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.