Dushan Kumarathunge
I consider myself as a plant ecophysiologist with special interest of understanding how forest trees respond to global warming. At present, I serve as a Senior Lecturer attached to the Department of Agricultural Biology, Faculty of Agriculture, University of Sri Lanka.
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News
Dushan received the Research Science Award offered by the Australian Society of Plant Scientists at the ComBio2018-Sydney
Research Highlights
Understanding how tree growth is affected by rising temperature is a key to predicting the fate of forests in future warmer climates. Current knowledge on how trees respond to increasing temperature has been made through the temperature warming experiments conducted under well-watered conditions. There is surprisingly little information on the interactive effects of temperature and water availability on trees growth. Hence, making it challenging to predict the forests responses to warming. In this study, we experimentally resolved the potential effects of water limitation on the temperature response of growth of the widely distributed species Eucalyptus tereticornis. We grew E. tereticornis in an array of six growth temperatures spanning from 18 to 35.5°C with two unique watering strategies i) water inputs constant for all temperatures, matching demand for coolest grown plants and ii) water inputs increasing with temperature to match plant demand at all temperatures. The temperature optima for both photosynthesis and growth were reduced by ~2-3°C under constrained water inputs relative to well-watered, from 28°C to 25°C (for final mass) and 29°C to 27°C (for photosynthesis). The reduction in photosynthesis could be attributed to lower leaf water potential and consequent stomatal closure. The reduction in growth was a result of decreased photosynthesis and reduced total leaf area display and specific leaf area.
This figure shows the temperature response of plant growth under two watering strategies; well watered (Wet) and watering held constant (Dry) . We found that these differences in Topt for growth decreased by ~3 degrees C when plants were grown under constrained water inputs
Read full text here: Kumarathunge et al (2020). The temperature optima for tree seedling photosynthesis and growth depend on water inputs. Global Change Biology. 26: 2544– 2560.
Temperature dependence of leaf photosynthesis (An-T response) is a key determinant in plant growth. It is known that there are differences in the optimum temperature for net photosynthesis (Topt) across species. However, it’s unknown the mechanisms contribute to these differences in optimum. Additionally, it is unknown whether differences across species are largely genetic (adaptation) or plastic (acclimation). We quantified and modelled key mechanisms responsible for photosynthetic temperature acclimation and adaptation using a global dataset of photosynthetic CO2 response curves including data from 141 tree species from tropics to Arctic tundra. We separated temperature acclimation and adaptation processes by considering seasonal and common-garden datasets. The observed global variation in the temperature optimum of photosynthesis was primarily explained by changes in biochemistry, rather than stomatal conductance or respiration. We found acclimation to growth temperature to be a stronger driver of this variation, than adaptation to temperature at climate of origin
This figure shows the optimum temperature for photosynthesis of mature plants growing in different biomes. We found that these differences in Topt were primarily determined by the temperature of plants' growing environment rather than the temperature at climate of origin
For more details, please refer to Kumarathunge et al (2018) Acclimation and adaptation components of the temperature dependence of plant photosynthesis at the global scale. New Phytologist. Click Here