Effect of (Changes in) Air Humidity on Transpiration and (Adaptation of) Stomatal Closure of Tradescantia Leaves during Water Stress

This paper summarises our recent research on the physiological effects of prolonged high RH during growth on stomatal function and we discuss possibilities that arise from this work for reducing postharvest quality problems in cut flowers. Chlorophyll fluorescence imaging was used to measure stomatal closure in response to desiccation of Tradescantia virginiana leaves grown under high (90%) and moderate (55%) relative humidities, or transferred between these humidities. Stomata of plants transferred from moderate RH conditions to high RH showed the same diminished closure in response to desiccation, as did stomata that developed at high RH. This response was found both when the leaves were either fully expanded or still actively expanding during the moderate RH pre-treatment. However, when leaves were grown in high RH prior to a moderate RH treatment, the reduced stomatal closure response to desiccation was only reversed in leaves (regions) which were still actively expanding during moderate RH treatment. This indicates that with respect to stomatal responses to desiccation, high RH leaf regions have only a limited capacity to adapt after transfer to moderate RH conditions. It is suggested that the diminished stomatal closure in high RH-grown plants is the result of changes in the signalling pathway for ABA-related closure induced by a prolonged period (several days) at a low ABA level. A short increase of VPD (by decreasing RH or increasing temperature) once every 2 or 3 days is probably sufficient to overcome vase life problems of cut flowers grown at high RH. Testing the acclimation ability of stomata to desiccation by transferring high RH grown plants to low VPD for just a few days would be a simply and effective screening procedure for genotypes with more adaptable stomat

The use of imaging of the efficiency of photosystem II electron transport to visualise the effect of dry storage on the photosynthesis and stomatal closure of cut rose stems

Following their harvest, cut roses are generally stored dry prior to and during transport and only rewetted once they near the end of the chain. This treatment results in overall dehydration of the rose shoots and to the development of emboli within the xylem of the stems. A major consequence of this dehydration event will be stomatal closure as a result of the water stress that develops in the leaves. In addition to reducing water loss from the leaves, stomatal closure will also have major effects on leaf photosynthesis. Quantitative chlorophyll fluorescence imaging of leaves (or any other photosynthetic tissue) permits the visualisation of how efficiently light is being used to drive photosynthetic electron transport. Stomatal closure affects photosynthesis and thus photosynthetic electron transport. So, chlorophyll fluorescence imaging can be used to visualise the responses of leaves to the water stress imposed by cutting and the relief of water stress by rewetting. Results show that the degree of recovery of stomatal opening is generally only partial and that in addition to a persistent limitation of stomatal opening, there is an effect on photosynthetic electron transport due to processes acting at the level of the mesophyll. The results obtained illustrate the usefulness of chlorophyll fluorescence imaging to rapidly and effectively visualise and measure the effect of water stress on cut flowers and to quantify their recovery from this stres

300 AREA PACIFIC NORTHWEST NATIONAL LABORATORY FACILITY RADIONUCLIDE EMISSION POINTS AND SAMPLING SYSTEMS

Radionuclide emission points for 300 Area and Battelle Private facilities are presented herein. The sampling systems and associated emission specifics are detailed

Vroege bepaling van de effectiviteit van ALS-remmende herbiciden

MLHD, de methode om lage herbicide doseringen op maat en met controle op effectiviteit toe te passen is specifiek ontwikkeld voor fotosynthese-remmers. Telers ervaren de beperkte toepasbaarheid van de methodiek soms als bezwaar. Via onderzoek worden de mogelijkheden om MLHD te verbreden naar middelen met andere werkingsmechanismen verkend. In dit artikel wordt een overzicht gegeven van dergelijk onderzoek gericht op ALS(AcetoLactaatsynthase)-remmende herbicide

Myocardial perfusion scintigraphy: the evidence: A consensus conference organised by the British Cardiac Society, the British Nuclear Cardiology Society and the British Nuclear Medicine Society, endorsed by the Royal College of Physicians of London and the Royal College of Radiologists

This review summarises the evidence for the role of myocardial perfusion scintigraphy (MPS) in patients with known or suspected coronary artery disease. It is the product of a consensus conference organised by the British Cardiac Society, the British Nuclear Cardiology Society and the British Nuclear Medicine Society and is endorsed by the Royal College of Physicians of London and the Royal College of Radiologists. It was used to inform the UK National Institute of Clinical Excellence in their appraisal of MPS in patients with chest pain and myocardial infarction. MPS is a well-established, non-invasive imaging technique with a large body of evidence to support its effectiveness in the diagnosis and management of angina and myocardial infarction. It is more accurate than the exercise ECG in detecting myocardial ischaemia and it is the single most powerful technique for predicting future coronary events. The high diagnostic accuracy of MPS allows reliable risk stratification and guides the selection of patients for further interventions, such as revascularisation. This in turn allows more appropriate utilisation of resources, with the potential for both improved clinical outcomes and greater cost-effectiveness. Evidence from modelling and observational studies supports the enhanced cost-effectiveness associated with MPS use. In patients presenting with stable or acute chest pain, strategies of investigation involving MPS are more cost-effective than those not using the technique. MPS also has particular advantages over alternative techniques in the management of a number of patient subgroups, including women, the elderly and those with diabetes, and its use will have a favourable impact on cost-effectiveness in these groups. MPS is already an integral part of many clinical guidelines for the investigation and management of angina and myocardial infarction. However, the technique is underutilised in the UK, as judged by the inappropriately long waiting times and by comparison with the numbers of revascularisations and coronary angiograms performed. Furthermore, MPS activity levels in this country fall far short of those in comparable European countries, with about half as many scans being undertaken per year. Currently, the number of MPS studies performed annually in the UK is 1,200/million population/year. We estimate the real need to be 4,000/million/year. The current average waiting time is 20 weeks and we recommend that clinically appropriate upper limits of waiting time are 6 weeks for routine studies and 1 week for urgent studies