Table 3.
Parameter | Treatments |
|
+CO2 | –CO2 | |
Total N2 fixation activity before introduction of treatments (mg N plant−1 d−1) | 192±42 | 171±31 |
Total N2 fixation activity 2 d after introduction of treatments (mg N plant−1 d−1) | 283±134 | 126* 50 |
Total N2 fixation activity 21 d after introduction of treatments (mg N plant−1 d−1) | 965±279 | 415*±241 |
EAC 21 d after introduction of treatments | 0.59±0.01 | 0.61±0.11 |
Specific N2 fixation 21 d after introduction of treatments (mg N g−1nodule dry matter d−1) | 43±15 | 39±14 |
N2 fixation activity of an individual nodule 21 d after introduction of treatments (μg N nodule−1 d−1) | 61±40 | 11*±7 |
Plants were grown for 3 weeks with different levels of CO2 concentration in the root/nodule compartment. N2-fixation was calculated from nodule H2 evolution according to Schulze et al. (2006). Data are means of four replicates ±sd. An asterisk indicates a statistically significant difference from the +CO2 treatment (t test, P ≤0.05).