Rate of local cell production (Number of cells/mm in each cell row of the root meristem). A) Two-day experiment. B) Four-day experiment. Statistically significant differences in cell production (p < 0.05), compared to the control, are indicated with a ‘§’ symbol when compared with the 1 g external control, and with ‘#’ when compared with the 1 g* control. Seedlings grown in the 0 g* tube show consistently higher cell proliferation rates compared with controls.