Please see the our paper in Royal Society Open Science for a detailed breakdown of our chlorophyll fluorescence measurements (Fs, Fm, and Fo).

http://rsos.royalsocietypublishing.org/content/3/10/160592

Hi Dan! I also wonder how it measures Fm in the short time (without dark adaptation)? Your macro seems to apply a coefficient (4.88) for the calculation. If so, where does the coefficient come from?

Jun, We have a paper coming out on July 17 that will provide a very detailed description about how we derived the calculations. Here is the citation for the paper, I hope that paper will answer your questions.

Tietz S., Hall C.C., Cruz J.A. & Kramer D.M. (2017) NPQ(T): a chlorophyll fluorescence parameter for rapid estimation and imaging of non-photochemical quenching of excitons in photosystem II associated antenna complexes. Plant, Cell and Environment, in press.

Hey, Dan. What do you mean "We have found ΦNO and ΦNPQ to be positive indicators of crop status (see poster by TerAvest et al.)" (file:///C:/Users/HzA/Downloads/Poster%204%20Zambia_Isaac_fin.pdf). Is it mean that increase ΦNO and ΦNPQ no good for yield and it is the indicator of the stress? Am I right?

Andriy,

We have found in numerous projects that PhiNPQ and PhiNO are both good indicators of stress and we have found both positive and negative correlations between these 2 parameters with eventual crop yield. The direction of the correlation between the parameters and stress or yield often depends on the situation.

For example, in an experiment in which plants are intentionally stressed (inoculated with a pathogen, grown under drought stress, etc) an elevated PhiNPQ tends to denote an increased ability by the plant to respond to stress and self regulate. In these cases, we have found a positive relationship between PhiNPQ and yield or the ability to over come stress. Conversely, on some on-farm studies, where collaborators have been trying to evaluate the adaptability of plants to local conditions, an elevated PhiNPQ may denote that a plant is more stressed than other plants in that environment, and therefore PhiNPQ is negatively correlated with crop yield or the plants adaptability.

These are just a couple of examples, and the results may differ in other crop, regions, experiments, etc.

Yes, I understand. It's not so simple and direct. But often Many farmers, with whom I spoke, ask immediately after the measurement: "Well, the plants are in good condition or not. It's good or bad et al") Wishing to get a quick and unprompted result on the spot.

Thank you for your reply. I enjoy getteing used to this instrument very much!

Hey, guys! Question for all who work with wheat. Maybe somebody has experience work with wheat and know what kind of the parameters PhiNO or PhiNPQ more often correlated with crop yield or stress.

We have just published a new manuscript that explains in detail how he measure photosynthetic parameters. Check it out!

Nice paper! Will the "Leaf Photosynthesis MultispeQ Vx " protocol be updated to calculate the new parameters [PhiNO(T),PhiNPQ(T), qE(T), and qI(T)]? These parameters can be calculated from a downloaded .csv file, but it would be nice if the protocol did it on the front end.