Table II.

Leaf apoplastic pH and NH4 +concentration and calculated NH3 compensation points of 11-week-old L. perenne and B. erectus

Grass SpeciesN TreatmentNH4+ConcentrationpHCalculated Compensation Point
μm nmol mol−1
L. perenne KNO3 21 ± 56.7 ± 0.10.6 ± 0.1
NH4HCO3 49 ± 126.2 ± 0.10.8 ± 0.2
NH4HCO3 × 2170 ± 386.3 ± 0.12.5 ± 0.7
B. erectus KNO3 33 ± 166.4 ± 0.11.0 ± 0.8
NH4HCO3 45 ± 196.6 ± 0.11.8 ± 1.0
NH4HCO3 × 2369 ± 816.5 ± 0.110.4 ± 2.6

Plants were grown for 6 weeks with different N treatments (3 mm KNO3, 3 mmNH4HCO3, or 6 mmNH4HCO3) in the nutrient solution. Values are means ± se of four replicate samples.