Figure 1. EBR induced systemic stress tolerance in cucumber plants.

(A) The 5^th leaf of cucumber seedlings corresponding to the local treated leaf at the seven-leaf stage was pretreated with distilled water (DW) or 0.2 µM EBR; 24 h later the upper leaf (6^th) corresponding to the systemic leaf was exposed to 10 µM paraquat (PQ), photographs were taken at 24 h after PQ treatment. (B) The maximal photochemical quantum efficiency of photosystem II (Fv/Fm) was monitored at 24 h after PQ treatment with imaging pulse amplitude modulation (PAM) to assess the changes in tolerance. (C) Fv/Fm measurement of systemic leaves. Data represent the means of five replicates ± SD. Bars sharing the same letters are not significantly different within the treatment (P≤0.05).