Drought Effects on Morpho-Physiological and Biochemical Traits in Persian Oak and Black Poplar Seedlings

Abstract

In many arid and semi-arid regions, increasing water scarcity pushes woody species to their physiological limits, making strong drought resistance essential for adaptive forest management. Here, we examined morpho-physiological and biochemical drought responses of the forestry-relevant Persian oak (Quercus brantii Lindl.) and black poplar (Populus nigra L.). In a 120-day greenhouse pot experiment, seedlings were subjected to three watering regimes (FC100, FC60, and FC30, indicating percentages of field capacity). Under FC100 conditions, all biomass measures and the total and specific leaf area of oak were significantly greater compared to those of poplar. FC60-exposed poplar seedlings exhibited strong declines in relative water content (RWC; −33%) and carotenoids (−46%) and a surge in electrolyte leakage (EL; +51%), while these parameters did not change significantly in oak. Although both species showed 80% EL under FC30 conditions, poplar suffered more severe drought damage than oak as evidenced by a 65% lower survival, stronger reductions in RWC and total chlorophyll, as well as stronger increases in oxidative stress markers. Accordingly, poplar seedlings displayed a drought-related 56% decline in quality index while only statistically insignificant reductions occurred in oak seedlings. The superior drought resistance of oak seedlings implies economically more viable nursery production and better seedling establishment, suggesting a shift towards Persian oak-dominated forestry in its natural range under future climate projections.

Evaluation of Physiological Changes in Flowering Dogwood under Drought Conditions in a Container Production System

“…Carr. and Prunus sargentii (Rehder) H. Ohba (1992) (Karimi et al 2022). Our study also showed that leaf water potential decreases with increased drought level and increased duration of drought.…”

“…Similarly, Tribulato et al (2019) reported that Polygala myrtifolia L. and Viburnum tinus L. had reduced biomass in both crops, but V. tinus had no differences among treatments with regard to root-to-shoot ratio at four different levels of drought treatments. In a study conducted by Karimi et al (2022), drought-stressed persian oak seedlings (20% field capacity) showed reduced plant height (-22% to -38%) and reduced diameter growth (-20% to -30%) compared with controls. The European black poplar (six genotypes) displayed decreased height (-32% to -88%) and diameter (-40% to -75%) when exposed to drought conditions (Viger et al 2016).…”

In vitro selection of drought-tolerant white poplar clones based on antioxidant activities and osmoprotectant content

“…In addition, greenhouse pot experiment under drought conditions with woody plant species such as pedunculate oak (Kebert et al, 2023), Persian oak (Quercus brantii Lindl.) and European black poplar (Populus nigra L.) also exhibited increased proline content (Karimi et al, 2022). Increased proline levels may be linked to improved plant tolerance to various abiotic stresses, including drought, because of the strong positive correlation between proline and antioxidant potential (FRAP and ABTS) that was observed in this study.…”

“…A similar increasing trend of free proline was also reported in vitro in other plant species such as Prunus dulcis (Mill.) when it was treated with 7.5% PEG 6000 in MS medium (Karimi et al, 2022) as well as in Tacca leontopetaloides (Martin et al, 2021). Other plant species, including rice (Akte et al, 2011), almond (Akbarpour et al, 2017), mango (Pradhan et al, 2021), potato (Kumar et al, 2020), and Fragaria ananasa (Hussein et al, 2017), have also shown a droughtinduced increase in free proline levels.…”

“…Numerous studies have emphasized the importance of increased total antioxidant activity and drought tolerance in different tree plants including Populus deltoides × Populus nigra (Guo et al, 2010); Citrus aurantifolia (Christ.) Swingle) (Jafari and Shahsavar, 2022); Persian Oak and Black Poplar (Karimi et al, 2022); Oaks (Kebert et al, 2022a); Populus przewalskii (Lei et al, 2006); Morus nigra (Özelci et al, 2022); Populus × canadensis (Popovićet al, 2017); Olea europaea L. (Silvestri et al, 2017).…”