. 2005 Feb;137(2):638–650. doi: 10.1104/pp.104.054759

Table II.

Summary of average steady-state gas exchange parameters, leaf, stem (including sheath), root, and whole-plant N, leaf mass per area, PNUE, NUE, and some growth parameters of NAD-ME and NADP-ME C₄ grasses from three independent experiments (experiments 1–3; Table I)

Maximal phosphoenolpyruvate carboxylase (V_{p max}) and Rubisco (V_{c max}) activities were estimated from A/C_i curves (experiment 2) using the C₄ photosynthesis model of von Caemmerer (2000). Within the same experiment, values followed by the same letter are not significantly different (P > 0.05). −, Not determined. HN, High N soil supply; LN, low N soil supply.

	Experiment 1		Experiment 2		Experiment 3
Parameter	HN		HN		HN		LN
	NAD-ME	NADP-ME	NAD-ME	NADP-ME	NAD-ME	NADP-ME	NAD-ME	NADP-ME
A (μmol m⁻² s⁻¹)	30a^a	33a^a	39a^b	40a^b	35b	35b	25a	24a
g (mol m⁻² s⁻¹)	0.25a^a	0.28a^a	0.26a^b	0.28a^b	0.22b	0.23b	0.16a	0.16a
C_i/C_a	0.37a^a	0.38a^a	0.31a^b	0.33a^b	0.26a	0.26a	0.29a	0.33b
V_{p max} (μmol m⁻² s⁻¹)	–	–	81a	82a	–	–	–	–
V_{c max} (μmol m⁻² s⁻¹)	–	–	47a	46a	–	–	–	–
V_{p max}/V_{c max}	–	–	1.72a	1.78a	–	–	–	–
Leaf N (mmol m⁻²)	119b	70a	115b	88a	108d	81c	47b	37a
Leaf N (mg g⁻¹)	39b	32a	34b	31a	41c	37b	18a	18a
Stem N (mg g⁻¹)	–	–	21b	19a	–	–	–	–
Root N (mg g⁻¹)	–	–	16a	19b	–	–	–	–
Plant N (mg g⁻¹)	–	–	24a	23a	–	–	–	–
Leaf mass per area (g m⁻²)	44b^a	31a^a	42b	37a	36c	31b	35c	28a
A/N (μmol CO₂ [mol N]⁻¹ s⁻¹)	313a	525b	351a	478b	299a	388b	445c	611d
NUE (g dry mass [g leaf N]⁻¹)	67a	111b	95a	116b	65a	88b	191c	218d
Tiller no. (plant⁻¹)	–	–	–	–	10b	16c	4a	5a
Plant dry mass (g plant⁻¹)	9.2a^a	14.6b^a	9.9a^b	10.7a^b	4.4b	4.5b	1.5a	1.3a
Leaf mass fraction (% plant dry mass)	39b^a	33a^a	35b^b	31a^b	41d	35c	32b	28a
Stem mass fraction (% plant dry mass)	50a^a	50a^a	47a^b	54b^b	35c	44d	26a	28a
Root mass fraction (% plant dry mass)	11a^a	17b^a	18b^b	15a^b	24b	21a	42c	44c

Data taken from Ghannoum et al. (2001).

Data taken from Ghannoum et al. (2002).