چکیده:
Euphrates poplar (Populus euphratica Oliv.) is a woody species that is naturally distributed in the desert areas of some parts of Asia and Africa. Because of its outstanding features, it is a model plant to study environmental stress tolerance. This research was conducted from 2014 to 2016 in order to study the relationship between performance indices and ion concentrations. The cuttings of 12 ecotypes were collected from different climatic conditions in Iran. Salinity stress was applied using four levels of NaCl (75, 150, 225 and 300 mM) and one control sample (salt-free). The performance indices [diameter and height growth, biomass production; leaf, stem, root and total biomass] showed significant differences in salt levels and ecotypes. The ion concentrations showed significant differences in salt levels (except Ca2+) and varied in different ecotypes. There was no significant difference in salt×ecotype interaction for most of the variables. The ecotypes, treatments, (salt levels) means of performance indices and ion concentrations were separated into different groups. Correlation coefficients showed that the concentration of macronutrients had positive correlations with performance indices, and that salt ions had negative correlations. Correlation coefficients also showed that the ion concentrations had synergistic or antagonistic effects on each other. The results of this study showed that the key mechanisms of salt tolerance in this specie include: exclusion of salt from the root, compartmentalization of Na+ in plant tissue, preventing excessive reduction of K+ absorption resulting in the maintenance of the K+/Na+ balance.
خلاصه ماشینی:
The performance indices [diameter and height growth, biomass production; leaf, stem, root and total biomass] showed significant differences in salt levels and ecotypes.
The ecotypes, treatments, (salt levels) means of performance indices and ion concentrations were separated into different groups.
P. euphratica can withstand up to to 450 mM NaCl under hydroponic conditions and can tolerate high Na+ and Cl– concentrations in its roots and leavesafter exposure to a salinity of 300 mM NaCl for 1 month (Chen and Polle, 2010; Gu et al.
001) in performance indices [diameter and height growth, biomass production; leaf, stem and root biomass (dry weight) and total biomass] at different salinity levels and different ecotypes.
Duncan’s Multiple Range Test for variables in different salt levels showed that the highest {مراجعه شود به فایل جدول الحاقی} freshness and diameter growth were those of the control specimens, whereas, the cuttings belonging to 75 mM NaCl treatment were in the highest group regarding performance traits such as height growth, biomass production; leaf, stem, root and total biomass (dry weight).
Duncan’s Multiple Range Test for variables in different treatments of salt levels indicated that all of the 12 ecotypes were classified into 5 groups from those with the highest ion concentration, except those of Ca2+ and Mg2+ in leaves and roots.
euphratica's potential to tolerate high salt concentrations is because of its high capacity to exclude Na+ and Cl– ions at the root level (Sun et al.