Differences in growth-economics of fast vs. slow growing grass species in response to temperature and nitrogen limitation individually, and in combination

Table 1 Growth parameters

Parameter	N-treatment	Temp (°C)	Bromus erectus	Bromus hordeaceus	Test statistics
Parameter	N-treatment	Temp (°C)	Bromus erectus	Bromus hordeaceus	t	df	p
RGR (mg/gd)	FA	7	109	74
		20	113	192
		30	85	82
	LA	7	71	60
		20	81	135
		30	76	77
NAR (g /m²d)	FA	7	8.2	4.2
		20	3.4	4.6
		30	3.6	4.0
	LA	7	2.1	1.8
		20	3.6	4.1
		30	3.3	3.2
SLA (m²/kg)	FA	7	17 ± 2.3	30 ± 8.1	9.2	8	0.00
		20	47 ± 5.3	57 ± 9.3	2.6	8	0.02
		30	41 ± 27.5	34 ± 19.0	0.8	8	0.21
	LA	7	59 ± 5.4	58 ± 9.7	6.8	8	0.00
		20	33 ± 6.4	54 ± 3.7	4.8	8	0.00
		30	44 ± 12.3	53 ± 15.2	1.0	9	0.17
R:S ratio	FA	7	0.52 ± 0.04	0.63 ± 0.06	0.9	12	0.18
		20	0.42 ± 0.03	0.39 ± 0.02	0.1	12	0.46
		30	0.40 ± 0.02	0.37 ± 0.02	0.7	12	0.26
	LA	7	0.46 ± 0.03	0.63 ± 0.06	1.4	12	0.08
		20	0.47 ± 0.04	0.56 ± 0.05	0.8	12	0.22
		30	0.84 ± 0.19	0.83 ± 0.14	0.1	12	0.47
NUE (g/g)	FA	7	252.7 ± 13.8	221.1 ± 17.9	3.1	8	0.01
		20	205.1 ± 8.4	187.2 ± 7.2	3.6	8	0.01
		30	277.7 ± 19.8	216.6 ± 18.8	5.0	8	0.00
	LA	7	241.4 ± 12.8	270.0 ± 31.7	1.9	8	0.05
		20	296.7 ± 22.1	286.9 ± 7.7	0.9	8	0.18
		30	442.5 ± 103.6	208.4 ± 15.7	3.4	8	0.00

Mean relative growth rate (RGR, mg/g d), net assimilation rate (NAR, g/m⁻² d) and specific leaf area (SLA, m²/kg), root to shoot ratio and nitrogen use efficiency NUE (g/ g) of the fast-growing Bromus hordeaceus and the slow-growing Bromus erectus, when grown at 7 °C, 20 °C, or 30 °C, with free access (FA) or 50% access (LA) nitrogen
SLA, R:S ratio and NUE values are the average of 5 plants sampled with a fully expanded third leaf (± standard deviation). Test statistics show results from T-tests between the species

ISSN: 1472-6785