variety. Over expression of the stress response gene SNAC1 led to reduced water loss, but no significant change in photosynthetic rate. This Canadian team examined the dynamic responses of Stomatal conductance (gs) net photosynthesis (A) to a progressive drought in nine poplar clones with contrasting drought tolerance. gs and A were measured using a photosynthetic system. Plants were either well-watered or drought preconditioned. Researchers at Banaras Hindu University, India, investigated the potential of sewage sludge to be used in agriculture as an alternative disposal technique. Agricultural soil growing rice had sewage sludge added at different rates. Rates of photosynthesis and stomatal conductance of the rice were measured to examine the biochemical and physiological responses of sewage addition. Researchers from Lancaster University, The University of Liverpool, and The University of Essex, UK, measured isoprene emission rates from an oil palm tree. Samples were collected using a photosynthetic system that controlled PAR and leaf temperature (1000 μmol m−2 s−1; 30 °C). It had thought that PAR and temperature are the main controls of isoprene emission from the biosphere. This research showed that isoprene emissions from oil palm tree are under strong circadian control. The ecophysiological diversity and the breeding potential of wild coffee populations in Ethiopia was evaluated as a thesis submitted to The Rheinischen Friedrich-Wilhelms-University of Bonn, Germany. Complementary field and garden studies of populations native to a range of climatic conditions were examined. Plant ecophysiological behavior was assessed by a number of system parameters, including gas exchange, which was measured using a photosynthetic system. A collaborative project between researchers at the University of Cambridge, UK, the Australian Research Council Center of Excellence, and the Australian National University resulted in validation of a model that describes carbon isotope discrimination for crassulacean acid metabolism using Kalanchoe daigremontiana. Instruments of this type can also be used as a standard for plant stress measurement. Difficult to measure types of plant stress such as Cold stress, and water stress can be measured with this type of instrumentation. References External links http://www.ipipotash.org/udocs/CO2_Gas_exchange_parasystems_paper.pdf Plant physiology