Carbon isotope composition.

Data are reported as the mean ±1 SE (n = 5)
The C isotope composition (‰) of leaf-respired CO2 (δ13CR), leaf soluble carbohydrates (δ13Csugar), leaf starch (δ13Cstarch) and leaf lipids (δ13Clipid) at 8 pm and 4 am, respectively. The carbon isotope composition of leaf bulk tissue (δ13Cbiomass) was measured once at 8 pm. The amplitude of the nighttime variation in δ13CR (Variation in δ13CR) was estimated as δ13CR-8pm—δ13CR-4am. Differences in the δ13CR between the samples collected at 8 pm and 4 am were assessed by One-way analysis of variance (ANOVA) and the P values are presented.