FIGURE 4 Linear regression analysis showing the relationship
between RCS and root growth, root metabolic costs, and aboveground
growth under drought stress. (A) Total root length, (B) root dry weight,
(C) root tissue density, (D) root respiration at 6 cm from the root tip,
(E) root respiration at 9 cm from the root tip, (F) root respiration at
12 cm from the root tip, (G) leaf water potential, (H) leaf relative
water content, and (I) the ratio of variable to maximum fluorescence
(F v/F m ).