Table I.

The effects of UV-B exposure during growth on g_s of pea leaves

UVB treatment	Normal Leaf Position
	Adaxial	Abaxial	Total
	mol m−2 s−1
Control	0.484 a	0.520 a	1.000 a
Low	0.435 ab	0.496 a	0.930 ab
Medium	0.371 b	0.482 a	0.859 b
High	0.082 c	0.319 b	0.401 c
se	0.020	0.024	0.036

	Leaves Inverted
	Adaxial inverted	Abaxial inverted	Total
Control	0.081 a	0.770 a	0.851 a
Low	0.120 ab	0.666 ab	0.786 ab
Medium	0.130 b	0.577 b	0.709 b
High	0.036 c	0.340 c	0.376 c
se	0.012	0.029	0.034

Results averaged over 9 or 10 d after growth from seed for 21 d either without UV-B radiation (control), or with 0.21 (low), 0.30 (medium), or 0.63 (high) W m⁻² UV-B. Total g_s is the sum of abaxial and adaxial g_s. Means and pooled se for each UVB treatment were calculated from separate ANOVA for each parameter with data from single leaves on six plants in each treatment, with leaves in the normal position (average over 10 d) or leaves inverted after the 1st d of measurement (average over 9 d). Means within the same part of a column (either normal or inverted) followed by same letter are not significantly different (P > 0.05).