Effects of Drought and Salinity Stress on Antioxidant Ezymes and Yield Parameters of Laurel Plant (Laurus nobilis L.)

Plants are exposed to various environmental stressors throughout their life cycle, including cold, drought, high temperature, salt, and heavy metals. These environmental variables, known as abiotic stressors, lead to oxidative stress and promote the formation of reactive and dangerous reactive oxygen species in plants. In this study, laurel plants were exposed to two different abiotic stress conditions (salinity (10 dS m-1), drought). Under both stress conditions, chlorophyll content, stomatal conductance and antioxidant enzyme activities Glutathione S-transferase (GST), glutathione reductase (GR), guaiacol peroxidase (GPx), ascorbate peroxidase (APx) were determined. Chlorophyll content was observed to decrease by 58.53% and 40.31% for drought and salinity treatments, respectively, compared to the control treatment. In addition, stomatal conductance was reduced by 52.75% and 35.15% for drought and salinity treatments, respectively. These results indicate that chlorophyll content and stomatal conductance of laurel plants were more affected by drought stress than salinity. The activity of all antioxidant enzymes decreased in both drought and salinity stress. GR and GPx were significantly reduced by 49.29% and 74.51%, respectively, in drought treatment compared to the control group. In addition, GST and APx activity decreased by 22.01% and 6.26%, respectively, in salinity stress compared to the control group. According to the data obtained, GR and GPx enzyme activities in laurel plants were more affected by drought stress, while GST and APx enzyme activities decreased more significantly under salinity stress.