Effects of NaCl on growth, yield and ion concentration of various Populus euphratica Oliv. ecotypes in Iran

Abstract

Euphrates poplar (<em>Populus euphratica</em> 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.