The effect of salt stress on spinach leaf color characteristics

In order to determine the adverse effects of salt stress on color of spinach leaves, plants were grown in a climate chamber set at 22/18°C (day/night) temperature, 70% humidity, 10/14 h (light/dark) photoperiod and 400 µmol m‑2 s(‑1) light intensity conditions. In this research ‘Meridien F1’ and ‘San Moreno F1’ cultivars and Hoagland nutrient solution as a hydroponic growing system were used. Salt applications have been started from the period which plants have 4-5 true leaves and continued to harvested time. The salinity of the nutrient solution in the containers has been set up as EC = Control (1.4), 6, 8 and 10 dS m(‑1). Trial coincidence plots were established with 3 replications and at each repetition including 2 cultivars (‘Meridien F1’ and ‘San Moreno F1’) and 4 different salt concentrations (EC = control, 6, 8 and 10 dS m(‑1)) were applied. A total of 24 experimental plots in all, a total of 384 plants were grown in 16 plants in each plot and the entire trial. Spinach leaf color measurements were performed using the Hunter Lab D25LT instrument. Color parameters measured with the instrument; color (darkness-aperture) brightness (L*) and color coordinates (a* and b*). The measurements were carried out in 3 replicates using 3 different plants in each plot and choosing the most advanced leaf from each plant. According to obtained results; while the differences between the values of brightness (L*) and b values of leaves of the ‘Meridian F1’ and ‘San Moreno F1’ cultivars against salt stress were found to be significant with respect to 1%, a* values were statistically insignificant. It was determined that the mean L* value (24,37) of the ‘Meridien F1’ leaves was closer to the dark than the one of ‘San Moreno F1’ (24,99). Leaf color of the cultivars was determined as green (-a). ‘Meridien F1’ (-5,82) was found to be greener than ‘San Moreno F1’ (-5,71). The leaf color b* value of the cultivars was measured as yellow (b+) and the b + (yellow) values (6.20) of the leaves of the ‘San Moreno F1’ cultivars were higher. The color brightness (L*) and color coordinates (a* and b*) were statistically significant at 1% level against increasing salt addition to the control application. According to this, with respect to the control application (1.4 dS m(‑1)), the increase of the salt concentration and the brightness values of the leaves (L*) were found to be colored. With salt application, green color values (-a) of leaves were lower than control, while yellow color value (b+) was increased.