Relationship between postillumination burst of CO2 and enhancement of respiration in tail fescue leaves

The postillumination burst (PIB) of CO2 and light-enhanced dark respiration (LEDR) depending on oxygen concentration, temperature, respiratory substra tes and photorespiratory inhibitor aminoacetonitrile (AAN) were investigate d in detached leaves of tall fescue (Festuca arundinacea) using a closed ci rcuit system with an infrared gas analyzer. No PIB was observed in 1 % O-2 under temperature over the range from 15 degrees C to 35 degrees C. The rat e of LEDR was about twice as low in 1 % O-2 as that in 21 and 50 % O-2 unde r all temperatures applied. The PIE was absent and LEDR decreased at 21 % O -2 following illumination of leaves for 1 hour at 1 % O-2. When 200 mM glyc ine or malate solutions were introduced into the leaves of tall fescue, the magnitudes of PIE increased by about 60 and 30 % and rate of LEDR by about 70 % and 40 %, respectively. Pyruvate and succinate were less effective in promotion of PIB and LEDR. AAN had a small stimulatory effect on PIB and L EDR (about 20 % and 10 %, respectively). The dependences between magnitudes of PIB and rates of LEDR were highly correlated (r = 0.94). The results pr esented indicate that atmospheric concentration of oxygen during the period of photosynthesis of tall fescue leaves was necessary not only for occurre nce of PIB and LEDR but also for production of substrate(s) (glycine and/or malate) for these phenomena.