PhD, EngD, DM and MSc by research theses (Silsoe)

Permanent URI for this collection

https://dspace.lib.cranfield.ac.uk/handle/1826/7

Browse

Now showing 1 - 20 of 28

Open Access
Alternative chemical control of anthracnose and crown rot of banana caused by Colletotrichum musae
(2000-11) Khan, Sabir Hussain; Aked, Julia
Chemical alternatives to the fungicides currently used to control Colletotrichum musae infections on banana fruit have been investigated. Four isolates of C. musae cultured from anthracnose lesions on imported banana fruit were screened against the fungicides thiabendazole (TBZ) and imazalil incorporated into malt extract agar (MEA). Two of the isolates showed some tolerance to TBZ even at 1.24 mM (250 ppm), whereas all four isolates were very sensitive to imazalil at concentrations of > 0.017 mM (5 ppm). One susceptible (CM100) and one tolerant (CM103) isolate (to TBZ) was selected. Eleven chemicals were evaluated over a range of concentrations for their effectiveness in inhibiting the germination and mycelial growth of these isolates in vitro (on MEA). The chemicals were the antioxidants ascorbic acid, propionic acid, benzoic acid, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl paraben (PP), propyl gallate (PG), dimethyl sulphoxide (DMSO), thiourea and tannic acid and the natural plant product azadiractin. BHA, azadiractin, benzoic acid, PP and PG gave the highest levels of fungal inhibition in vitro. BHA at 5 mM completely inhibited the germination and mycelial growth of CM100 and CM 103 at 25°C. BHA (1 mM) in combinations with benzoic acid (1 mM), PP (1 mM) or imazalil (1.68 pM) completely inhibited germination and mycelial growth of CM103 at 14 and 25°C. The effectiveness of imazalil was not affected by the pH of the medium whereas the effectiveness of BHA was greatest at pH 3.5 and 6.5 and benzoic acid was more effective at lower pH values. C. musae was shown to produce nine extracellular enzymes in liquid medium which have not been reported before including lipases, phosphatases and hydrolases. BHA, imazalil and TBZ caused differential inhibition of the production or activity of these enzymes. The toxicity of selected chemicals was tested against anthracnose or crown rot infections of fingers or hands of banana fruits. Inoculations of C. musae were made with either mycelium in wounds in the banana peel or with conidia on the intact surface of the fruit or on the cut stalk or crown tissues. Of the alternative chemicals tested on their own, BHA and azadiractin gave the greatest inhibition of anthracnose and crown rot infections with dip treatments at 1 mM giving control levels ranging from 10-39% compared with 17.6-38.3% for imazalil (0.84 mM = 250 ppm). BHA (5 mM) in combinations with imazalil (0.84 mM), PP (10 mM) or benzoic acid (10 mM) suppressed anthracnose lesions (CM103) by 64.7, 54.9 and 35.3 %, and crown rot development by 70.5, 62.3 and 42.6 % at 25°C respectively. At 14°C these same combinations gave complete control of anthracnose lesions and crown rot development. TBZ was less effective at controlling crown rot (CM100 or CM 103) than imazalil alone or when in combinations with BHA. Combinations of BHA with imazalil but not with TBZ showed synergism both in vitro and in vivo. The cost/litre of the best trial treatment (BHA at 5 mM with imazalil at 0.84 mM) was less than that of imazalil at 1.68 mM (500 ppm). This suggests that food grade phenolic antioxidants such as BHA may be useful adjuncts to currently used fungicides such as imazalil for commercial control of banana postharvest diseases.
Open Access
Application of GIS and remote sensing for land use planning in the arid areas of Jordan
(2000-01) Ziadat, Feras M.; Taylor, John C.
Land suitability analysis formed part of a land use planning exercise in a development project aimed at improving agricultural productivity in the transitional Badia region of Jordan. Soil observations and soil maps were available at three levels of detail with differing coverage: level one (1:250,000 scale -complete cover), level two (1:50,000 scale - part cover) and level three (1:10,000 scale very limited cover). The development project selected the FAO Framework for Land Evaluation as the basis for land suitability analysis. This research investigated seven different calculation approaches for the processing of soil observations within soil map polygons using a GIS to derive land suitability ratings. These methods either use the soil observations to calculate the suitability of each soil mapping polygon or an interpolation technique (Voronoi diagram or Triangulated Irregular Network) between observation points. The overall map purity and homogeneity with respect to land characteristics were used to evaluate these methods. The quality of suitability maps varied according to the level of soil mapping and the method of processing the soil observations. The relative performance of the processing methods is discussed and recommendations for each level of mapping are proposed. The results showed that the purity of suitability maps was between 60 and 70% at the highest level of detail. Thus they should be used with caution for site specific analyses. Statements of map quality should be appended to suitability maps. The soil maps and observation points were derived and collected in a previous soil survey programme and georeferenced by map reading before the widespread availability of the Global Positioning System (GPS). When the data were integrated and overlaid on a satellite image within a GIS, a number of inconsistencies in georeferencing the data and in the attributes attached to them were revealed. Investigation and correction of these evolved into a major component of this work. Systematic errors caused by the use of different datums to georeference soil maps and observation points in the Jordan Soil and Climate Information System (JOSCIS) were detected. The map reading procedure also caused unsystematic errors in the locations of soil observations, which were re-measured at a sample of original observation sites using GPS. The correction of the unsystematic errors was not feasible due to the difficulty and cost of relocating all observation points. Errors in the attributes attached to the observation points were caused by survey recording procedures, highlighting the need for an examination of the data before analysis. The systematic and attribute errors were corrected and the implication for suitability analysis examined. The areas and spatial distribution of different suitability classes were affected increasingly as the level of mapping became more detailed. The presence of all these errors was sufficient to create errors in the derived land suitability maps, which could lead to incorrect land use planning decisions. The integration of satellite imagery, soil observations and soil mapping polygons within a GIS was indispensable for quality control of the data. The highest purities of suitability maps using existing soil mapping polygons were between 60% to 70% at level three but they only covered veiy limited areas. This indicated the need to extend mapping at this detail for site-specific planning and if possible, to increase the purity of soil mapping units. This was investigated by integrating satellite imagery and topographic data in a GIS. A 3-D perspective view of a Landsat TM image using an air photo-derived DEM was the most promising way of using the available data. Further research is needed to investigate the interactive use of air photo-derived DEMs and Landsat images, with more focus applied to site specific planning and field verification of the technique. Although this work was necessarily focussed on the issues and problems particular to one data set used in a Jordanian context, a number of general lessons have been learned. Firstly, careful examination of all input data is necessary to eliminate georeferencing and attribute errors. Secondly, overlay of input data onto a geocoded satellite image is extremely useful for detecting potential sources of input data errors and is recommended. And thirdly, GIS is indispensable for investigating existing data for errors and exploring new methods of analysis.
Open Access
An attempt to extend means-end theory: An investigation of the linkages between choice behaviour and values
(2003-04) Manyiwa, Simon; Crawford, I. M.
The research problem was identified as a lack of means - end theory linking choice behaviour to values. The aim of the study was, therefore, to determine whether or not the means-end theory could be extended to linking choice behaviour to values. The research was focused on the following two research questions: ( 1 ) what , if any, are the conceptual categories in the means-end theory linking choice behaviour to values? (2) How, if at all, are the conceptual categories in the means-end theory linking choice behaviour to values connected together? A case research method was adopted for the empirical investigation of the study, focusing on food choices in the family context. The fieldwork, carried out in the UK, was done in two phases, i.e. the pilot study and the main study. The research findings suggest that the conceptual categories linking choice behaviour to values consist of the following conceptual categories: choice behaviour, attributes of choices, consequences, and values. In addition, the research findings indicate more dominant direct linkages between the adjacent conceptual categories than between the nonadjacent conceptual categories. The dominant direct linkages between the adjacent conceptual categories suggest that the conceptual categories linking choice behaviour to values are hierarchically connected together. The main implication of the research findings is that researchers can establish linkages between choice behaviour and values on the basis of actual choices in specific social contexts, instead of using cognitions as a surrogate for choice behaviour.
Open Access
Biological and artificial receptors in affinity sensor for water toxins detection
(2003-01) Lotierzo, Manuela; Tothill, Ibtisam E.
Molecular recognition is the basis for many of the chemical and biochemical phenomena occurring in living organisms. For example, antibodies, which are one of the different classes of natural receptor molecules, are capable of selectively recognising a specific target molecule or structure. They are therefore routinely utilised as analytical reagents in clinical and research laboratories. The design and synthesis of biomimetic recognition systems, capable of binding target molecules with affinities and specificities comparable to natural receptors, is regarded as one of the greatest challenges in bioorganic chemistry. Molecularly imprinted polymers (MIPs) have been shown to mimic the binding sites of antibodies and are, therefore, constantly gaining in interest for applications based on specific molecular recognition. This project aimed to develop affinity sensors for the detection of algal and cyanobacterial toxins such as microcystin-LR and domoic acid in water samples. Following the investigation, a heterogeneous direct competitive enzyme-linked immunosorbent assay (ELISA) format for microcystin detection was developed. The system was then transferred to an affinity membrane sorbent based ELISA. This was an amenable format for immunoassay incorporation into a disposable amperometric immunosensor device. A three-electrode system immunosensor was fabricated using thick film screenprinting technology. Amperometric HRP transduction of hydrogen peroxide catalysis, at low reducing potentials, versus Ag/AgCl reference and carbon counter electrode, was facilitated by hydroquinone mediated electron transfer. A detection limit of 0.5 pg V1 for microcystin-LR was achieved. The work undertaken also describes the design and synthesis of biomimetic recognition systems based on MIP, capable of binding target molecules with affinities and specificities on a par with natural receptors. A MIP synthetic receptor selective for microcystin-LR was studied using an enzyme-linked competitive assay and found to be comparable to polyclonal antibodies, whilst the MIP had superior stability over natural receptors. Methacrylic acid based MIP had a detection limit of 1 pg I'1, approxilately twenty times higher than that of anti microcystin-LR polyclonal antibody. A molecularly imprinted polymer was also directly synthesised by grafting on the gold chip of a surface plasmon resonance (SPR) based bioanalytical instrument system: the BIAcore 3000™. Such a chip based platform allowed a simple test of the specific MIP receptor for the marine toxin domoic acid. A fiill characterisation of the grafting procedure was initially carried out on a bare gold surface, and each step of the polymerisation was investigated by contact angle measurements and AFM imaging. The surface photo-initiated MIP film was obtained and its thickness and homogeneity evaluated. Domoic acid is a molecule that is too small for direct analysis, hence a competition reaction was performed in presence of the conjugate DA-HRP and a detection limit of 2 fig f 1 could be achieved with the BIAcore 3000™ system.
Open Access
Calibration of pesticide leaching models
(2002-09) Dubus, Igor G.; Brown, Colin D.
Complex deterministic models are being used within the context of pesticide registration to assess the potential for crop protection products to impact on the environment. Although calibration is in many ways at the heart of pesticide fate modelling, it has received little attention in the past. Sensitivity analyses were carried out for the four main leaching models used for pesticide registration in Europe (PELMO, PRZM, PESTLA and MACRO) using four different leaching scenarios and two approaches to sensitivity assessment (one-at-a-time and Monte Carlo sensitivity analyses). Also, an inverse modelling approach was used to estimate values for sorption and degradation parameters from leaching data for seven lysimeters using the PESTRAS model. The overall conclusions of the PhD can be summarised as follows: 1. Sensitivity analyses for the four leaching models mainly used for pesticide registration in Europe demonstrated that predictions for pesticide loss are most sensitive to parameters related to sorption and degradation. In a small number of scenarios, hydrological parameters were found to also have a large influence on predictions for pesticide loss. 2. Sensitivity analysis proved to be an effective approach not only for ranking parameters according to their influence on model predictions, but also for investigating model behaviour in a more general context. However, the research questioned the robustness of the Monte Carlo approach to sensitivity analysis as issues of replicability were uncovered. 3. Inverse modelling exercises demonstrated that non-uniqueness is likely to be widespread in the calibration of pesticide leaching models. Correlation between parameters within the modelling, such as that between sorption and degradation parameters when predicting pesticide leaching, may prevent the robust derivation of values through an inverse modelling approach. Depending on the calibration system considered, these parameters may act as fitting variables and integrate inaccuracies, uncertainties and limitations associated with experimental data, modelling and calibration. 4. A special implementation of error surface analysis termed lattice modelling was proposed in the PhD as an efficient technique to i) assess the likely extent of nonuniqueness issues in the calibration of pesticide leaching models; and, ii) replace traditional parameter estimation procedures where non-uniqueness is expected. Care should be exercised when assessing the results obtained by both modelling and inverse modelling studies. Suggestions to improve the reliability in the calibration of pesticide leaching models have been proposed.
Open Access
Controlled and modified atmosphere storage of tomatoes
(1995-07) Batu, Ali; Thompson, A. Keith
From the literature it was concluded that various factors could influence the storage life of tomatoes. These included harvest maturity, storage temperature, storage humidity and the level of gases in the storage atmosphere using modified atmosphere packaging (MAP) and controlled atmosphere storage (CAS). However, what was not clear from the literature was how (many of) these factors interacted and there was little information on the effect at long term MAP or CAS on eating quality of tomatoes. A series of experiments were, therefore, carried out to investigate the above factors. In order to carry out experiments preliminary tests were performed on tomatoes and compared to those given in the literature. These were to establish relevant quality criteria for the fruit in order to judge the comparative effects of the various treatments and included a texture measuring test and minimum criteria for objective colour measurements. Storage humidity was shown to interact with fruit harvest maturity in that ripening time of fruits increased in high humidity levels. The quality of tomatoes harvested at the mature green stage of development and stored in low or medium humidity was approximately the same when they were ripe. However, fruit ripened at high humidity had a significantly better colour, were more acidic and firmer than those ripened at low humidities. Tomatoes harvested at the pink stage of maturity and ripened at low humidity levels were firmer, probably because the time taken to ripen was shorter than those ripened in medium and high humidity. There were interactions between MAP and temperature in that MAP was more effective in delaying ripening at 13°C than at 20°C. MAP interacted also with tomato harvest maturity where it was more effective in delaying ripening of fruit harvested at the mature green stage of maturity. Colour development was affected by storage temperature. In storage at 13°C maximum reddening occurred about 10 days later than in those stored at 20°C. There was an interaction between packaging films and ripening time of fruits. Tomatoes ripened later when they were sealed in films which were less permeable to O2 , CO2 and water vapour than when they were sealed in higher permeable films. Packaging films also affected fruit firmness of tomatoes. All green tomatoes sealed in 25 micron thick polypropylene (PP) film were very firm even after 60 days of storage at 13°C or 20°C, compared to other films. Ripening time and subsequent quality of fruits were influenced by their harvest maturity. Tomatoes harvested at the mature green stage and sealed in 50 micron thick polyethylene (PE50) or PP films had delayed development of the red colour after 30 days of storage and those tomatoes also had the lowest weight loss and the highest soluble solids after 60 days of storage. Storage temperature affected the acidity and total soluble solids (TSS) contents of fruits. These were higher at 13°C than at 20°C for those harvested at either the mature green or pink stage. The CO2 levels affected the colour changes of the tomatoes. The colour of tomatoes harvested at the pink stage of maturity did not change when they were stored in 6.4 % CO2 with 5.5 % O2 and 9.1 % CO2 with 5.5 % O2 even after 50 days and in some cases after 70 days storage. The red colour development of the tomatoes exposed to less than 6.4 % CO2 increased, whereas red colour (Minolta a*.b*-1 values) decreased with CO2 levels above 9.1 % during storage. There were differences in ripening of tomatoes between MAP and CAS where mature green fruits in MAP ripened earlier than the same fruits in CAS. The differences were probably due to ethylene accumulation in MAP which would not occur in CAS because of the continuous gas flushing. It was concluded that with the combination of reduced temperature and MAP or CAS, fruit could be stored for 60 or 70 days and still be marketable in terms of appearance, firmness, flavour and overall acceptability.
Open Access
Design of a novel punch planter capable of producing equidistant seed spacing of irregular shaped seeds
(2002-09) De Resende, Ricardo Capucio; Brighton, James L.
Plants uniformly spaced in the field have a more efficient use of resources, due to their even distribution. There are also a better ability to compete against weeds, less spread of disease and lodging. Consequently the yield should be improved. Precise seed placement and seed location in the field are important for the management of the crop at a plant-scale level, for such operations as mechanical weeding or herbicides applications. A novel concept of a precision drill was developed to achieve an advanced control of seed placement and location in the soil. The fundamental principle adopted, was to trap seeds inside holes in the soil, to eliminate seed bounce and roll in the furrow. The concept is simple and consists of only three moving parts, two punch wheels and a fen, to precisely place the seeds in the soil. A rotary punch planter prototype was designed and built, including a vacuum operated seed metering unit and an air delivery system. The prototype was tested under laboratory conditions to determine its performance in relation to seed placement, when planting wheat and pelleted sugar beet seeds. The experiments were done in a soil bin at 4, 6 and 8 km/h Seed spacing and depth were set to 18 cm and 3 cm, respectively. The results show that, once a seed had been successfully selected the prototype had the ability to precisely place seeds in the soil for wheat and sugar beet seeds, at all speeds tested. The grand mean for precision was 12.2%. The CP3 value for wheat and sugar beet at 8 km/h were 26.2 % and 60.8 %, respectively. The main problems encountered were seed selection at higher speeds, and incorrect seed transfers from the seed metering unit to the delivery punches, which occurred for both seeds at all speeds. The concept has proved to be effective and modifications of the seed metering mechanism to improve its performance is recommended to further improve upon the concept.
Open Access
The design of an improved efficiency lavender harvester
(2005-01) Dimitriadis, Christos I.; Brighton, James L.
The introduction of new methods to solve a specific task was always the ignition for the human mind to find new solutions. Considering the new demands in mechanical lavender harvest for oil production a novel harvester has been developed employing the stripping technique (Klinner et al., 1986a,b,c,d; Hobson et al., 1988) developed for the harv~~ting of cereals. The harvester works in a unique way for this crop by removing the flower :~eads_ in the field, leaving the majority of the stems intact. Convention~! harvesting methods such as hand harvest and mechanical harvest using a . cutting mechanism collects both the flower head and a cut length of the stem. This was found to be an inefficient method for the harvest of lavender because most of the oil produced by the plant (97.5 % by weight - Venskutonis, 1997) is located on the flower. Also using these methods the amount of stem collected increases the transportation and the distillation costs, generates more demanding designs, and removes the stem from the field that could otherwise be left as a natural nutrient. Taking this into account and that the British Pharmacopoeia directs that in making the most refined lavender oil (for medicinal use) it should be distilled from the flowers after they have been separated (stripped) from their stalks (Grieve, 2001) the proposed harvesting technique is ideal for the production of high quality lavender oil.
Open Access
Detection of inappropriate cell proliferation in breast epithelium leading to breast cancer
(2004-11) Degan, Simone A.; Woodman, Anthony C.; McCarthy, Keith; Bristol, James B.
Breast cancer is predominantly caused by unrestrained cell proliferation. Proliferation is a complex process mediated by a network of signals that converge to a point called the ‘initiation of genome replication’ after which either proliferation or cell death could take place. The minichromosome maintenance (MCM) proteins are located at this point and play a pivotal role in regulating DNA replication. The detection of an aberrant level of such proteins can be of use in early breast cancer diagnosis. The main aim of this thesis was to propose a new system to detect inappropriate cell proliferation in breast epithelium. An in vitro model using cancer cell lines was developed to lay the foundation for subsequent studies employing human breast specimens. The application of the in vitro findings in breast excisions allowed assessing of the specificity and sensitivity of the biomarkers to ascertain slowly proliferating neoplastic cells. The most striking finding of this study was the abnormal presence of the MCM proteins in tumour compared to normal tissues with a typical pattern of expression unique for the histological classification of the lesion. The potential of MCM proteins as indicators of cell proliferation defects was further investigated with association studies with Ki-67, Bcl-2 and ER. MCM consistently identified a higher proportion of proliferating cells compared to Ki-67 suggesting that they are interesting markers of the Gi/S-phase. In fact, the MCM proteins start to co-localise in early Gi whereas Ki-67 is almost absent in this phase. Importantly, MCM proteins could recognise not only the proliferating compartment of the tumour but also those cells with replication potential. Based on these findings, the novel MCM biomarkers can be helpful in identifying both malignant and potentially malignant breast tissues. This feature can be useful in predicting patients at risk of tumour progression.
Open Access
The development of techniques of assessing soil compactability
(1993-06) Earl, Richard; Spoor, Gordon
The recent decline in farming profits has prompted an urgent need to increase efficiency, either by increasing outputs or reducing the cost of inputs. Soil compaction can influence adversely all stages of crop development, and hence yield, and is expensive to ameliorate in terms of time taken and power required. Minimum cultivation or direct drill crop establishment systems can reduce inputs, however, they are very susceptible to compaction from the previous season. There is a need to develop a greater understanding of the compactive nature of soil, and hence trafficability and workability, in relation to the selection of appropriate machinery to carry out agricultural operations. A study of research on soil compaction revealed that the majority of work to date has been carried out using disturbed soil samples in laboratory situations. The aim of this project is to develop techniques and models, based on field data, for assessing the susceptibility of soils to compaction by agricultural machinery. Work, conducted during this study, was carried out in the field in a range of soils, crops and climatic conditions. The study was approached by dividing the project into two sections:- (1) Prediction of trafficability and workability on a go/no-go basis. Soil water suction (h), soil moisture deficit (SMD) and cone penetration resistance were monitored at six field sites, under grass and an arable crop, covering a range of agricultural situations commonly found in central and eastern England. Strong correlations were found to occur between both h and SMD and:- (a) a qualitative assessment of soil condition, and (b) cone penetration resistance. These data formed the basis of models for predicting trafficability and workability at a given site on a particular day, and at any 5km square in England and Wales as an aid to business planning. (2) Assessment of the compactive nature of soil during loading. A methodology was developed which provides a measure of the susceptibility of soil to damage if land is trafficked when in an unsuitable condition. It is based on results of plate sinkage tests, in conjunction with those from confined compression tests, performed in the field using tractor-mounted equipment. Soil behaviour during compression was found to be governed by three phases:- (a) compaction with uniform lateral stress, (b) compaction with increasing lateral stress, and (c) displacement of soil laterally. Mathematical models are presented for predicting, for a given load and soil, the deformation phase and extent of disturbance likely to occur. The prediction models developed during this study provide a new approach to the selection of, and assessment of damage by, agricultural machinery.
Open Access
Early detection and monitoring of fuel leaks
(2005-08) Huntley, Sharon L.; Setford, S.
A novel integrated detection system· has been developed to protect the environment from hydrocarbon fuels leaking from large-scale storage facilities. Over the last decade, land and subsequent groundwater contamination from hydrocarbon fuels has been identified as the major threat to drinking water resources across Europe and the United States. The integrated system developed within this work has two main components: (1) 'Early warning' free-phase fuel leak detection sensors; (2) A novel immunoassay field test for rapid, in situ follow-up analysis of contaminated sites through determination of the extent of the contamination and early indication of dissolved-phase fuel migration. (1) A prototype optical reflectometric device has been developed, in conjunction with state-of the-art data acquisition and relay technology to provide a simple, low-cost hydrocarbons monitoring solution. In extensive field trials, this system has been evaluated as a multiple-array, sub-surface, remote leak detection and monitoring system for early detection of free-phase hydrocarbon contamination. The sensors respond to all. free phase hydrocarbons and can determine plume movement through soil. Preliminary leak information from these sensors can be combined with subsequent, quantitative site analysis using the immunoassay to provide an integrated, highly sensitive and low-cost solution for long term monitoring and analysis. (2) A novel ELISA has been developed for detection of the most controversial fuel oxygenate - \ methyl tert-butyl ether (MTBE), identified as the most major threat to groundwater (and consequently drinking water) resources above any other hydrocarbon contaminant. The ELISA is a classical competitive immunoassay involving free MTBE and a novel antigen consisting of an MTBE analogue covalently bound to BSA. The ELISA was optimised and transposed into a magnetic bead format, the detection range was 0.5-5000 ppm (IC50 5 ppm, assay time 65 minutes). Also detectable are MTBE degradation products TBA, TBF and alternative fuel oxygenates TAME, DIPE and ETBE. MTBE is highly soluble in water and so is an excellent marker for assessing the extent of site contamination. This integrated detection system potential provides a sensitive, cost-effective solution for early detection, analysis and surveillance of petroleum fuel contamination in a range of applications.
Open Access
Electrochemical method for the rapid in situ screening of heavy metals in soil and water samples
(2004-03) Cooper, Joanne; Setford, S.; Bolbot, J. A.; Saini, S.
The aim of this work has been to develop a field-based electrochemical sensor for the detection of cadmium (Cd), lead (Pb), copper (Cu), zinc (Zn), arsenic (As) and mercury (Hg) in soil and water samples. In situ analysis, using rapid sample screening tools, can facilitate monitoring and remediation processes by minimising delays and substantially reducing costs. Disposable screen-printed electrodes (SPEs) have been fabricated using low-cost thick film technology. Carbon SPEs, coupled with anodic stripping voltammetry (ASV), provided a rapid, inexpensive in situ electrochemical screening sensor capable of simultaneously detecting Cd, Pb and Cu in soil and water samples in the microgram per liter range (pg I*1). A simplified soil extraction procedure, using 1 mol I'1 aqua regia and a three minute ultrasonic sample agitation, was developed for use with the sensor, addressing the lack of existing field-based soil extraction protocol. Extraction efficiency was evaluated using a soil certified reference material (CRM). Recoveries of 64%, 52% and 57% for Cd, Pb and Cu respectively were obtained, with a relative standard deviation (RSD) of <8% for all analytes (n=10). 82 soil samples were tested using the combined extraction + ASV sensor and compared against standard ICP-MS analysis. Correlation coefficients of 0.9782, 0.9728 and 0.9869 for Cd, Pb and Cu, respectively, indicated a good linear relationship between the two methods. A novel gold (Au) SPE, fabricated using a curable Au ink, was next evaluated for the detection of As and Hg. This is an improvement in the current state-of the-art as no surface modification or subsequent electrode adulteration to facilitate metal analyte depositioning is required. Furthermore, the Au ink can be cured at a low temperature (130°C), permitting electrode fabrication using disposable, cheap, plastic substrates. A patent has been filed. A limit of detection (LOD) of 2.7 pg I"1 and 1 pg I"1 for As3+ and Hg2+, respectively, was obtained following a 30 s depositioning. Speciation measurements for As were performed by reducing As5+ effectively over a short (10 min) reduction time using cysteine. An LOD of 42 pg f 1 following a 30 s depositioning was obtained. Initial studies also indicated the possibility of using the Au SPEs for measuring Cd, Pb and Cu, providing an alterative Hg-free procedure.
Open Access
Erosion hazard assessment in the upper Ewaso Ng’iro basin of Kenya: application of GIS, USLE and EUROSEM
(1999-09-15) Mati, Bancy Mbura; Morgan, R. P. C.; Gichuki, F. N.; Quinton, J. N.; Brewer, Timothy R.; Liniger, H. P.
A methodology was developed for assessing soil erosion hazard in the Upper Ewaso Ng’iro basin of Kenya, using Geographic Information Systems (GIS), the Universal Soil Loss Equation (USLE) and the European Soil Erosion Model (EUROSEM). The USLE was used in a GIS environment by creating thematic maps of R, K, L, S, C and P and then calculating soil loss by raster-grid modelling with Arc/Info GRID. The rainfall erosivity factor (R) was derived from relationships between rainfall amount and erosivity using erosion plot data from within the catchment. The nature of the relationship was found to be a function of agro-climatic zones of the region. Mean annual erosivities ranged from 145 to 990 J m'2 hr'1. For a given amount of rainfall, erosivity was higher in zone IV than in the wetter zones II-III. The soil erodibility factor (K) was estimated using the USLE nomograph and data from laboratory analysis of field samples collected from representative major soil mapping units. The K-values were low to medium, ranging from 0.10 to 0.25 over 84 percent of the basin. The topographic factor (LS) was obtained by creating Digital Elevation Models (DEMs) of the basin with TOPOGRIDTOOL of Arc/Info. These were then used to determine the slope steepness and length factor values, calculated with raster-grid modelling. Although DEMs proved a useful tool, maximum values of both steepness and length had to be set in this reconnaissance study to achieve reasonable results. A finer resolution of input data and a smaller grid cell size are needed for accurate determination. The cover and management factors (C) were obtained by determining the land cover types within the basin using remotely sensed data (SPOT 1 colour composite prints) and ground truthing studies. The factor values were estimated from USLE guide tables and measurements of cover from plots and test sites. Some 70 percent of the basin is covered by rangelands. The conservation practice (P) factor values were estimated from USLE guide tables and then applied to areas where soil conservation had been introduced according to maps obtained from the Ministry of Agriculture. The USLE was validated using data from erosion plots. A value of R2 = 0.645 was obtained between predicted and measured values but the standard error was rather high (e = 5.745 t ha’1 yr'1). Using an annual soil loss of 9.0 t ha'1 yr'1 as tolerance level, some 36 percent of the basin was found to experience unacceptably high erosion rates. Most of this area was communal grazing land and cropland where soil conservation measures had not been applied. A critical land cover type within the grazing land is shrubland, where vegetation cover is less than 40 percent and high erosion risk was predicted and confirmed by field surveys. EUROSEM could not be integrated within a GIS in the time available for research. It was therefore simulated outside GIS environment, where it was applied to Embori and Mukogodo plot data using separate data sets for calibration and validation. Calibration was used to obtain input parameters for saturated hydraulic conductivity, cohesion and Manning’s roughness coefficients. Validation gave correlation coefficients of 0.907 and 0.840 for predictions of storm runoff and soil loss respectively at Embori; the corresponding values for bare soil plots at Mukogodo were 0.895 and 0.577. However, EUROSEM predicted runoff poorly (R2 = 0.570) and failed to predict soil loss at all the vegetated plots at Mukogodo. The model was applied to simulated vegetation covers of barley, maize, grass and forest for a 36.7 mm rainstorm at Embori. The simulated soil losses showed an exponential decrease with increasing cover. At a threshold cover of 70 percent, soil loss diminished to zero under grass and forest and decreased to a minimum value under barley and maize. These results support the USLE simulations, which showed that areas with more than 70 percent cover (such as forest) had a low erosion hazard, even with steep slopes and high rainfall erosivities. This research has demonstrated that GIS can be used with the USLE to assess and quantify erosion hazard, giving results that can be used for conservation planning. EUROSEM can be applied successfully to bare soil and cropland, but application to other land covers requires further investigation. Land cover and topography are the main factors controlling the spatial distribution of soil loss in the Upper Ewaso Ng’iro basin. Future conservation activities should be concentrated on the rangelands.
Open Access
An evaluation of the responses of some tea clones to environment in Kenya
(1995-02) Ng'etich, Wilson Kipkoech; Stephens, William; Othieno, Caleb O.
An experiment set up at four sites in Kericho, Kenya was used to investigate Genotype x Environment interactions of four tea clones of commercial and scientific interest. Small differences in environment resulted in large variations in dry matter production and yield between sites and clones. The largest dry matter was from clone TNI 4/3 (291 ha'1) but it had low yield (2.11 ha'1/ 1). By contrast, the largest yield was from clone S15/10 (3.81 h a 'V 1), which gave the smallest dry matter ( I S th a 1). These contrasting responses in dry matter and yield were analysed in terms of the interception of solar radiation, radiation use efficiency, partition of dry matter and components of yield. The differences in clonal dry matter production were attributed to site to site variability in solar radiation and temperature which affected the rates of ground cover development and the solar radiation interception. The differences in yield were attributed mainly to differences in air temperature and saturation deficits of the air between the sites which affected the shoot replacement cycles through rates of shoot extension and development. Differences in measured and derived environmental variables between the sites were found. Incident solar radiation differed between the sites by up to 2.4M Jm 2 d 1. Differences in mean air and soil temperatures between the extreme sites were 2.5 °C and 3 °C respectfully. A lapse rate of 6.1 “Ckm*1 for mean air temperature was found. Annual rainfall amounts also differed between the sites by up to 700 mm. There were no differences in wind speeds, but there were large differences were in saturation deficits (0.5 kPa) and évapotranspiration (1 mm d*1). During the course of the experiment light interception ranged from less than 5% at planting to more than 80% in April 1994. Radiation use efficiencies for dry matter ranged from 0.30 to 0.45 g MT1 in the clones studied and appeared conservative with respect to temperature across the sites. Clone TNI4/3 had the lowest base temperature for shoot extension (6.1 °C), while clone BB35 had the highest (10.4 °C). The base temperatures for shoot extension were 1.3 to 2.9 °C higher than those for development, hence the differences in shoot lengths between sites. Shoot replacement cycle ranged from 57 days to 110 days between the sites and was the main determinant of yield. Abstract Silsoe College WK Ng’etich PhD. 1995 CranfisM,m The dry matter content of shoots varied between sites and seasons and ranged from 18% to 33%. Mean shoot dry mass was inversely proportional to temperature, ranging from 6 to 12% difference between extreme sites. Loss in yield due to water stress during the dry seasons ranged from 14 to 20% across the sites. Yield losses due to ‘hut sites’ ranged from 10 to 50%, while that from hail damage accounted for up to 20% of annual yields. These results are discussed in the light of other work in Kericho and southern Tanzania. The thesis concludes by considering the implication of the results for the tea industry.
Open Access
Feasibility of on-farm reduction of nitrate pollution in subsurface drainage water
(1996-05-23) Hughes, Edmund John; Spoor, Gordon
Nitrate polluted water from agricultural drainage systems is currently treated by the water industry for mains supply. Moves towards a polluter pays policy resulting from European Union legislation and consumer pressure will, however, have major implications for the agricultural industry. The aim of this study was to identify, investigate and evaluate on-farm strategies for reducing nitrate pollution in subsurface drainage water. The high peaked nitrate rich discharges of drainflows from agricultural catchments in late autumn present significant management problems. One possibility which was examined is for polluting drainflows to be identified, intercepted and diverted into a holding pond or reservoir. Once stored, possible effective handling strategies include: long term storage, dilution, recirculation of the polluted water back onto the .land, and anaerobic treatment. Anaerobic treatment is a method of reducing nitrate to harmless nitrogen gas, however, lower temperatures in late autumn would suppress microbial activity, and possibly treatment performance. Further detailed laboratory study was carried out to assess the potential of anaerobic treatment during winter. Initially, the hypothesis that the nitrate concentration of drainage water could be reduced when applied to soil was tested, leading to the conclusion that it was only possible when a readily utilisable carbon source was continuously present. Glucose was added to water with a nitrate concentration of 1 00mg/1 and applied to soil columns. Complete reduction of nitrate concentration was achieved at 10°C, demonstrating the feasibility of anaerobic treatment during winter. The study also confirmed the optimum application ratio of glucose-carbon to nitrate-nitrogen as 1.65 to 1, and the environmental threshold as a redox potential of 200m V. Attached growth water treatment systems which utilise soluble carbon sources are, however, unsustainable because clogging of the porous media by microbial biomass results in hydraulic failure. The hypothesis that organic materials be used both as carbon source and the microbial growth site was tested. Provisional examination of the biodegradability of several organic materials demonstrated that sugar beet could upon degradation be a source of readily utilisable carbon. Sugar beet was subsequently used in small-scale laboratory based nitrate reducing water treatment systems. An average treatment performance of 23 grams of nitrate-nitrogen reduced per cubic metre of bio-reactor per day was achieved by maintaining a near neutral pH environment with the addition of crushed limestone. Clogging was not experienced and therefore flow rate was both sustainable and controllable. An empirical based model was developed to predict the required flow rate of drainage water through the bio-reactor for a specified nitrate concentration reduction, ammonia concentration, and redox potential. Examination of drainflow data enabled polluting drainflow volumes and their associated average nitrate concentrations to be quantified, to form the basis of .a design specification for the proposed on-farm strategies. Designs for each strategy were made and limitations on use identified. Approximate costs were calculated and compared to the cost of on-farm anaerobic treatment utilising methanol as the carbon source. This demonstrated that treatment strategies offer a capital cost saving due to reduced design storage capacities, however, operating costs and the additional management expertise required make them less attractive to the farmer. Dilution has potential in areas where excess winter rainfall exceeds 200mm, however, the volume of water that can be diluted is limited. Recirculation requires further investigation, but has potential in areas of low excess winter rainfall and high soil moisture deficits, and where irrigation equipment is already available. Long term storage satisfies all the requirements for on-farm suitability, and would provide an additional environmental benefit of on-farm water conservation, at a cost 25% greater than that for off-farm water treatment alone.
Open Access
Improving the performance of water delivery systems in the Dez and Moghan irrigation schemes in Iran
(2005-09) Hedayat, Najaf; Weatherhead, E. Keith
Despite the importance of efficient irrigation management for sustainable agriculture in semi-arid and arid regions of the world, poor water delivery is widespread. Following recent rural reforms in Iran, which have changed the land holding regime, cropping pattern, and market system, the present canal management is no longer responsive to the new challenges of farmers in irrigation schemes such as the Dez and Moghan. This research aims to identify an appropriate canal management model for improving water delivery, using the stakeholders’ own views and understanding of the local issues. After reviewing the literature, four expert workshops were organized to identify important issues. A postal survey of 100 farmers, 50 extensionists and 50 water agency staff was then undertaken. This was then augmented by 36 semi-structured and open-ended interviews with stakeholders not covered by the survey. The majority of all three-stakeholder groups agreed that present canal management in both the schemes is not appropriate and causes various problems, but they did not agree on the causes of the problems. The majority view among the farmers and extensionists was that inequity and inflexibility, due to poor operation and maintenance (O&M) of the main and secondary canals, were the most important causes of poor water delivery. In contrast, the agency staff regarded group conflicts and environmental impacts, due to poor O&M in the tertiaries and quaternaries and poor on-farm operations, as the most important. The perceptions of the stakeholders on water delivery-related issues were similar on the two schemes. The farmers and extensionists had similar views on all issues except on water charges, where the extensionists (agreeing with the agency staff) suggested that present charges were too low to reflect the O&M costs. In contrast, the farmers thought that higher charges alone would not help, because the problems lie with poor design and the present inappropriate management system. The farmers and extensionists thought that neither purely technical nor purely nontechnical approaches alone would be adequate to resolve the problems. They supported an integrated management model, based on the traditional Iranian Miraab system. Although the survey responses suggested that all three-stakeholder groups would support this, the interviews suggested that majority of the farmers and extensionists thought some of the agency staff would resist its implementation because the farmer managed water distribution system would be seen to be a threat to their authority. All three groups thought that the government would support the implementation of the Miraab system. The key implications of the research is that the stakeholders consider the present management of the Dez and Moghan schemes is not responsive to the challenges in the post-reform era, and that they are more likely to be met by a system that is based on a bottom-up approach rather than one that is imposed by the state agencies. They consider that the governments are not always the best resource manager, and that a farmer managed water distribution system (e.g. the Miraabs) could do a better job. The research confirmed the importance of consulting different stakeholder groups, who might have different attitudes and perceptions of the problems and potential solutions.
Open Access
A mathematical model to predict surface runoff under sprinkler irrigation conditions
(1997-06) Ghorbani, Behzad; Kay, M. G.
Runoff from agricultural areas under sprinkler irrigation systems is a big problem. This is because runoff not only reduces water use efficiency (WUE), but also reduces soil fertility through depletion of fertilisers and pesticides, causes non uniformity of soil water content along the field slopes and ultimately reduces crop production and causes environmental pollution. Although sprinkler irrigation systems are usually designed so that the water application rate is less than the soil infiltration rate to avoid runoff, there are a growing number of sprinkler systems where runoff has become a serious problem. Large mobile single sprinklers (rainguns) which can irrigate large areas in a relatively short time are prone to severe runoff problems, because of the high application rates. Modern centre pivot and linear systems, which have now been designed to run at low energy saving pressures also produce high application rates and potential runoff. Most runoff problems are dealt with in the field on a trial and error basis. Being able to predict runoff under sprinkler irrigation would enable water application rate to be recommended and cultivation practices to be ‘designed’ rather than guessed on a trial and error basis in order to store surface water and avoid runoff. The objective of this study was to develop a mathematical model that can predict surface runoff from a small watershed area using sprinkler irrigation systems in either a stationary or moving condition. The objective was met in two ways: a mathematical model was developed from first principles called Overland Flow (OLF) and an existing model, KINEROS modified to EUROSEM, but designed for overland flow and soil erosion from hydrological watersheds was adapted to suit micro-catchment conditions for both stationary and moving sprinklers. Both models are based on kinematic wave theory. Both models were validated by laboratory and field experiments using stationary and moving sprinklers on simple plane and ridge and furrow cultivation practices. The validation results showed that the model predicts well the shape of the runoff hydrograph but also the key points for practical application. For example, time to start runoff, time to peak, peak flow rate, volume of runoff and time to end which are important when designing a cultivation practice in the field. The performance of the EUROSEM-KINEROS model was further evaluated by statistical techniques. There was good agreement between observed and model results. The EUROSEM-KINEROS model was also used to examine the best practical techniques to minimise the surface runoff. The application of this model to sprinkler irrigation design and management was also assessed. The evaluation results showed that the hydrograph parameters can be used to recommend water application rate, water application time and / or to design soil and water conservation structures to avoid critical situation in the field. Model validation for a moving sprinkler is recommended to be undertaken for different moving irrigators such as rainguns, centre pivot, side move systems and low energy precision application (LEPA) systems. Further investigations are also required to evaluate the use of the model to predict the effects of soil and water conservation techniques on runoff prevention for a cultivated land for different crops.
Open Access
Microbial diversity in contaminated soil
(2002-09) O'Flaherty, S. M.; Magan, Naresh; Hirsch, Penny
Little is known about soil population dynamics: how microbial communities are affected by environmental stress; whether they respond adversely, or adjust to it; what the extent and duration of these adjustments might be; which genera of bacteria are the most reliable indicators of soil quality. Inevitably, it is beyond the scope of this thesis to resolve all these issues, but it nonetheless sets out to address specific objectives which should cumulatively enhance our total understanding of the soil microbial environment. A three year study of abiotic environmental stress, using a distinctive multi-disciplinary methodology, examined how pseudomonad communities react to chronic metal pollution from sewage sludge. It deployed three profiling methods: population size, catabolic and genetic diversity, across three sequential sampling times, and processed large numbers of bacterial isolates to facilitate meaningful data analysis. This process required innovative methodologies. Efficient analysis of numerous pseudomonad isolates necessitated semi-automation, by adapting ERIC profiling to run on Genescan, a specialist application for analysing sequence data, hitherto unused to fingerprint soil isolates. Specialist computer programmes were designed to compare multiple isolates. A database system was built to gather ERIC profiles and convert them to generate standardised data for subsequent analysis. The main body of this thesis focuses on the interpretation of genetic relationships, largely derived from ERIC profiles, for which a series of programs was built. Alongside them, the BIOLOG™ technique is deployed to profile catabolic diversity and thus compare the function of environmental samples at different sampling times. Population composition, a third dimension, was examined using conventional plate counts. Initial findings that population diversity might be affected by metal stress were not, in the end, corroborated by the extended study. Both catabolic and population studies proved inconclusive, highlighting only subtle differences between metal-contaminated plots. Soil pseudomonads, in contrast to rhizobia, failed to prove sensitive indicators of low level metal contaminants.
Open Access
Natural disease resistance in strawberry fruit and Geraldton waxflower flowers
(2002) Terry, Leon Alexander; Joyce, Daryl C.
Antifungal activity against Botrytis cinerea and Cladosporium cladosporioides declined with increasing fruit maturity as shown by thin layer chromatography (TLC) bioassay. Preformed antifungal activity was also demonstrated in flower tissue. Decline in fruit antifungal compounds was correlated with a decline in natural disease resistance (NDR) against B. cinerea. Crude extracts of green stage I fruit contained at least two previously unreported preformed antifungal compounds (Rf = 0.44 and 0.37) that were not present in white and red stage fruit. These compounds were confirmed by TLC reagent sprays not to be phenolics or alkaloids. Positive reactions to Ehrlich’s reagent suggested that Rf = 0.37 was a teipene. The majority of antifungal activity was found in the achenes of green stage I fruit. However, antifungal activity was found in all tissue types (viz. pith, cortex, epidermis) of green stage I fruit. TLC bioassays showed that all fruit stages showed antifungal activity at the origin (Rf = 0.00). The approximate area of fungal inhibition at origin in green stage 1 fruit extracts was 90 and 70% greater than in white and red stages. TLC reagent sprays confirmed that antifungal compounds at origin contain phenolics. This is consistent with previously reported phenolic compounds in strawberry fruit that are inhibitory to B. cinerea. An investigation into the potential of enhancing NDR using different chemical (acibenzolar), biological (Aureobasidium pullulons) and physical (UV-C) elicitors was conducted with a view to developing an integrated pest management (EPM) strategy. The most promising results were achieved with pre-harvest treatments of the chemical plant activator acibenzolar. Seven glasshouse trials were conducted over a three year period. Preharvest application of acibenzolar (0.25 - 2.0 mg AI ml'1) were effective in suppressing grey mould on strawberry fruit harvested from winter grown plants. Conversely, acibenzolar was ineffective at suppressing grey mould on fruit harvested from summer grown plants. However, where acibenzolar was effective, disease development was delayed by as much as 2 days. This delay was equivalent to a 15-20% increase in shelf-life. If systemic acquired resistance and/or other inducible mechanisms are to be implemented as part of an IPM strategy for controlling B. cinerea more research is required on how environment and management factors affect the efficacy of elicitors such as acibenzolar. Geraldton waxflower is the most economically important native Australian cut flower export. Infection of Geraldton waxflower by B. cinerea can lead to unacceptable levels of flower abscission after harvest. Thus, an investigation was conducted into the nature and identities of constitutive antifungal compounds in imported Geraldton waxflower flower and leaf tissues. Antifungal activity against B. cinerea and C. cladosporioides was observed in both Geraldton waxflower leaf and flower tissue. Leaf tissue contained considerably less antifungal activity than flower tissue. Some antifungal compounds were common to the three different waxflower cultivars studied. Through TLC reagent sprays and NMR GC-MS spectra, these antifungal compounds were identified as the sesquiterpenes, globulol and grandinol. There were also at least two unidentified phenolics. Notwithstanding similarities in antifungal profiles, it was also evident from TLC bioassays that significant variations exist between different waxflower cultivars. Further work is required to fully characterise the preformed antifungals compounds found in strawberry and Gerladton waxflower tissues and to elucidate pathways involved in their biosynthesis. In addition, work is also required to look at the full spectrum of antifungal activity of these antifungal compounds. Such information will allow precise definition of the roles that these compounds may play in suppression of in strawberry and waxflower NDR against B. cinerea. In turn, this knowledge should enable the introduction of improved and/or novel IPM strategies that enhance levels of these compounds.
Open Access
Novel food applications of electronic nose technology for detection of spoilage fungi
(2001-10) Keshri, G.; Magan, Naresh
This work investigated the potential use of the electronic nose ( e-nose) for the rapid and early detection of fungal spoilage in intermediate moisture bakery products. Four xerophilic Eurotium spp., Penicillium chrysogenum and Wallemia sebi were grown on 2% wheat meal agar (WMA, 0.95 aw) at 25°C. Discrimination between the fungal species and the control media based on their volatile patterns was possible after 48h, using the Bloodhound BHl 14 e-nose. Volatile patterns produced by four Eurotium spp. and the Penicillium sp. were also investigated on WMA at different water activities (0.95, 0.90 and 0.85). Enzyme assays using p-nitrophenyl substrates were used as an indicator of spore germination and growth, and compared with volatile patterns and growth rates. Only three of the seven enzymes assayed were found to change significantly i.e. N-acetyl-P-D-glucosaminidase, a-D-galactosidase and P-Dglucosidase. Earlier detection and differentiation of the control blanks and the fungal species were achieved after 48h incubation, using the e-nose when compared to enzyme assays. In vitro study of volatile profiles from mycotoxigenic (Aspergillus flavus, A. ochraceus and W. sebi) and non-mycotoxigenic (A. niger and P. chrysogenum) fungi grown on WMA media demonstrated that differentiation of control blank media from the spoilage fungi was possible after 72h growth. Work on different mycotoxigenic and non-mycotoxigenic strains of Fusarium moniliforme and F. proliferatum showed that the e-nose could discriminate between the control blanks and the different strains after 48h growth. For all these studies the same three enzyme activities were found to be significant as in the previous work. Furthermore, the e-nose could detect fungal spoilage earlier than the enzyme assays. Volatile patterns produced by two Eurotium spp. and P. chrysogenum colonising a bread analogue modified to 0.95 aw at 25°C could be discriminated from the uninoculated bread after 40h incubation. This suggested that e-nose systems could be an earlier detection tool than enzyme assays. Furthermore, the same enzyme activities were found to be predominant as that observed for in vitro studies. E. chevalieri and P. chrysogenum were used to determine the limit of detection on a bread analogue (0.95 aw) using three inoculum concentrations (102 , 104 and 106 spores mr1 ). The initial spore concentration of 106 spores mr 1 treatments and the uninoculated bread analogue could be discriminated after 24h incubation. In another study, the volatile patterns produced by two Eurotium spp. and P. chrysogenum in the presence of potassium sorbate were measured. The uninoculated bread substrate and those colonised by the spoilage fungi could be discriminated after 48h growth. The study was repeated using calcium propionate and differentiation could be achieved only after 24h incubation. In the final study, volatile patterns produced by two Eurotium spp. and P. chrysogenum growing on natural bread substrate could be differentiated along with the uninoculated bread after 24h growth prior to any visible signs of growth. Overall, this study suggests that for the first time e-nose systems could be used to detect qualitative changes in volatile patterns for early and rapid detection of activity of the spoilage moulds in bakery products.