Assessment of three Eucalyptus species resistance (E. camaldulensis, E. microtheca, E.saligna) in the initially stages of growth under Calcium chloride salt stress under laboratory conditions

A large area of world soil have salinity problem. Salinity affects establishment، germination and emergence of plants. Planting salt tolerant species and cultivars is a very convenient and economical way to overcome the problems associated with soil salinity. Various species of Eucalyptus introduced as salt tolerant trees and have widely used around the world. The most important elements dissolved in saline soil that inhibit the growth and crop production are reduced sodium chloride and calcium chloride. In this study has been investigated the effect of calcium chloride as a salt stress on germination and seedling growth of three species (E. camldulensis، E. microtheca and E. saligna) in two substrates، sand and MS medium. The results showed that seed germination has continued until 250 mmol of salinity in both substrates in E. microtheca while the species E. camaldulensis and E. saligna، germinated respectively until 200 and 150 mmol. The maximum and minimum total mean germination (percent and speed germination and seed vigor) and seedling growth (root and shoot length) characteristics in both substrates belong to E. microtheca and E. saligna. Thus، according to the results of this research E. microtheca can be introduced as a more resistance species to salt stress than two other species، E. camaldulensis and E. saligna in germination and primary growth stages.