum diffusive conductance for water vapour will be studied in functionally divers plant groups from the temperate alpine zone (Mt. Patscherkofel, Innsbruck, Austria) and in tropical areas (Chitwan National Park, Sauraha, Nepal). Methods employed include micrometeorology, infrared thermography, heat tolerance tests (HTTS, HCC-6), psychrometry (PSYPRO), scanning electron microscopy (SEM), RAMAN imaging, differential scanning calorimetry (DSC) and in vivo chlorophyll fluorescence.

The outcomes of the study appear significant for assessment of future heat risk to plants in a globally warmer world with anticipated increased frequency and severity of droughts. The results will allow scientists and breeders to modify heat-testing assays to match biome-specific parameters and to develop heat resistant cultivars for hot and dry regions.

The project is based on a cooperation between the Department of Botany of the University of Innsbruck (G. Neuner), the Institute of Biophysics of the University of Natural Resources and Life Sciences, Vienna (N. Gierlinger) and Tribhuan University, Kathmandu, Nepal (Biva Aryal).