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

Abstract

ABSTRACTSince crop respiration can only be measured in darkness, estimating total daily crop respiration (Rt) requires knowledge of the quantitative relationship between daytime and nighttime respiration, including the predicted effect of temperature. We measured minimum daily (early morning) respiration (Rmin) 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 Rt and Rmin. The fractional rate change with 10°C temperature increment (Q10) 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 Rmin represented 89 to 57% of Rt. Modeling maize respiration assuming a constant Q10 is inadvisable, since Q10 varies with temperature. There was no effect of growth stage on Q10 until 26°C; above this temperature, respiration increased only in older plants. The Rt increased over the season as biomass accumulated, but the ratio of Rmin/Rt reached its highest value at silking.