Table 2.

H₂ evolution of M. truncatula nodules after short-term increase of the CO₂ concentration around shoots. Data are given as means of 8 replicates. The electron allocation coefficient (EAC, relative efficiency of nitrogenase) was measured at the beginning and the end of the experiment. Data were compared statistically (within a column) between the points in time of the analysis but showed no significant differences (Tukey’s test, p < 0.05, n = 10; comparison of the EAC by the t-test, p < 0.05, n = 10).

Growth conditions	H2 evolution
	[μmol H2·h−1·plant−1]	EAC
25 °C/400 ppm CO2 around shoots	5.27	0.63
20 °C around nodules
1 h
25 °C/1200 ppm CO2 around shoots	5.31	n.d.
20 °C around nodules
2 h
25 °C/1200 ppm CO2 around shoots	5.35	n.d.
20 °C around nodules
6 h
25 °C/1200 ppm CO2 around shoots	5.38	n.d.
20 °C around nodules
24 h
25 °C/1200 ppm CO2 around shoots	5.24	0.58
20 °C around nodules