Assistant Professor University or British Columbia, Canada
The frequency and severity of drought events and extreme heat waves caused by climate change is increasing and creating challenges for agricultural production. Agroforestry and tree orchards are a component of agricultural production that can provide several ecosystem services such as longer carbon sequestration, low (or no) tillage, and inherent space for cover/intercropping species. However, these systems are also susceptible to climate change due to their long lifespans and the range of increasingly severe conditions in both summer and winter. Hazelnut (Corylus avellana), has remarkably little research regarding its capacity to manage the increasingly dry and hot summer conditions associated with climate change and is worthy of investigation to facilitate sustainable irrigation management. Growers need information on drought susceptibility in hazelnut as well as cultivar-specific water requirements. Therefore, our research goals are to (1) investigate the physiological capacity of hazelnuts to mitigate water stress and (2) develop varietal specific irrigation recommendations to promote precision irrigation and water conservation. To meet these goals, we studied ‘Jefferson’ and ‘Yamhill’ hazelnut cultivars in greenhouse conditions using a new phenotyping approach known as the ‘water potential curve’ (WPC). The WPC seeks to provide indicators of drought tolerance by looking for physiological thresholds such as stomatal closure and turgor loss (wilting) in response to decreasing plant-water status (i.e., stem water potential). Furthermore, we generated a ‘water potential baseline’ using a Scholander pressure chamber to provide growers with baseline water status to help determine the amount of water stress at any given time. Our greenhouse results suggest that based on the WPC, cv. Yamhill may have a better capacity to manage drought stress than Jefferson and this was further supported by measurements direct measurements of leaf turgor and leaf solute potential. Our research on hazelnut irrigation requirements in the field is ongoing, but currently we have generated a water potential baseline that relates atmospheric conditions to plant water status. We will be using this baseline in combination with two automated irrigation treatments (well watered, soil tension of < 30 kPa; and water deficit, soil tension of 30-60 kPa) to investigate the impact of soil tension ranges on plant water usage, growth, stomatal conductance and photosynthesis to help generate irrigation recommendations. As water resources become scarcer due to climate change, knowledge of the drought tolerance and cultivar specific irrigation requirements will help develop agroecosystems with more sustainable water use practices.
