The effect of salinity on the growth, morphology and physiology of Echium amoenum Fisch. & Mey.

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.