Figure 6.

Positions of stimulation, electrical potential, and photosynthesis parameter measurements, and heating in pea plants (A), and procedure for investigating photosystem activities after heating (B). E_L is the electrode connected to the leaf, E_S is the electrode connected to the stem, and E_R is the reference electrode. The distance between E_L and E_S was 3–4 cm. Burning of the tip of the first mature the leaf (with a flame for 3–4 s over an area of about 1 cm²) was used as the external stimulus inducing VP.^8,9 Both leaflets of the second leaf (area marked by the dotted line) were heated in hot water at different times after VP induction. PSI and PSII activities after heating have been indicated using 1-ф_PSI⁰ and ф_PSII⁰.