Modelling temperature effects on growth-respiration relations of maize

The temperature dependence of plant growth rate is related to the temperatu re dependence of respiratory metabolism. To determine how the effects of te mperature on respiration rate and efficiency are transmitted to growth, thi s study measured the dark metabolic heat rate (q) and CO2 production rate ( R-CO2) in excised shoots of seedlings of 14 maize cultivars (Zea mays L.) a t several temperatures. The temperature coefficients of q and R-CO2 differ within a given cultivar and also differ among the cultivars. Both q and R-C O2 exhibit an isokinetic temperature of 20 +/- 3 degrees C, The measured te mperature dependences of q and R-CO2 mere used to model the temperature dep endences of both growth and substrate carbon conversion efficiency. This pr ocedure may be useful in determining the suitability of cultivars for growt h in a given climate and in understanding metabolic adaptation to climate.