†Zmasft had significantly higher E andg s than WT (P < 0.0001). There was a significant interaction between RH and light intensity in that E was higher at both low and high RH compared to low light intensity. At low light intensity, E was significantly lower at 50 % RH than at 80 % RH.
‡Partial volume of leaf total vasculature including all midrib tissue was 0.50 and 0.49 for WT and Zmasft double mutants, respectively, and there was no significant difference between genotypes (P = 0.72). There was a significant interaction between genotype and light intensity (P < 0.05), whereL v was higher in the Zmasft double mutant only under 300 μmol m-2 s-1. There was a significant interaction between RH and light intensity (P < 0.0001), where L v was higher under 300 μmol m-2 s-1 at 50 % RH than at 80 % RH.
§Partial volume of vascular bundles in the leaf (including the bundle sheath) was 0.25 and 0.26 for WT and Zmasftdouble mutants, respectively, and genotypes were not significantly different (P = 0.70). Genotypes were marginally different inL v (P = 0.06). There is a significant interaction between genotype and light intensity (P < 0.05), whereL v under 300 μmol m-2s-1 was higher in the Zmasft double mutant.L v in the xylem Péclet model could not be calculated when ϕx was considered the partial volume of vascular bundle excluding the bundle sheath or xylem in the leaf.
¶Light intensity x Genotype interaction was significant (P < 0.05).
Table 2 . Leaf water isotope parameters for O. sativawild type (Nipponbare), cslf6-1 and cslf6-2 , grown under 1000 and 300 photosynthetic active photon flux density (P, μmol photons m-2 s-1). f swis the proportion of unenriched water in bulk leaf water. Calculation of Lv made by using the partial volume of vascular tissue including the entire midrib as θ x. A two-way ANOVA was performed to test the significance: * P < 0.05, ** P < 0.01, *** P < 0.001. Tukey post hoc test represented when PxG interaction was significant. Values with the same superscripted letters are not significantly different. Growth light condition is represented by P (PAR) and genotype by G.