Exogenously spermidine alleviates damage from drought stress in the photosystem II of tall fescue

Drought stress is one of the major limiting factors to crop productivity around globe. It has been well documented that spermidine (Spd) plays an important key role in plant growth and development, especially defense response stress. The objective this study was explore effect Spd on protecting photosynthetic apparatus tall fescue under drought application significantly improved OJIP (fluorescence rise kinetics O-J-I-P) curve compared non-Spd during drought. Exogenous exhibited higher FJ value at J-step (2 ms) OJIP) FP (maximal recorded fluorescence intensity, peak P than application. Moreover, normalised total complementary area (Sm) number QA (primary quinone acceptor PS II) reduction events (N) reduced after In terms quantum yields efficiencies specific energy fluxes, exogenous notably decreased values efficiency electron transfer from QB (secondary PSI acceptors (δR0), absorption flux per RC (ABS/RC) trapping (TR0/RC) without watering. All above suggested facilitated system These observations involved transport capacity photosystem II assist understanding better protective