Effects of Hydrogel on Growth and Visual Damage of Ornamental Salvia Species Exposed to Salinity

A greenhouse study at increasing salt concentrations (0, 25, 50, 75 and 100 mM NaCl) with or without hydrogel amendment was conducted during a 10-week period in order to examine growth and aesthetic responses of three Salvia species. Subsequent analyses revealed that 25, 50 and 75 mM NaCl concentrations had a positive impact on the plant growth (plant height, plant width, fresh weight, and root system volume), while 100mM NaCl implied a negative response. The positive effect of the hydrogel was most notable in the plant fresh and dry weight, K+ and Ca2(+) content, and root system volume. The results further indicate that the amended hydrogel provided sufficient amount of available water and ions that are usually in competition and are limited by excessive Na+ ion amounts. The hydrogel also mitigated the negative influence of higher salt concentrations (75 and 100 mM NaCl), thereby decreasing leaf damage, defoliation, and petal loss, while also improving vitality and aesthetic value of S. farinacea and S. coccinea. In S. splendens, the hydrogel contributed to better vitality but slightly decreased decorativeness. Both qualitative (visual salt damage) and quantitative (growth) parameters proved to be reliable criteria for assessing salt tolerance of the studied Salvia species, while ion removal contributes to the understanding of salt tolerance mechanisms and possible usages.