Stem Photosynthesis Affects Hydraulic Resilience in the Deciduous <i>Populus</i><i>alba</i> but Not in the Evergreen <i>Laurus nobilis</i>
2021
Patrizia Trifilò | Sara Natale | Sara Gargiulo | Elisa Abate | Valentino Casolo | Andrea Nardini
Stem photosynthesis has been suggested to play relevant roles to cope with different biotic and abiotic stress factors, including drought. In the present study, we performed measurements of stem hydraulic conductance and non-structural carbohydrate content in the evergreen <i>Laurus nobilis</i> L. and the deciduous <i>Populus</i><i>alba</i> L., subjected to inhibition of stem photosynthesis and successive exposure to a drought-recovery cycle in order to check if stem photosynthesis may be involved in allowing hydraulic recovery after drought stress relief. Stem shading affected the growth of <i>L. nobilis</i> but not of <i>P. alba</i> saplings. By contrast, inhibition of stem photosynthesis was coupled to inhibition of hydraulic recovery following embolism build-up under drought in <i>P. alba</i> but not in <i>L. nobilis</i>. The two study species showed a different content and behavior of nonstructural carbohydrates (NSCs). The differences in NSCs’ trend and embolism reversal ability led to a significant relationship between starch content and the corresponding hydraulic conductance values in <i>L. nobilis</i> but not in <i>P. alba</i>. Our findings suggest that stem photosynthesis plays a key role in the maintenance of hydraulic functioning during drought especially in the deciduous species. This, in turn, may increase their vulnerability under current global climate change scenarios.
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