Abstract
The salinity of water and soil decreases the growth and yield of agricultural products. Salinity affects many physiological and morphological processes of plant by influencing soil solution osmotic potential and ion absorption and accumulation of minerals. To evaluate the effect of salinity on some physiological and morphological characteristics of the medicinal plant of Echium amoenum, an experiment was carried out with completely random design in four replications. In this study, the effect of different levels of salinity, including control (non-saline water), 3, 6, 9 and 12 dS m-1 from natural saline water was examined on root length, leaf area, dry weight of roots and shoots, also on the amount of absorption of salts Na+, K+, Cl-, Ca2+, Mg2+ and the ratio of Na+/K+ and Ca2+/Na+ in root and shoot of plants and proline and total soluble sugars of leaf in the vegetative growth stage in the greenhouses. Results indicated that the application of saline water reduces significantly all morphological traits under study. Also, as the salinity increased, the density of K+, Ca2+ and Mg2+ and the ratio of Na+/K+ and Ca2+/Na+ in root and shoot of E. amoenum declined. In contrast, by increasing salinity, Na+ and Cl-concentration in roots and shoots significantly increased. As the salinity increased, proline concentration and leaf total soluble sugars also increased significantly compared with the control. The results showed that the accumulation of proline and soluble sugars are good indicators of salinity tolerance. Results also suggest that the plant resists against salinity through osmotic adjustment and ion absorption and sharing within its cells. This process is essential for the survival of plants in saline conditions. Key words: Salinity, Echium amoenum, vegetative growth, ion composition, proline, soluble sugars.
Highlights
Salinity is one of the important issues in world's farmlands
Increasing salinity levels causes a significant decrease in vegetative growth of E. amoenum, in which the morphological changes are probably caused by the reductions in turgor pressure within the cells that restricted cell expansion (Jampeetong and Brix, 2009); the expansion of leaf area is reduced
Moradi and Ismail (2007) found that the cause of decrease of production of dry plant in saline conditions created by irrigation water salinity increased energy costs, reduced carbon capture and photosynthesis per unit leaf area
Summary
Salinity is one of the important issues in world's farmlands. Millions of tons of salt enter the farmlands through irrigation (Kingsbury et al, 1983). Over 800 million hectares of land are salt-affected throughout the world (Munns, 2002). Salt stress results from a number of detrimental processes including the toxic action of Na+ and Cl- ions, the impairment of mineral nutrition, the modification in the water status of the plant tissues and secondary stresses such as an oxidative stress linked to the production of toxic reactive oxygen intermediates (Bajji et al, 1998). Salt tolerant plants have the ability to minimize these detrimental effects by producing a series of anatomical, morphological and physiological adaptations (Hameed and Ashraf, 2008)
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