Figure 7.

Light Is Required at Dawn to Trigger Leaf Growth.

(A) Leaf elongation rate of leaves 1 and 2 in long day (L/D, black line, n_leaf = 27) and in +3 h prolonged night period after dawn (L/D+3; red line n_leaf = 27).

(B) Leaf elongation rate in L/D (black line) and in +3 h prolonged night period before dusk (L/+3D; blue line, n_leaf = 54).

(C) Leaf elongation rate and leaf elevation angle of leaves 1 and 2 where night was shortened before dawn by −3 h (L/-3D; green line, n_leaf = 35; L/D control; black line, n_leaf = 42). Col-0 plants were grown for 14 d in standard L/D (16/8) conditions before measurement; vertical gray bars represent true night periods; vertical red/blue bars indicate prolonged night periods ([A] and [B]) and vertical hatched green bar shortened night period (C). Leaf elongation rate was computed as mean moving average (3 h) of individual curves. The opaque band around the mean lines is the 95% confidence interval of mean estimate, and n_leaf = number of leaves. Day 1 of the experiment represents the first day when the plants were subjected to an abrupt change in night length. l_tip was used to compute the graphs.