Similar to A, CO2 significantly enhanced WUE of oil palm
seedlings (Fig. 8). In week 9 after exposure, 800 and
1,200 lmol/mol CO2 enrichment treatments significantly
(P B 0.01) recorded higher WUE compared to control with
former treatment registering a onefold (8.36 vs 4.14) higher
value. However, there was no clear difference existed
between the two elevated CO2 treatments. By the end of the
experiment (week 15), WUE had slightly decreased in all
treatments although WUE of seedlings exposed to 800 and
1,200 lmol/mol was still higher than the control by fourand
sevenfold, respectively. A very obvious difference was
also noted for WUE between the two CO2 treatments