Wojciech Bąba1, Agnieszka Kompała-Bąba2, Jolanta Luźniak1 and Robert Hanczaruk2
1Department of Plant Ecology, Institute of Botany, Jagiellonian University, Gronostajowa 3, 30-387 Kraków, Poland
2Department of Botany and Nature Protection, University of Silesia in Katowice, Jagiellońska 28, 40–032, Katowice, Poland
Grass-leaved goldenrod, Euthamia graminifolia (L.) Nutt., is an invasive neophyte in Poland which mainly colonizes seminatural wet habitats (e.g. moist meadows of the order Molinetalia, marshes of the Caricion davallianae allianceand banks of watercourses). Moreover, it expands to more dry habitats such as segetal and ruderal habitats (e.g. sand-pits, quarries, railway embankments, abandoned lands and pine plantations).
After the colonization of novel habitats, photosynthesis is a process central to the plants resistance to different stresses, ability of spreading and competition. As such, studies on acclimatization of photosynthetic machinery are of prime importance. In this work, we study the acclimatization potential of photosynthetic apparatus to drought conditions with use of chlorophyll fluorescence, emitted by a chlorophyll a molecule. Using pot experiments, we grew 400 Euthamia specimens in mixture potting compost and sand under a light intensity of ca. 450-500 PAR photons m–2 s–1, day/night period 12/12 hours. Half of the individulals were fully watered (FW) to 80-90 RWC (%), while the rest underwent simulated drought stress (DRY, 30-40 RWC).
Changes occurring in the photosynthetic apparatus related to drought stress are realized, among others, as a significant decrease of maximum quantum yield of PSII photochemistry (Fv/FM) and in the performance potential for conserving the energy absorbed by PSII photons until the reduction of PSI end acceptors (PITOT). Moreover, we found the changes in antenna organization in DRY plant: an ungrouping of the PS2 antenna complexes and a suppression of the Oxygen Evolving System while in the FW the effects are opposite. We can speculate, that the Euthamia photosynthetic apparatus strongly (and negatively) responds to high intensity drought stress. Our results are also confirmed by a decrease in leaf dry mass by a factor 0.5.