Finally, …an inexpensive light adapted Y(II) & ETR measuring instrument based on hard science. Y(II) or DF/FM ’ or (FM’ – FS ) / FM’) is a time tested light adapted parameter that is more sensitive to more types of plant stress than FV/FM. A survey of existing research strongly supports this statement. While FV/FM is an excellent way to test for many kinds of plant stress, and the health of Photosystem II, Quantum Yield of PSII or Y(II) is a test that allows the measurement of the efficiency of photosystem II under actual light adapted environmental and physiological conditions. The new Y(II) meter includes: 1. Y(II) measurement & ETR measurement corrected for leaf absorptance. 2. Leaf absorptance measurement including leaf transmittance using RGB sensors. (It may be used on larger Arabidopsis leaves.) 3. 4. 5. 6. PAR measurement (photosynthetically active radiation near the leaf) Leaf temperature measurement averaged over a large area. FM’ correction option at high actinic light levels, according to Loriaux 2013. A long term automated “monitor fluorometer mode” that allows measurement day and night. Useful for laboratory work. There are holes in the base of the chamber to allow photosynthesis. 7. Relative humidity sensor 8 Winn Avenue Hudson, NH 03051, USA 603-883-4400 ww

Y(II) meter was designed to provide an inexpensive way to measure Y(II) and to make it available to more people that need it. Opti-Sciences developed a system that does not require expensive fiber optics, but still follows the proven methods needed for reliable plant stress measurement. Y(II) is measured from the top of the leaf along with PAR or photosynthetically active radiation. Furthermore, leaf temperature is measured from the bottom over a large area, allowing a more reliable value. Leaf absorptance is normally measured using an integrating sphere; however, this new instrument provides...

Innovative Y(II) meter design Technology Advances The Opti-Science Y(II) meter - PAR Clip was created to improve upon previous industry designs and maintain an affordable price. By developing a bottom opening design, this new model prevents inappropriate opening when measuring leaves above the operators head, or when mounted on a tripod that occurs with some industry designs. As a result, the Opti-Science Y(II) meter allows one handed operation, and eliminates two handed operation. This PAR light sensor is positioned to allow measurement of ambient PAR very close to the leaf and at the same angle...

based on Loriaux (2006), & Loriaux, (2013) Saturation pulses used with modulated fluorometers are designed to close all PSII reaction centers. The maximum fluorescence intensity value, of the saturation flash, FM’, is used in most measurements including, quantum yield of PSII MPSII (also called Y(II) or )F /FM’ ), J (or ETR), and in all quenching protocol parameters. While it is possible to reduce or close all reaction centers in a properly dark adapted sample, with a relatively low amount of light, it has been found that in light adapted samples, with a high actinic light history, complete closure...

Attention to Detail Based on hard science. The original light adapted chlorophyll fluorescence test, developed by Bernard Genty, is designed to correlate with photosynthesis gas exchange measurements (Genty 1989, 1990). It provides a measurement of the light adapted, light reaction of photosynthesis under different conditions, and it can be more sensitive than FV/FM for some types of plant stress. (See the section on plant stress measurement). For reliable measurement, samples must be at steady state photosynthesis, and measurement of Y(II) and PAR should be from the same side of the leaf as...

Attention to Detail Data Management The Y(II) meter provides a two gigabytes of non-volatile flash memory designed to prevent data loss due to power interruption. USB A USB cable is provided on the back of the Y(II) meter. When connected to a PC, the Y(II) meter becomes a hard drive for a computer, allowing the transfer of data measuring files, and software upgrades. No special software is required. Files may be opened with Excel , or any other program that takes comma delineated information. Any USB battery may be used. The one shown below will provide more than 8 hours of use without recharging,...

New - Monitor Mode This measuring mode is designed to measure leaves, day and night, over long periods of time, during growth periods, or even season long periods. Due to its design, it can be used in growth chambers or for laboratory use, with controlled lighting. While the Y(II) meter is perfect for field use, the monitor mode is not designed for field use, due the edge effects that can occur with a smaller measuring aperture when the sun is low in the sky. Y(II) = FV/FM in the dark at steady state. Furthermore, this data can be used to calculate NPQ and other quenching parameters. The times...

Comparison of Y(II) and FV/FM for stress measurement For more detailed information request the Opti-Sciences Desktop Stress Guide. Stress Drought Stress Y(II) Is not sensitive to drought stress in C3 plants until the drought is severe due to photorespiration (Flexas 1999, 2000). Not sensitive to early or moderate water stress in most plants (Bukhov & Carpentier 2004) (Zivcak M., Brestic M, Olsovska K. Slamka P. 2008) The only reliable fluorescence test is using the Burke assay with Y(II). It is very sensitive to very early water stress in C3 plants. (Burke 2007, 2010) Drought Stress Drought Stress...

Nitrogen Stress Y(II) can be used for early nitrogen stress by adding intense light (Cheng 2001). It is common to use chlorophyll content meters for nitrogen stress. FV/FM is not sensitive to nitrogen stress until very low levels are reached. (Baker 2004) It is common to use chlorophyll content meters for nitrogen stress Light stress Y(II) can also be used for light stress in steady state sensitive to light stress. (Cavender-Bares & Bazzaz 2004) FV/FM can be used to detect light stress (Adams & Demming-Adams 2004) Heat stress Y(II) can also be used for moderate heat stress from 35oC and higher...