2.7 Image analysis and statistics
The transverse areas of the leaf vascular tissues were manually outlined, individual tube number counts and length/width measurements evaluated on images with the Image J 1.51d software (National Institutes of Health, Bethesda, MD, USA). Individual images from stem cross sections were aligned and merged into a composite image with the Photoshop software (Adobe Systems, Newton, MA, USA).
Averages from geometrical evaluations were compared using a one-way ANOVA and the post hoc Tukey test at a p <0.05, using the SPSS software for statistics.