Minimum Daily Respiration of Maize: Relationship to Total Daily Respiratory Carbon Loss, and Effects of Growth Stage and Temperature

Since crop respiration can only be measured in darkness, estimating total daily crop respiration ( R t ) requires knowledge of the quantitative relationship between daytime and nighttime respiration, including the predicted effect of temperature. We measured minimum daily (early morning) respiration ( R min ) in maize ( Zea mays L.) at four different temperatures during the night and at four different growth stages to estimate the respiration response to temperature. In a field experiment, respiration was measured every 2 to 5 h over a 24‐h period at five different growth stages to explore the relationship between R t and R min . The fractional rate change with 10°C temperature increment ( Q 10 ) decreased as the temperature increased. A single function was proposed to describe the respiration response to temperature across all growth stages. The minimum respiration of the day was reached between midnight and 6:00 AM, and R min represented 89 to 57% of R t . Modeling maize respiration assuming a constant Q 10 is inadvisable, since Q 10 varies with temperature. There was no effect of growth stage on Q 10 until 26°C; above this temperature, respiration increased only in older plants. The R t increased over the season as biomass accumulated, but the ratio of R min / R t reached its highest value at silking.