Table II.

Analysis of variance of fixed effects on photosynthetic and gas-exchange parameters of two leaf cohorts taken from field-grown soybean in current and elevated [O₃]

Cohort 1 (V5, DOY 185)	Day of Year		Treatment		Day of Year by Treatment
		F	P Value	F	P Value	F	P Value
Asat	23.81	<0.0001	1.20	0.3175	3.98	0.0268
Vc,max	65.46	<0.0001	4.21	0.0566	0.63	0.7022
Jmax	52.28	<0.0001	1.29	0.2852	1.08	0.4947
Ci inflection	33.93	<0.0001	1.71	0.2288	1.76	0.2185
Vc,max/Jmax	4.54	0.0044	0.24	0.6269	1.10	0.3946
l	1.29	0.3377	12.65	0.0034	1.76	0.1952
φCO2,max	1.57	0.3001	2.80	0.2969	0.76	0.6334
θ	0.54	0.7676	0.78	0.4060	0.45	0.8222
Cohort 2 (R4, DOY 225)
Asata	66.93	<0.0001	6.14	0.0412	2.88	0.0293
Vc,maxa	76.45	<0.0001	4.65	0.0037	22.07	<0.0001
Jmaxa	24.95	<0.0001	27.36	0.0020	9.11	0.0001
Ci inflectionb	51.68	<0.0001	0.01	0.9196	0.77	0.5876
Vc,max/Jmaxb	13.52	<0.0001	1.25	0.3056	0.88	0.5163
lb	13.23	<0.0001	1.69	0.2419	0.11	0.9884
φCO2,maxa	29.25	<0.0001	2.61	0.2221	8.62	0.0005
θb	2.71	0.0606	0.05	0.8279	2.04	0.1303
Jsatb	19.73	<0.0001	2.94	0.1370	1.15	0.3541
φPSII,max,lb	6.38	0.0014	0.17	0.6854	0.25	0.9332
qPb	7.94	<0.0001	1.62	0.2114	2.36	0.0613
/b	5.13	0.0028	0.00	0.9777	0.42	0.8270

The F statistic and associated P values were calculated from a repeated measures, mixed model analysis of a randomized complete block design (n = 4).

^aValue of 0 used for elevated [O₃] treatment on DOY = 260, when leaves had senesced.

^bCalculations through day 255 since plants grown in elevated [O₃] did not have leaves.