Profile cover photo
Profile photo
Opti Sciences
Measure photosynthesis & plant stress
Measure photosynthesis & plant stress
Opti's posts

There seems to be more interest in photosynthetic induction response because, in many cases, steady state photosynthesis is not always achieved in field plants. Wind, clouds, partial shade, and light flecks, make the study of the initiation of photosynthesis valuable. In a recent paper, no correlation was found between steady state photosynthesis and measuring the results of photosynthetic induction response.

Of course, there are both chlorophyll fluorescent and gas exchange methods for measuring photosynthesis under changing light conditions. Are any of these studies valid without the use of white light?

Contact Opti-Sciences for more information.

Soleh M.A., Tanaka Y., Kim S.Y., Huber S.C. Sakoda K. Shiraiwa T., (2017) Identification of large variation in the photosynthetic induction response among 37 soybean [Glycine max (L.) Merr.] genotypes that is not correlated with steady-state photosynthetic capacity, Photosynthesis Research, March 2017, Volume 131, Issue 3, pp305-315

Progress in drought stress -

Researchers at the University of Illinois have used x-ray diffraction and supercomputer modeling of “molecular dynamic simulations”, to show the molecular details of how the drought stress hormone ABA (absorbic acid), binds to the plant PYL receptor. After binding, “there is little or no water loss from the plants”. Since most plant drought stress mechanisms are the same, it is hoped that an economical and practical plant spray can be developed to help prevent plant damage, moving forward.

Biophysical Society. "How a plant resists drought." ScienceDaily. ScienceDaily, 14 February 2017. <>.

Post has attachment
New paper investigates insect herbivory in forests. Nitrogen content was estimated using the CCM-200plus. Among other findings, it shows that herbivory is lowest, on upper canopies, when the temperatures are highest. Furthermore, that temperature is the best predictor of herbivory on the layers under study.

Stiegel, S. Entling, M.H. and Mantilla-Contreras, J. (2017) “Reading the Leaves’ Palm: Leaf Traits and Herbivory along the Microclimatic Gradient of Forest Layers”. PLoS ONE 12(1): e0169741. doi:10.1371/journal.pone.0169741.


Post has attachment
Using the ACM 200plus anthocyanin meter to measure anthocyanins in relation to fungal damage

Tellez P., Rojas E., Van Bael S., (2016), Red coloration in young tropical leaves associated with reduced fungal pathogen damage, Biotropica, Volume 48, Issue 2, March 2016, Pages 150–153 DOI: 10.1111/btp.12303


“Chloroplast migration” vs. “acute photoinhibition” and “state transitions”… changes to minimum dark adaptation times and times to reach “steady state”

Until fairly recently, it was thought that the effects of high actinic light levels on chlorophyll fluorescence for intermediate periods of time, in the range of about 7 minutes to 30 minutes, were either due to state transitions, or “acute photoinhibition”. As a result, a minimum dark adaptation time of 20 minutes was required to completely relax state transitions (Theile, Krause & Winter, 1998).

Recent research indicated that the intermediate changes were primarily due to “chloroplast migration” and not due to “acute photoinhibition” and state transitions (Cazzaniga et al., 2013), (Dall’Osta 2014). Chloroplast migration takes between 20 to 30 minutes to fully adjust or fully relax. In some mutants, it has taken up to 35 minutes. As a result, the minimum dark adaptation times, and the times to reach steady state photosynthesis should probably be extended to 30 minutes. Chloroplast migration can be responsible for up to 30% on NPQ or non-photochemical quenching. It’s designation is qM. Furthermore, it only happens under intense blue or white light and not red light.

Chronic photo-inhibition is different than “acute photoinhibition". Chronic photoinhibition is caused by several hours of high light exposure, and starts to relax or repair at about 40 minutes and may take 30 to 60 hours to fully relax or repair under dark adaptation (Lichtenthaler & Babani, 2004), (Theile, Krause & Winter 1998).

Important note: Because belief in dark adaption times varies with education, it is recommended that before designing an experiment, one should contact potential publication reviewers before deciding on dark adaptation times.

See the “application note on qM chloroplast migration” for more details. Also, see the application notes on quenching, and dark adaption.

A new form of “cooperative photosynthesis” has been discovered.

Two bacterium: P. aestaurii and G. sulfurreducens can work together to generate a type of “anaerobic photosynthesis” never seen before. P. aestaurii accepts electrons in the presence of sulfur or hydrogen sulfide to photosynthesize in the presence of sunlight. G. sulfurreducens consumes organic matter, gives off CO2 and can provide electrons that can be used by P. aestaurii.

Washington State University. "Unique microbial photosynthesis discovered: Finding could be used for waste treatment, energy." ScienceDaily. ScienceDaily, 9 January 2017. <>.

Post has attachment
In a last-minute effort, the US Senate and House fund the US government through April 28 2017 before adjourning for the holidays.

However, a bill designed to increase National Science Foundation funding and National Institute of Standards and Technology funding did not pass.

Agency funding was frozen through April of 2017 in a separate effort.

Source: the ASA. CSSA, SSSA newsletter

Post has attachment
Researchers at the University of Nebraska measured chlorophyll content in corn and weeds using the CCM-300 chlorophyll content meter.

The paper, listed below, seeks to determine the effect of light quality on corn growth under the influence of weed growth and nitrogen levels in corn. Both nitrogen deficient corn, and well fertilized corn samples, with high chlorophyll content, were tested. The researchers chose to measure the fifth leaf from the top, take six measurements on each leaf, and average the values.

The CCM-300 uses the Gitelson 1999 ratio fluorescence measuring method, that provides more reliable measurements than leaf absorption measuring methods, on plants with high chlorophyll content levels that are well fertilized (Gitelson 1999). Using leaf light absorption chlorophyll content measuring methods, correlation to chemical chlorophyll content testing starts to fall off above 450 mg m2 (Gitelson 1999). In the CCM-300 method, using ratio fluorescence, correlation to chemical testing starts to fall off above 675 mg m2 (Gitelson 1999).

Butts T.R., Miller J., Pruitt D., Vieira B.C., Oliveira M.C., Ramirez S., Lindquist J.L. (2016), Light Quality Effect on Corn Growth as Influenced by Weed Species and Nitrogen Rate, Journal of Agricultural Science; Vol. 9, No. 1; 2017 ISSN 1916-9752 E-ISSN 1916-9760 Published by Canadian Center of Science and Education December 15, 2016 doi:10.5539/jas.v9n1p15

Gitelson A. A., Buschmann C., Lichtenthaler H. K. (1999) “The Chlorophyll Fluorescence Ratio F735/F700 as an Accurate Measure of Chlorophyll Content in Plants” Remote Sens. Enviro. 69:296- 302 (1999)


Post has attachment
Using Y(II) and Fv/Fm measurements on an OS5p+ chlorophyll fluorometer to determine alkali stress.

Zhang, A., Zang, W., Zhang, X., Ma Y., Yan X., Pang Q., (2016) Global proteomic mapping of alkali stress regulated molecular networks in Helianthus tuberosus L. , Plant and Soil, December 2016, Volume 409, Issue 1, pp 175–202, (doi:10.1007/s11104-016-2945-7)


Post has attachment
Chlorophyll Content meters work better on nitrogen and sulfur stress measurement than Fv/FM, Y(II) or OJIP.

See the application note on nutrient plant stress measurement
2 Photos - View album
Wait while more posts are being loaded