Mészáros, IlonaAmri, RajaKoson, Pattanawut2025-06-162025-06-162025https://hdl.handle.net/2437/391856Abscisic acid (ABA) is a phytohormone involved in plant stress responses, developmental regulation, and dormancy induction. In this study we investigated the physiological and developmental responses of four clones of Spirodela polyrhiza (Sp1, Sp2, Sp7, and Sp8) to exogenous ABA. We assessed the effects of ABA (0.5 µM) on the growth and photosynthetic activity of clones in synthetic growth medium over a 7-day period by measuring RGR, turion yield and chlorophyll fluorescence parameters Fv/Fm, Fv/F0, and Fm/F0. RGR and turion yield data highlights the diverse responses to ABA among S. polyrhiza clones. Clone Sp8 and Sp2 showed the higher RGR values, but they gave respectively the lowest average percentage reduction of RGR parameters compared to Sp1 and Sp7. Clone Sp2, followed by Sp1 emerged as a particularly promising candidate for further study due to its stable growth and moderate turion formation under stress. These observations underscore the complexity of ABA-mediated regulation in aquatic plants and reinforce the need for clone-specific assessments in ecophysiological and applied research contexts. 0.5 µM ABA treatment rapidly increased photosystem II activity in all four duckweed clones, especially Fm/F0 and Fv/F0 ratios showed great increases by DAY 3. Then chlorophyll fluorescence parameters remained approximately at the same level by DAY 7 in most clones. The potential PSII efficiency (Fv/Fm) increased more slightly, confirming also efficient photoprotective capacity in the presence of ABA. The turions harvested on the DAY 7 from the ABA-treated cultures all showed low, almost identical fluorescence parameter values in the cultures of all clones, indicating that the clones down-regulate the photochemical activity and the overall photosynthesis performance in order to achieve dormancy. Our results pointed to that among the chlorophyll fluorescence parameters Fm/F0 and Fv/F0 are the more sensitive indicators of early ABA effects on studied clones than Fv/Fm.26enABA, Duckweed, TurionsBiology::BotanyHozzáférhető a 2022 decemberi felsőoktatási törvénymódosítás értelmében.