Carbon monoxide photoproduction from rice and maize leaves

We investigated CO photoproduction from intact leaves of rice (Oryza sativa L.) and maize (Zea mays L.) by laboratory experiments. CO photoproduction showed positive correlation with light intensity and was positively dependent on oxygen concentration. The average CO photoproduction was 2.6±0.3×1010 molecules cm−2 s−1 from rice leaves and 2.2±0.1×1010 molecules cm−2 s−1 from maize leaves (n=5) at a radiation intensity of 49 mW cm−2. CO photoproduction from senescent rice leaves was 9 times greater (25.7±1.5×1010 molecules cm−2 s−1, n=2) at the same radiation intensity than from live leaves, and responded slowly to changes in oxygen concentration and light intensity. CO photoproduction showed no correlation with CO2 concentration or humidity. This indicates that CO photoproduction in leaves is not directly controlled by carbon metabolism or stomatal conductance. The lack of dependence on stomatal conductance leads to the conclusion that the diffusion of CO from inside the leaves to the atmosphere is not a controlling factor for CO photoproduction from rice and maize leaves