Extended growth period and later leaf discolouration in hazel after drought stress
Understanding how trees and shrubs respond to extreme drought is important in regions experiencing increasing periods of drought due to climate change, such as Flanders.
We investigated the effects of drought stress on hazel. Pot plants were not watered under controlled conditions for 30 days. We then observed and analysed the stress symptoms.
- As expected, the stems of the drought-stressed plants were less thick than those of the control plants that did not experience drought stress. However, it was striking that their growth, although reduced, continued into the autumn, when the control plants had already stopped growing. This indicates a kind of compensatory growth after the drought period.
- Leaf discolouration in autumn occurred up to six days later in most drought-stressed plants than in the control plants. In the most severely affected plants, this was delayed by up to 21 days.
- Bud break in the following spring was also delayed, with the greatest delay again occurring in the most severely affected plants.
In this trial, we investigated not only plants of local origin but also hazel from the Spanish Pyrenees, where the climate is on average colder than ours due to the high altitude. These plants developed smaller leaves and showed less height growth compared to our local hazel. A smaller leaf area and therefore a smaller evaporation surface probably contributed to the slightly later appearance of drought stress symptoms in our experiment.