The effect of microalgae (Chlorella vulgaris) on some physiologicalcharacteristics of thyme (Origanum vulgare L.) grown under salinity and boron stress

In this study, the aim is to investigate the ameliorative effects of microalgae use on certain physiological parameters of thyme (Origanum vulgare L.), one of Türkiye's valuable medicinal and aromatic plants, in soils affected by salinity and boron toxicity, with the purpose of establishing and ensuring the long-term sustainability of green spaces in urban and rural areas. This experiment was conducted at the Research and Application Greenhouse of Çankırı Karatekin University. Two-year-old thyme plants were planted in pots with a 2 L soil capacity, with one plant per pot. The growing medium consisted of a mixture composed of 4 parts soil, 1 part peat, and 1 part pumice. The experiment was established in a randomized complete block design with four replications, where salinity was applied as a solution of NaCl, and boron toxicity was induced using an H₃BO₃ solution. The findings revealed that certain physiological parameters of the thyme plant (chlorophyll a, chlorophyll b, chlorophyll a+b, carotenoids, chlorophyll a+b/carotenoids, relative water content) exhibited significant reductions due to salt and boron stress. However, the application of microalgae was observed to have positive effects on these parameters and enhanced the plant's resilience against stress conditions. As the amount of microalgae increased, the thyme plant more effectively mitigated the adverse effects of salt and boron stress. In this context, it is recommended that future studies on microalgae focus on optimizing dosage adjustments.