High temperature-related changes in gas-exchange parameters in oak (Quercus spp.) populations

Abstract

One of the first evidence of climate changes is a rising temperature that significantly affects plant physiology. The elevation of temperature is one of the leading problem at the global scale, thus selection of plants with adaptive response to high temperatures is necessary for reforestation process. The key aim of this research was to understand physiological mechanisms involved in high temperature acclimatization. The impact of high temperature (HT) stress in short term exposure was analyzed in two oak species: Pedunculate oak (Quercus robur L.) and Turkey oak (Quercus cerris L.) originating from four populations in different forest localities in Serbia. Eight-month old seedlings were grown under semi-controlled conditions in glasshouse and were exposed to the acute HT stress (temperature range: 42-47 °C) for two and five days. Plant response to HT comprised of different traits, depending on the exposure time, intensity of the heat waves and particularly on the selected population. Elevated temperature led to disturbance of photosynthetic gas exchange parameters, water status, concentration of proline and chlorophyll content. Significant declines of photosynthetic and transpiration rates, water use efficiency and stomatal conductance were observed in all tested populations. In addition, proline content was significantly increased in comparison to control treatment, which might be attributed to the strategies of plants to cope up with heat stress by accumulation of compatible osmolyte. Taking into account all analyzed parameters, it can be concluded that among investigated oak species, population of Q. cerris has the greatest adaptive potential with fast acclimatization response to high temperatures.