Figure 4.

Enhanced cytokinin biosynthesis in the roots delays leaf senescence in grafted plants. Picture of the homografted M82/M82 (left) and heterografted M82 scions over MDK:IPT rootstocks (right; A), photosynthetic rate (B), stomatal conductance (C), and the rate of photosynthesis per internal CO₂ concentration (Ci; D) of remaining tomato leaves after partial defoliation of the other leaves (empty symbols). Defoliation was performed on either homografted (circles) or heterografted (squares) plants grown in a temperature-controlled greenhouse (25°C/18°C day/night). Dashed lines and empty symbols represent partially defoliated plants; solid lines and full symbols represent nondefoliated plants. Student’s t-test was used to compare mean values of six plants. Different letters indicate significant differences at p < 0.05.