Effect of exogenous calcium pretreatment on slow P515 induction transients of tomato seedlings under LNT.

<p>(A) Changes in the P515 signal of slow dark–light–dark induction transients. (B) Two components of the proton motive force (transmembrane potential and proton gradient) derived from the slow dark–light–dark induction transients of the 550 nm to 515 nm signals. The transients were measured after 1 h of dark adaptation. Actinic light (AL; 531 µmol·m⁻²·s⁻¹) was turned on after 30 s and off after 330 s. CK, the plant grown at optimal temperature, and used for control; CaCl₂+LNT, the plant pretreated with CaCl₂ and grown at low night temperature (LNT); H₂O+LNT, the plant pretreated with H₂O and grown at LNT; EGTA+LNT, the plant pretreated with EGTA and grown at LNT. Data are the means of four replicates with standard errors shown by vertical bars. *indicates significant difference (P≤0.05), and **indicates a highly significant difference (P≤0.01). Comparisons between the figures among all treatments under low night temperature are shown in parentheses.