Effects of salicylic acid and zinc applications on antioxidant enzyme activity, proline, carotenoid, chlorophyl content in Galanthus elwesii Hook

Snowdrop is an important genus used for medicinal purposes due to the valuable secondary metabolites it contains. This research was carried out to investigate the effects of foliar applications of different doses of zinc and salicylic acid on the antioxidant enzyme activity, proline, chlorophyll and carotenoid content of Galanthus elwesii Hook. The experiment was established as a pot experiment in the 2021-2022 growing period with five replications according to the randomized plots factorial experimental design. Zinc doses (0, 40, 80 and 120 mM) and salicylic acid doses (0, 0.5, 1 and 2 mM) were applied to all plants by foliar spraying at the beginning of the flowering period. Ascorbate peroxidase enzyme activity (APX), catalase (CAT) enzyme activity, proline, chlorophyll and carotenoid contents were determined in the harvested fresh leaf samples. An increase in the ascorbate peroxidase enzyme activity was observed at all doses of zinc in Galanthus elwesii Hook strain. While a significant increase was observed in catalase enzyme activity up to 80 mM zinc dose, zinc and salicylic acid applied at the highest doses (120 mM zinc-2 mM salicylic acid) decreased the catalase enzyme activity by 19% compared to the control group and had a toxic effect. The amount of proline increased 12.4 times in plots treated with 0 (control) zinc-0.5 mM salicylic acid compared to the control group. It was determined that doses of 40 mM zinc-2 mM salicylic acid increased lipid peroxidation 1.75 times. Total chlorophyll, chlorophyll a and chlorophyll b amounts in snowdrops increased significantly compared to the control environment. It was detected that 120 mM zinc-2 mM salicylic acid applied in the plot increased the total amount of 'chlorophyll' 2.27 times, 40 mM zinc-1 mM salicylic acid applied in the plot increased the amount of 'chlorophyll a' 2.41 times, 0 mM zinc-0.5 mM salicylic acid applied in the plot increased the amount of 'chlorophyll b' 1.54 times. It was determined that the amounts of carotenoids increased 3.95 times in the plot where 0 mM zinc-0.5 mM salicylic acid was applied compared to the control group. As a result, in Galanthus elwesii, zinc and salicylic acid applications showed positive effects on antioxidant enzyme activity, proline, chlorophyll and carotenoid content. It was determined that salicylic acid applications, especially at 0.5 Mm, significantly increased the amounts of proline, chlorophyll b and carotenoid in snowdrop. It has been shown that 120 mM zinc applications have a toxic effect on the plant, but foliar salicylic acid applications have a healing effect.