Table 1.

Mean values and ranges of daily photosynthesis and respiration of soybean leaves grown and measured at ambient and elevated [CO₂]

	Ambient			+350 µmol mol−1
Variable	Mean	Range	Mean	Range	Probability
Photosynthesis per area (mmol m−2 d−1)	745	34–1310	1103	45–1670	0·001
Respiration per area (mmol m−2 d−1)	53	22–87	53	23–75	0·751
Respiration per mass (mmol g−1 d−1)	1·55	0·63–2·81	1·25	0·51–2·24	0·002

Means are for 24 h measurements on 16 days over two years, with a pair of leaves measured at both [CO₂] on a given day. Ranges indicate day-to-day differences in average values. ‘Probability’ is the probability of obtaining a larger t-value under the hypothesis of no [CO₂] treatment effect, using paired t-tests.