Free Access

Table II

Gas exchange measurements in two contrasting P. cathayana populations exposed to different UV-B levels under well-watered or drought-stressed conditions.

Population Treatment A (μmol m−2 s−1) gs (μmol m−2 s−1) E (mmol m−2 s−1) PNUE (μmol g−1 N s−1)
JZ W 17.23 ± 0.19e 0.75 ± 0.02d 5.75 ± 0.07f 7.32 ± 0.55c
WU 13.78 ± 0.05d 0.64 ± 0.01c 3.88 ± 0.04c 4.91 ± 0.43b
D 12.72 ± 0.11c 0.38 ± 0.05b 2.53 ± 0.20b 4.69 ± 0.11b
DU 5.88 ± 0.28a 0.09 ± 0.00a 0.93 ± 0.04a 2.65 ± 0.36a
DT W 23.35 ± 0.33g 0.82 ± 0.00e 5.78 ± 0.05f 13.17 ± 0.95c
WU 21.55 ± 0.07f 0.60 ± 0.01c 5.00 ± 0.04e 9.68 ± 0.22b
D 21.3 ± 0.21f 0.64 ± 0.02c 4.13 ± 0.07d 9.76 ± 0.34b
DU 8.15 ± 0.29b 0.13 ± 0.01a 1.16 ± 0.06a 7.61 ± 0.82a
P(P) 0.000 0.000 0.000 0.000
P(D) 0.000 0.000 0.000 0.000
P(U) 0.000 0.000 0.000 0.000
P(P×D) 0.001 0.000 0.005 0.173
P(P×U) 0.000 0.000 0.217 0.024
P(D×U) 0.000 0.000 0.000 0.001
P(P×D×U) 0.000 0.069 0.000 0.070

JZ, the low altitude population; DT, the high altitude population. ANOVA: P(P) : population effect; P(D) : drought effect; P(U) : UV-B effect; P(P×D) : population × drought effect; P(P×U) : population × UV-B effect; P(D×U) : drought × UV-B effect; P(P×D×U) : population × drought × UV-B effect. W, well-watered; WU, well-watered+enhanced UV-B radiation condition; D, drought; DU, drought+enhanced UV-B radiation condition. Values followed by the same letter in the same column are not significantly different at the P < 0.05 level according to Duncan’s multiple range test. Values are means± SE, n = 5.