Abstract:

【Objective】 Changes in photosynthesis in Vitis vinifera L. cv. Cabernet Sauvignon exposed to high temperature for extended periods and following recovery were investigated to reveal the mechanism of inhibition and recovery of photosynthesis. 【Method】 Two years old Cabernet Sauvignon grapevines were treated for 6 d at high temperature (40℃ from 9:30 to 15:30 and 30℃ during the rest of each day) and then at the same temperatures as the controls. The controls were treated at 30℃ from 6:30 to18:30 and 20℃ during the remainder of each day. Gas exchange and chlorophyll fluorescence parameters were measured before and during high temperature and following recovery. 【Result】 With heat stress, net photosynthetic rate (Pn), stomatal conductance (Gs), the actual PSⅡ efficiency (ΦPSII), the photochemical quenching coefficient (qP), and amount of active PSⅡ RCs per CS (RC/CSo) decreased, intercellular CO2 concentration (Ci), non-photochemical quenching (NPQ), and the damage of oxygen evolving complex indicated by WK, the probability that a trapped exciton moves an electron into the electron transport chain beyond QA- (ψEo) increased. When the grapevines recovered for 1 d from heat stress, the values of these parameters were similar to those in the controls. 【Conclusion】 Pn was decreased by heat stress at 40℃, but recovered to the control level after 1 d. The decrease in Pn were not due to stomatal limitations, but were associated with the donor side and reactive center of PSⅡ. The increase in Pn should be associated with the above all factors.

Key words: Vitis vinifera L.')">Vitis vinifera L., high temperature, recovery, photosynthesis, PSⅡ