Multi-point temperature measuring equipment for crop environment, with some results on horizontal homogeneity in a maize crop. 1. Field results.

The use of temperature measurements above, below and within plant stands in physiological and ecological studies is briefly reviewed and the choice of sensor and protection from radiation effects in measuring temperatures within a maize crop are discussed. The horizontal homogeneity of temperature was investigated. Measurements in 1973 and 1974 showed the greatest horizontal temperature difference at 1.8 m above ground level due to an increase in leaf area density just above the height where the crop became closed and air flow was reduced; at lower levels temperature differences increased as turbulence was reduced, and differences in soil surface conditions influenced temperature measurement. The need for a large number of measuring points in the lower parts of the canopy is emphasized. (Abstract retrieved from CAB Abstracts by CABI’s permission

Multi-point temperature measuring equipment for crop environment, with some results on horizontal homogeneity in a maize crop. 2. Equipment used.

Details regarding equipment used in obtaining field data on crop environment temp. published earlier [see FCA 30, 5292] are reported. Pt resistance mounting and error analysis, calibration of these resistances and data logger requirements and modifications are dealt with. Equipment details regarding the actual collection of accurately scanned field temp. are discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission

Groundwater and climate change: threats and opportunities

The important role of groundwater in adaptation to climate change is explored, and the competing threats and opportunities that climate change pose to groundwater systems are evaluated. This has been achieved through a review of current thinking on the complex interactions between human activities, climate and the hydrological cycle affecting groundwater quantity and quality, across different regions and time scales

Regulation of Azorhizobium caulinodans ORS571 nitrogen fixation (NIF/FIX) genes

Biological nitrogen fixation is the microbial process by which atmospheric dinitrogen (N 2 ) is reduced to ammonia. In all microbes studied, dinitrogen reduction is catalyzed by a highly conserved enzyme complex, called nitrogenase. The nitrogenase subunits and functions required for nitrogenase assembly and activity are encoded by the nitrogen fixation (nif/fix) genes.Nitrogen-fixing organisms can be roughly divided into two major groups: the free-living nitrogen fixing (diazotrophic) species, such as Klebsiella pneumoniae, Azotobacter vinelandii and Rhodobacter capsulatus, and symbiotically N 2 fixing organisms, such as Rhizobium species and Bradyrhizobium japonicum.The fate of the ammonia produced by these two distinct groups of nitrogen fixing organisms is quite different. While free-living nitrogen-fixing organisms will assimilate the ammonia produced for their own growth (diazotrophy), the strictly symbiotically nitrogen-fixing organisms (predominantly) excrete the ammonia into the cytoplasm of infected plant cells, to be assimilated by the host. The regulation of nitrogen fixation (nif/fix) gene expression is quite different as well, and has been difficult to compare directly between diazotrophs and strictly symbiotic nitrogen fixing organisms. The discovery of Azorhizobium caulinodans ORS571, a tropical rhizobium capable of both diazotrophy and symbiotic nitrogen fixation in stem- and root nodules induced on its host, the tropical shrub Sesbania rostrata, changed this situation and has allowed a direct comparison of (nif/fix) gene regulation in the diazotrophic versus symbiotic state. This unusual organism was chosen for the research reported in this thesis, which focuses on the expression of the central (nif/fix) regulatory gene nifA , a gene which is essential for diazotrophic growth and symbiotic nitrogen fixation, and which responds to a complex regulatory circuit.In chapter 2 a current review of the regulation of nitrogen fixation genes is presented. The review focuses on the regulation of nifA gene expression and NifA activity in different bacterial species.In chapter 3 the involvement of ntr-mediated control of the nifA promoter via the -24/-12 element is analyzed by site-specific mutagenesis and chimeric nifA - lacZ reporter gene fusions integrated into the A. caulinodans chromosome. The -24/-12 promoter element was shown to be important for nifA gene expression suggesting the involvement of a σ54 (NtrA; RpoN)-type transcription factor in nifA gene regulation.Chapter 4 addresses the involvement of a ntrA(rpoN) -like sigma factor in nifA expression, and reports the cloning and analysis of an A. caulinodans ntrA(rpoN) gene. Although the ntrA(rpoN) gene identified in this study was shown to control the expression of some of the A.caulinodans nif genes (like nifHDK) and nitrate assimilation genes, it did not appear to regulate the expression of nifA , suggesting the presence of an additional ( nifA specific) ntrA ( rpoN )-equivalent gene.To search for trans -acting factors involved in the regulation of the nifA expression, the in vitro interaction of proteins in A. caulinodans crude cell extracts with the nifA regulatory region was studied by gel retardation assays. Chapter 5 presents the binding of (a) sequence-specific protein(s) in extracts of A.caulinodans to the nifA 5' upstream region. However the nature of the protein(s) and the exact location of the binding site in the nifA 5' upstream region remains to be determined.During the preparation of crude cell extracts from A. caulinodans fi xLJ and fixK mutant strains, large amounts of a red/pink, UV fluorescent pigment was observed in the culture medium. Chapter 6 describes the isolation and characterization of this pigment.Chapter 7 describes the isolation and characterization of an leuA -like gene of A.caulinodans which was incidentally identified with an Escherichia coli fnr probe. Comparison of the 5' upstream region of the A. caulinodans leuA gene with the leu operons of other organisms suggest a conserved regulation mechanism for the expression (transcription attenuation), found in many amino acid biosynthetic operons.Finally in chapter 8 the current model for nitrogen fixation gene regulation in A.caulinodans, deduced from the studies presented in this thesis and previous data, is presented

Shelterbelts and farmers needs

As a response to desertification and long periods of drought in Northern Nigeria in the 1970s, the Kano State Forestry Department designed a programme of land rehabilitation using shelterbelts. It soon became clear, however, that the shelterbelts had design errors and had many disadvantages. Farmers had not been consulted when they had been established and this added to their sense of dissatisfaction with the measures implemented. In this article the authors use the Nigerian experience to stress the importance of actively involving farmers as well as researchers and policy makers in soil management and rehabilitation programmes

The use of photogrammetry in the conservation of painted outdoor sculpture:Adressing Jean Dubutffet’s <i>Jardin d'Email</i>

This research evaluates the use of innovative imaging technolo- gies to aid the conservation of large-scale contemporary painted outdoor sculpture. It explores photogrammetry and image- based 3D modelling as tools during the conservation of Jardin d’émail (1974) by Jean Dubuffet (1901-1985), owned by the Kröller-Müller Museum.In partnership with the 4D Research Lab at the University of Amsterdam, 3D digital models of the sculpture and two scale-models were created.This research assesses the effectiveness of using 3D digital models to inform the repainting of the sculpture’s black lines on white background as part of the treatment process. The use of photogrammetry to document the patterns and forms of the sculpture and scale-models is also evaluated. The creation of 3D digital models from the photogrammetric data allows for devi- ation analysis to be carried out, highlighting where areas of the scale-model and sculpture deviate significantly. The 3D models were uploaded on an app for use on tablets to enable responsive access during treatment. This research showed that photogram- metry is not only useful for large scale sculpture documentation, but can also aid the treatment of outdoor sculpture by producing geometrically accurate representations of the scale-model to be used as a reference during repainting

The use of photogrammetry in the conservation of painted outdoor sculpture:Adressing Jean Dubutffet’s <i>Jardin d'Email</i>

This research evaluates the use of innovative imaging technolo- gies to aid the conservation of large-scale contemporary painted outdoor sculpture. It explores photogrammetry and image- based 3D modelling as tools during the conservation of Jardin d’émail (1974) by Jean Dubuffet (1901-1985), owned by the Kröller-Müller Museum.In partnership with the 4D Research Lab at the University of Amsterdam, 3D digital models of the sculpture and two scale-models were created.This research assesses the effectiveness of using 3D digital models to inform the repainting of the sculpture’s black lines on white background as part of the treatment process. The use of photogrammetry to document the patterns and forms of the sculpture and scale-models is also evaluated. The creation of 3D digital models from the photogrammetric data allows for devi- ation analysis to be carried out, highlighting where areas of the scale-model and sculpture deviate significantly. The 3D models were uploaded on an app for use on tablets to enable responsive access during treatment. This research showed that photogram- metry is not only useful for large scale sculpture documentation, but can also aid the treatment of outdoor sculpture by producing geometrically accurate representations of the scale-model to be used as a reference during repainting