Factors Causing the Variation in the Temperature Coefficient of Dark Respiration in Rice (Oryza sativa L.)

Abstract

The temperature coefficient (Q10) of dark respiration in rice gradually decreased in continuous darkness, fluctuating as the circadian rhythmic variation in dark respiration. The solar radiation (MJ m-2) on the day of measurement and the nitrogen concentration in the culture solution hardly affected the Q10 value. However, the plants exposed to high-intensity light (260W m-2) for two weeks showed a higher Q10 of dark respiration than those exposed to low-intensity light (70W m-2). The seasonal variation in Q10 value was not observed. The average Q10 value during the growth stage measured at 15 to 25°C, 20 to 30°C, and 25 to 35°C was 2.14, 1.76, and 1.56, respectively. High crop yield in the regions where the day/night temperature difference is large may be partly explained by the high Q10 at low night temperature. Thus, the Q10 may be an important physiological factor determining high crop yield.

Keywords

• Circadian rhythm
• Dark respiration
• Rice
• Temperature coefficient
• Yield