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 depende nt on oxygen concentration. The average CO photoproduction was 2.6 +/- 0.3 x 10(10) molecules cm(-2) s(-1) from rice leaves and 2.2 +/- 0.1 x 10(10) m olecules 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 great er (25.7 +/- 1.5 x 10(10) molecules cm(-2) s(-1), n = 2) at the same radiat ion intensity than from live leaves, and responded slowly to changes in oxy gen concentration and light intensity. CO photoproduction showed no correla tion with CO2 concentration or humidity. This indicates that CO photoproduc tion in leaves is not directly controlled by carbon metabolism or stomatal conductance. The lack of dependence on stomatal conductance leads to the co nclusion that the diffusion of CO from inside the leaves to the atmosphere is not a controlling factor for CO photoproduction from rice and maize leav es. (C) 1999 Elsevier Science Ltd. All rights reserved.