Table 4.

N₂ fixation and H₂ evolution of white lupin plants grown in silica sand with +P or −P nutrient solution

	21 DAI		37 DAI
	+P	−P	+P	−P
N fixed based on 15N2 uptake [nmol N (mg DM nodule)−1 h−1]	75·7	73·6	50·2	2·34*
N fixed based on H2 evolution [nmol N (mg DM nodule)−1 h−1]	58·6	65·2	40·52	3·89*
H2 evolution [nmol H2 (mg DM nodule)−1 h−1]
ANA	61	55	44	15*
TNA	149	153	107	21*
EAC	0·59	0·64*	0·58	0·28*
EAC based on 15N2 uptake and H2 evolution (ANA)	0·65	0·67	0·63	0·19*
N fixed (15N2 uptake) nodule−1 [nmol N nodule−1 h−1]	50·29	34·58*	83·84	2·76*
N fixed (15N2 uptake) total P−1 [nmol N (mg P in plant)−1 h−1]	235·9	321·1*	400·4	105·34*
N fixed (15N2 uptake) nodule P−1 [μmol N (total P in nodules)−1 h−1]	12·26	23·23*	7·58	1·85*

Data are means of six replicates.

ANA, Apparent nitrogenase activity; TNA, total nitrogenase activity; EAC, electron allocation coefficient.

^*Significantly different from the +P treatment, t-test (P ≤ 0·05).