Profiling of spatial metabolite distributions in wheat leaves under normal and nitrate limiting conditions

The control and interaction between nitrogen and carbon assimilatory pathways is essential in both photosynthetic and non-photosynthetic tissue in order to support metabolic processes without compromising growth. Physiological differences between the basal and mature region of wheat (Triticum aestivum) primary leaves confirmed that there was a change from heterotrophic to autotrophic metabolism. Fourier Transform Infrared (FT-IR) spectroscopy confirmed the suitability and phenotypic reproducibility of the leaf growth conditions. Principal Component–Discriminant Function Analysis (PC–DFA) revealed distinct clustering between base, and tip sections of the developing wheat leaf, and from plants grown in the presence or absence of nitrate. Gas Chromatography-Time of Flight/Mass Spectrometry (GC-TOF/MS) combined with multivariate and univariate analyses, and Bayesian network (BN) analysis, distinguished different tissues and confirmed the physiological switch from high rates of respiration to photosynthesis along the leaf. The operation of nitrogen metabolism impacted on the levels and distribution of amino acids, organic acids and carbohydrates within the wheat leaf. In plants grown in the presence of nitrate there was reduced levels of a number of sugar metabolites in the leaf base and an increase in maltose levels, possibly reflecting an increase in starch turnover. The value of using this combined metabolomics analysis for further functional investigations in the future are discussed

Studies in Locational Analysis

Series 1

Operational Research in Environmental Planning

Environmental considerations are increasingly playing an important part in our lives and many problems are being raised. Operational research has a role to play in solving such problems and this special issue is devoted to the application of operational research methods to environmental planning. For this we were fortunate to receive a variety of high quality papers in the area. From these, eight were finally selected which, with the exception of the invited review, appear in alphabetical order with regard to the first named author. Charles ReVelle gives a wide ranging review on ‘Research challenges in environmental management'. He concentrates attention on five specific topics: water resources-management of parallel reservoirs; water quality management; solid wastes management; cost allocation; and air quality management. The treatment of each topic starts with background material giving a review of essential achievements to date, followed by some open problems together with some suggestions for possible further research. The issues raised and the problems posed will surely provide a challenge to researchers for many years to come. The remaining papers can be divided into three categories: theoretical, application and methodological. Of the two papers in the first category, the one by Fernandez et al. describes a general method for the nonconvex problem of locating an ‘undesirable facility' in a plane region based on the use of interval analysis. The other, by Richter and Sombruzki, is concerned with product recovery management as an aid to environmental planning and considers associated production planning and inventory control issues. Of the application oriented papers, Zhang et al. discuss the contribution that GIS can make in assessing the risk associated with a network link, an essential ingredient for planning the transportation of hazmat (hazardous materials). Reinhard et al. use the SFA and DEA techniques to estimate the environmental efficiency (the ratio of minimum feasible to observed use of environmentally detrimental inputs – e.g. nitrogen surplus) of Dutch dairy farms. The third paper in this group details features of a spatial DSS for forest ecosystem management with particular reference to the situation pertaining to the USDA Forest Service. Another paper concerned with hazmat transportation is that by Akgun et al. The particular aspect they treat is that of finding sets of dissimilar routes with a view to avoiding risk concentration. Finally, Jenkins develops a method to generate a range of scenarios for study in depth in such a way that the maximum amount of useful information can be obtained regarding a possible catastrophic release of pollutant. It is thus seen that this issue contains an interesting variety of topics related to environmental matters. For this we would like to express our gratitude to all who submitted a paper and to the referees for kindly giving of their time and effort. Finally, we would like to express our thanks to the editors who gave us the opportunity to undertake the preparation of the issue