Table III.

Analysis of the response of A to c_i in pea leaves before or after exposure to high-UV B (0.63 W m⁻²) irradiation for 14 h

Parameter	Control				+UV-B
	0 h	14 h	P	Percentage change	0 h	14 h	P	Percentage change	Pdiff
Amax (μmol m−2 s−1)	35.8  ± 1.4	27.8  ± 2.5	0.033	−22	25.6  ± 5.6	16.3  ± 3.0	0.179	−28	NS
Asat (μmol m−2 s−1)	23.3  ± 1.0	16.9  ± 1.5	0.004	−28	18.2  ± 2.4	7.7  ± 1.4	0.054	−55	0.050
Vc,max (μmol m−2 s−1)	99.5  ± 7.1	66.1  ± 5.8	0.011	−34	70.1  ± 10.6	42.2  ± 11.1	0.160	−33	NS
Jmax (μmol m−2 s−1)	238  ± 11	159  ± 19	0.002	−33	173  ± 37	99  ± 28	0.169	−34	NS
l (%)	11.1  ± 1.4	12.4  ± 1.2	0.050	+1	12.1  ± 2.5	19.8  ± 1.9	0.108	+8	0.110

Parameters estimated from analysis were: A_max, A_sat, V_c,max, J_max, and l. During measurement PPFD was 1200 μmol m⁻² s⁻¹, leaf temperature was 25°C ± 0.5°C, and VPD = 1.5 kPa. Values shown are means ± 1 se of three replicates. P, Probability for observed differences between 0- and 14-h measurements for each treatment, calculated from paired, one-tailed t test; Pdiff, probability for difference between treatments in percentage change, calculated from one-tailed t test. NS, Pdiff > 0.20.