Looking at the global demand for feed crops it is predicted to increase almost double by 2050 due to growing world population (Foley et al., 2011). Considering the increase in global temperature and water scarcity, crops in the future need to be more water and nutrient use efficient to sustain food security. Photosynthesis or net canopy CO2 exchange is one of the driving forces of crop yield formation.
Since most commercially available equipment have been designed for single leaf measurements, photosynthesis at a leaf level has been studied more intensively than canopy photosynthesis.
Leaf photosynthesis measurements are often poorly correlated with crop yield, whereas whole plant (canopy) photosynthesis measurements correlate well with crop yield (Kim et al., 2006). Whole canopy measurements bypass the problem of finding a representative leaf and give information about the whole plant physiology and other plant physiological processes. In addition to canopy photosynthesis measurements, non-destructive approaches such as stable isotope measurements via online lasers are excellent tools to study the efficiency in transpiration and photosynthesis in crop plants (Senbayram et al., 2015).
Here we show different applications of the the Thermo Scientific™ Delta Ray™ Isotope Ratio Infrared Spectrometer (IRIS) to investigate processes related to photosynthesis and respiration in various ecosystems on scales ranging from the whole plant to the whole ecosystem.
With the aim to monitor photosynthesis and plant respiration Delta Ray was deployed also in the automated chamber program. Because several plant chambers were measured in sequence, electrical trigger signals allowed synchronizing the Delta Ray with the automated chamber program.
In the field project different locations were monitored by time constructed sequence, allowing system to change to different locations every 30 minutes.
The Delta Ray analyzer can be easily integrated in gas exchange experiments to measure the δ13C and δ18O in CO2 of one or several plant chambers sequentially. This results in a high-resolution dataset of plant gas exchange and its isotopic signature, which allows to identify short-term and long-term changes in plant metabolism.
Detection of explosives is an emerging task for maintaining civil security. Optical methods and especially tunable diode laser spectroscopy are discussed as means for providing fast and reliable data. Selective and sensitive detection is possible in the midinfrared spectral region; however, until recently, small and easy to operate laser sources were not readily available for applications outside the laboratory. The situation changes with the maturation of quantum cascade lasers (QCLs). We present detection methods based on photofragmentation and subsequent midinfrared detection of the fragments for the detection of nitrogen-based explosives. For this type of explosive, the very low vapor pressure makes the use of direct spectroscopic techniques extremely difficult, since the equilibrium concentrations are in the ppb to ppt range. Peroxide-based explosives like triacetone triperoxide possess a much higher vapor pressure, making direct absorption spectroscopy and also a quartz-enhanced photoacoustic spectroscopy sensor possible. The progress and challenges of the application of QCLs, also with respect to interferences with other molecules present, are discussed.
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