Fig. 5. (a) Slopes of time (days) vs. chlorophyll concentration (ChlSPAD) linear regression with the intercept fixed at 7 days after water restriction initiation. (b) Slopes of days after tuber initiation onset vs. tuber dry biomass (TB) linear regression. White bars indicate control treatment, and the black bars indicate water restriction treatment. **P < 0.01, *P < 0.05.