Photosynthesis production measurement methods

A method of detecting herbicides is proposed the photosynthetic herbicides act by binding to Photosystem II (PS II), a multiunit chlorophyll-protein complex which plays a vital role in photosynthesis. The inhibition of PS II causes a reduced photoinduced production of hydrogen peroxide, which can be measured by a chemiluminescence reaction with luminol and the enzyme horseradish peroxidase (HRP). The sensing device proposed combines the production and detection of hydrogen peroxide in a single flow assay by combining all the individual steps in a compact, portable device that utilises micro-fluidic components. 

Chlorophylls occur very frequently in the plant kingdom, they are responsible for the colour of vegetables and some fruits. They also occur in algae and several bacteria. Chlorophylls in plants are photoreceptors and in photosynthesis the presence of a closed circuit of conjugated double bonds allows them to absorb light. Because of their predominant importance as photoreceptors a considerable number of analytical methods have been developed for the separation and quantitative determination. The analytical methods applied for the measurement of chlorophylls and carotenoids in food products have been reviewed previously [273],... 

To sum up, it should be realised that both methods, O2 2md C method, have serious limitations. The C method is certainly the more sensitive one, but from data no respiration can be measured and therefore no net production can be calculated whereas the oxygen method gives a good estimate of assimilation and dissimilation (Golterman, 1975). The question, at one time actively debated, on whether uptake gives a measure of net or gross photosynthesis or some intermediate value, has never been resolved (Bunt, 1975). Mostly the assumption is made that nearly all fixed carbon comes from directly assimilated CO2 (and not partly from older respired carbon) and that the radiocarbon method more or less measures net primary production (De Vooys, 1979). 

Because only primary stages are involved in photosynthesis and respiration (electron carrier chains and some key enzymes in the cofactor exchange reactions), it seems convenient to first formulate a kinetic coupling law related to the specific net oxygen production rate Jo2- Assuming that respiration rates are affected by the radiation field (as confirmed for some micro-algae and reported for experimental measurements by specific analytical methods Joliot, 1966), we can propose a rather symmetrical local law for respiration (this law is related to the already developed approach at the chlo-roplast level in the general form (Pruvost and Comet, 2012)) ... 

Although the technique as described is relatively simple, interpretation of the results is not. Strickland (1960) regrets that initial efforts were directed toward collecting data rather than toward a critical evaluation of the technique. He believed that the evidence to 1960 indicated that the method results in a measure of photosynthesis between net and gross production, but closer to the former. 

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