Frequently Asked Questions
What are we measuring here?
Photosynq is a platform to help you identifying plant phenotypes. Our standard measurement protocol will collect the following parameters*:
|Parameter||What does it mean?|
|PAR||Photosynthetically active radiation. Fraction of the incoming light (400 nm to 700 nm) which can be utilized to drive photosynthesis|
|temperature||Ambient temperature in degree Celsius (°C)|
|humidity||Relative humidity in percent (%)|
|pressure||Atmospheric pressure (mbar) - This value is not corrected to sea level as found in weather reports|
|contactless_temp||Surface temperature in degree Celsius (°C)|
|SPAD||A measure of leaf “greenness”. This measurement is correlated with relative chlorophyll content. Also, SPAD is often correlated with leaf nitrogen levels|
|Phi2||Quantum yield of Photosystem II. This measurement is essentially the percentage of incoming light (excited electrons) that go into Photosystem II. Photosystem II is where most light energy is converted into food.|
|LEF||Linear Electron Flux. The total flow of electrons from antennae complexes (where light is captured) into Photosystem II, taking the leaf absorptivity into account. Calculated as LEF = Phi2 x PAR x 0.42|
|Fm||Maximum variable fluorescence|
|F0||Minimum variable fluorescence|
|FmPrime||Maximum variable fluorescence at steady-state conditions|
|Fs||Variable fluorescence at steady-state conditions|
|F0Prime||Minimum variable fluorescence during dark phase after steady-state|
|NPQt||Estimate of non-photochemical quenching. The amount of incoming light that is regulated away from photosynthetic processes in order to reduce damage to the plant.|
|PhiNPQ||Ratio of incoming light that goes towards non-photochemical quenching. The plant regulating excess energy in such a way as too reduce damage to the plant.|
|PhiNO||Ratio of incoming light that is lost via non-regulated processes. PhiNO is the combination of a number of unregulated processes whose by-products can inhibit photosynthesis or be harmful to the plant.|
|qL||Fraction of Photosystem II centers which are in the open state|
|PMF||Proton Motive Force - We can estimate PMF by measuring the electrochromic shift (ECS). The energy (ATP) produced by the flow of protons (H+) out of the thylakoid membrane.|
|compass||Cardinal direction in degrees from North|
|compass_direction||Abbreviated cardinal direction (e.g. NW - North West)|
|angle||Cardinal direction in degrees from North|
|angle_direction||Abbreviated cardinal direction (e.g. NW - North West)|
|pitch||Pitch is the angle the instrument is held along the short axis|
|roll||Roll is the angle the instrument is held along the long axis|
*Some of the parameters are not available for the beta version of the MultispeQ
Where can I find more information?
Baker, N. R. (2008). Chlorophyll fluorescence: a probe of photosynthesis in vivo. Annu. Rev. Plant Biol. 59, 89–113. doi:10.1146/annurev.arplant.59.032607.092759.
Kramer, D. M., Cruz, J. A., and Kanazawa, A. (2003). Balancing the central roles of the thylakoid proton gradient. Trends Plant Sci. 8, 27–32. doi:10.1016/S1360-1385(02)00010-9.
Kramer, D. M., and Evans, J. R. (2011). The importance of energy balance in improving photosynthetic productivity. Plant Physiol. 155, 70–8. doi:10.1104/pp.110.166652.
Cruz, J. A., Savage, L. J., Zegarac, R., Hall, C. C., Satoh-Cruz, M., Davis, G. A., et al. (2016). Dynamic Environmental Photosynthetic Imaging Reveals Emergent Phenotypes. Cell Syst. 2, 365–377. doi:10.1016/j.cels.2016.06.001.
Kuhlgert, S., Austic, G., Zegarac, R. Osei-Bonsu, I.,Hoh, D., Chilvers, M. I., et al. (2016). MultispeQ Beta: a tool for large-scale plant phenotyping connected to the open PhotosynQ network. R. Soc. Open Sci. 3, 160592. doi:10.1098/rsos.160592.
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 Environ. 40(8), 1243–1255. doi:10.1111/pce.12924