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 Q<10> may be an important physiological factor determining high crop yield.