Influence of hyperthermal stress on the functional state of persimmon (Diospyros kaki Thunb.) leaf apparatus

The article presents the results of evaluation of heat resistance of leaves of persimmon (Diospyros kaki Thunb.) by changing the kinetics of fluorescence induction of chlorophyll a. For comparison, we took five cultivars: ‘Zolotistaya’, ‘Mechta’, ‘Rosseyanka’, ‘Hyakume’, and ‘Yuzhnaya Krasavitsa’. For temperature effects, we used two levels of elevated temperature: 35 and 45°C. Short-term exposure to 35°C did not lead to any significant physiological changes (i.e., variation of the photoinduction curve and calculated coefficients did not differ from the control). The longer exposure to high temperature (45°C during 4 h) led to photo-inhibition, which is associated with a decrease in the activity of the reaction center Photosystem II (PS II). In treatments where hyperthermia was combined with hydration, we observed a decrease in the coefficient of variable fluorescence (F_v = F_m-F₀) by 66.5%, the maximum photochemical quantum yield of PS II (F_v/F_m) at 35.8%, photosynthetic activity (PA = (F_m-F_t)/F_m) at 18.7%, fluorescence decay coefficient (F_m/F_t) at 26.4% and effective photochemical quantum yield PS II (Y(II) = (F_mRSQUO-F_t)/F_m) at 54.7%. In treatments where leaves were dehydrated, there was a more significant decrease in the effective photochemical quantum yield of PS II (by 79.4%). Thus, cultivars with high water-holding capacity and good turgor recovery ability are better adapted to high-temperature stress.

I International Symposium on Botanical Gardens and Landscapes

S. Khokhlov, S. Tsiupka, V. Melnikov, V.A. Brailko

hyperthermal stress, fluorescence, chlorophyll, heat resistance, water-holding capacity, persimmon

https://doi.org/10.17660/ActaHortic.2020.1298.83