Morphological and physiological properties and their relations in calendula (Calendula officinalis L.) under salt stress conditions

In this study, the effects of salt stress on morphological and physiological characteristics of calendula (Calendula officinalis L. 'Bon Bon Yellow') were investigated. For this purpose, five different NaCl concentrations (0, 75, 150, 225 and 300 mM) were applied to the plants at the seedling stage. As morphological parameters plant height and stem length, stem thickness, number of leaves, leaf dimensions (width and length and projection area), compactness ratio, fresh and dry weights of root and shoot, R/S ratio and leaf color characteristics (L, a, b, C and h) were determined. As physiological parameters cellular membrane damage, moisture contents of root and shoot, pigment contents (Karotenoit-t, Klf-a, Klf-b, Klf-t), SPAD, photosynthesis activity (Ft and PSII-Fv'/Fm') were evaluated. In general, the increase in NaCl caused a decrease in the vegetative and physiological parameters' values, while this was accompanied by an increase in the membrane damage and the 'L' (blackness/whiteness) and 'a' (greenness/redness) values of the leaves. In addition, the high moisture content at 75 mM and the high compactness ratio in NaCl level up to 150 mM were notable. While the highest values were found at 0 mM for most vegetative and physiological properties, the increase in NaCl negatively affected vegetative growth and development and physiological properties, most notably at 225 and 300 mM.