Dear Colleague, you could think of an experiment where you measure control and stressed plants during several days, weeks, from zero stress plants, gradually increasing stress in the treatment and then induce recovering back until both groups , control and treatment, show similar ojip curves. I guesd a better strategy will be using genetic modified plants (mutant) that are not able to express photophosphorylation. and then apply your stress type treatment and check for ojip differences in your control and treatment plants. Also, a good guess may come from math modeling, in silico ojip curves using a holiistic model that include photophosphorylation in it.

Schansker, Toth & Strasser have published a series of papers about the meaning of the j-i and i-p intervals... however, that controversial subject is still topic of hot academic debate. Good luck!

Dear Colleague, you could think of an experiment where you measure control and stressed plants during several days, weeks, from zero stress plants, gradually increasing stress in the treatment and then induce recovering back until both groups , control and treatment, show similar ojip curves. I guesd a better strategy will be using genetic modified plants (mutant) that are not able to express photophosphorylation. and then apply your stress type treatment and check for ojip differences in your control and treatment plants. Also, a good guess may come from math modeling, in silico ojip curves using a holiistic model that include photophosphorylation in it.

Schansker, Toth & Strasser have published a series of papers about the meaning of the j-i and i-p intervals... however, that controversial subject is still topic of hot academic debate. Good luck!

Dear Prof. Rodriguez,

Thanks a lot for your valuable inputs. We have been collaborating with Prof. Reto J Strasser and Prof. Govindjee and both have been my excellent mentors in the area of fluorescence kinetics vis-a-vis photosynthetic events (in particular photosynthetic electron transport). Both have taught me extremely well regarding the meaning of O-J, J-I and I-P steps, but as you have correctly pointed out, it is indeed a controvercial and complex subject area. That is the precise reason, why I want to educate myself further in this hot field of photosynthetic research through range of experts and colleagues in this subject area. Somehow, we missed to evaluate if there is any link/relationship between OJIP fluorescence kinetics and cyclic photophosphorylation. We have independently recorded increase in cyclic photophosphorylation in plants exposed to osmotic (salt and/or drought) stress as well as stress caused by few heavy metals. It is relatively simple to explain alterations in Fo, Fm or Fv, [based on O and P]. Many a times it is difficult to authentically predict and explain reason behind alteration in J-I and I-P rise.

best regards

Dear Prof. Pardha-Saradhi,

As far as I know, cyclic photophosphorylation (CPP) occurs mostly in cyanobacteria and green algae... in most cases, higher plants exhibits non-cyclic CPP... and this is a PSI related phenomenae... which was not measurable using ojip curves... There is a new MPEA multisignal system, able to measure PSI activity and delayed fluorescence activity as well. You could see with prof Strasser to get some insights into this relatively new (since 2008) technique.

A good math modeling of PSII-PSI activity coupled to cyt b6f ferredoxyn and ATPase activity could eventually reveal a possible connection between PSI and PSII activity (ojip curves)... Remember, ojip is happening in thr first second while Non-cyclic photophosphorylation (NADP+ and ATP activity) occurs in the several minutes range...

I am partially agreeing with Ronald Maldonado Rodriguez . It also occurs in higher plants under stress conditions. To measure PSI and PSII activities at sometime, Its better to use Dual PAM 100 (Heinz Walz, Effeltrich, Germany) which measures CEF, Y(CEF), Y(NO), Y(ND) and Y(NA). I am a beginner with Dual PAM, still I can tell that it can provide lot of information reading the PSI which is not possible with Chl fluorescence alone.

Dear Prof. Rodriguez,

Thank you very much for your views. I agree, but cyclic photophosphorylation occurs in higher plants as well. We had recorded the same, while we were collaborating with Late Prof. Prasanna Mohanty.

Yes, OJIP kinetics are recorded very rapidly (within a second or so) and cyclic flow of electrons (linked with enhanced build up of H+ gradient i.e. additional gradient and hence additional ATP generation) depends on several factors and would take longer time. Now, I realized that immediately after dark adaptation - OJIP kinetics are recorded within a second and hence, at this stage there would not be any photophosphorylation. Thanks for your thought provoking answer.