Imen Chemlali, Mustapha Ennajeh, Cyrine Abid, Samir Aydi, Noomen Messoudi, Chokri Ben Romdhane, Walid Elfalleh, Ezzeddine Saadaoui
Differential eco-physiological performance of eight Eucalyptus species grown in Tunisian’s arid regions
Dendrobiology 2024, vol. 92: 53-67
https://doi.org/10.12657/denbio.092.004
Abstract:
Successful production of Eucalyptus in drylands requires a thorough understanding of the mechanisms involved in their tolerance to abiotic stress as well as drought. The present study aimed to investigate the effects of dry conditions on morpho-physiological characteristics of eight 5-year-old Eucalyptus species trees, Eucalyptus camaldulensis Dehn., Eucalyptus gomphocephala DC., Eucalyptus torquata Luehm., Eucalyptus microtheca F.Muell., Eucalyptus occidentalis Endl., Eucalyptus diversifolia Bonpl., Eucalyptus sargentii Maiden., and Eucalyptus torwood (Spontaneous hybrid), grew in the same arid microhabitat (a plot) characterized by poor soil. The experiments were conducted in summer 2022, a year that was characterized by a low rainfall rate. Thus, at regular intervals, several parameters were assessed. Plant water status, leaf water relations, gas exchanges, and chlorophyll fluorescence in relation to trees growth performance and leaf traits. Results revealed a distinct resistance level to aridity for the studied species, trees were able to grow showing a clear inter-specific variability. Regarding all species, E. camaldulensis, exhibited a particular behavior to preserve their internal functionality. It displayed simultaneously a rapid growth performance with an ability to develop thinner leaves and earlier stomatal closure under water deficit. Although, E. microtheca, E. gomphocephala, and E. diversifolia’ growth were low, but trees attempted to maintain a stable inter-dependence functions for survival. For E. occidentalis, E. torquata, E. sargentii, and E. torwood, we suggest that a physiological acclimation took place under severe conditions, they showed convergence responses for many parameters. Their ability to maintain good leaves’ succulence and thickness is clearly attributed to a significant RWC (71.5% to 82.4%) related to important LTD, LDMC, and SLW, enabling trees to have important stomata conductance and maintain respectful growth performance. Overall, this comparative study of multiple Eucalyptus species revealed significant variability in their functional and adaptive responses to water deficiency and dry weather conditions, which aids in selecting species that are more appropriate to arid natural environments.
Keywords: Eucalyptus, growth, eco-physiological parameters, plot, aridity