Determination of high temperature stress level in Sarılop fig (Ficus carica L.)

Figs are an important agricultural commodity in Türkiye and are expected to experience substantial changes in both yield and quality under climate change. These changes are driven by climate-related stressors that increasingly constrain fig cultivation and are expected to affect both current and future production. Perhaps the most important of these stress factors is high temperature stress combined with drought, which has become increasingly evident in recent years. This research aims to determine the critical temperature at which high temperature stress begins in figs. Accordingly, the physiological responses to high temperature stress have been examined comprehensively. The study was conducted in 2020 in the climate chamber at the Fig Research Institute using 2-year-old potted fig seedlings of the Sarılop fig variety. In this research, physiological parameters such as leaf water potential, leaf relative water content (%), electrolyte leakage (%), chlorophyll density, and leaf temperature (°C) were analyzed before and after the application of different degrees of high temperature stress conditions. The findings showed that significant physiological changes occur in fig leaves in response to heat stress, particularly a decrease in chlorophyll density, a decrease in leaf relative water content, an increase in electrolyte leakage, and a gradual decrease in leaf water potential. In conclusion, the data revealed that 55°C is the critical temperature value at which physiological responses to high heat stress become pronounced in figs. This finding can be used as a reference value in future heat stress research.