Impact of short-term exposure to elevated temperatures on physiology of Thai rice (cv. Riceberry)

High temperature is an important limiting factor for the growth and development of rice cultivation worldwide. The current research aimed to investigate the efficiency of PSII system, photosynthetic changes in photosynthetic pigments and membrane stability in Thai seedlings of Thai rice cv. Riceberry after exposure to different temperatures viz., 25, 30, 35, 40, 45, 50 and 55°C for 30 min. The experiment was designed in CRD with four replications. The results showed that the highest F_v/F_m was realized when seedlings were exposed to 30°C and 35°C and decreased when exposed to 40°C for 30 min. The content of photosynthetic pigments such as total chlorophyll (TC) and chlorophyll a (Chl a) were the highest after short-term exposure to a temperature of 25°C. However, the contents of all photosynthetic pigment such as TC, Chl a, Chl b and carotenoids were the lowest when exposed to 55°C for 30 min. The membrane stability of Riceberry seedlings affected on short-term exposure to temperatures of 50°C and 55°C. Thus, Fv/Fm and Hill reaction were the first mechanisms to be significantly affected by the short-term exposure to a temperature of 40°C followed by membrane stability and contents of photosynthetic pigments which were affected by short-term exposure to temperature of 50°C -55°C and 55°C, respectively.