Wheat (Triticum aestivum L.) is one of the most important cereal crops in the world. In order to meet the food requirements of the current trend in population growth, enhancement in wheat production and yield are urgently needed. Water and temperature stress are major constraints to wheat production and subsequently food security in the context of climate change. Plant growth is affected by both above- and belowground environmental conditions and increasing atmospheric CO2 concentrations have been reported to enhance growth and yield of most agricultural crops. The responses of wheat roots and shoots to variations in soil water, temperature and CO2 concentration were studied in this research. X-ray Computed Tomography (X-ray CT) was used to visualise and quantify the behaviour of roots grown in soil under contrasting conditions for water content, temperature and CO2 concentration. Photosynthesis, stomatal conductance and transpiration were also measured to examine the shoot behaviour under the same environmental conditions. The results showed that total root volume (after 14 days) under the combined effect of elevated CO2 and temperature and mean root diameter for all experiments increased significantly with increasing water stress. However, total root volume decreased significantly under the effect of water stress independently and in combination with elevated CO2 and temperature. Mean root diameter also decreased significantly under repeated soil wetting and drying cycles. Total root volume and mean root diameter at 400 ppm CO2 growth was significantly greater than at 800 ppm CO2 growth at 14 days, while it was significantly lower at 30 days. Photosynthesis, stomatal conductance and transpiration decreased significantly by increasing water stress. Photosynthesis at 800 ppm CO2 was significantly greater than at 400 ppm CO2 while stomatal conductance and transpiration at 400 ppm CO2 were significantly greater. The elevated CO2 enhanced root architecture system and promoted photosynthesis. This research has demonstrated how the interacting variables of water, temperature and CO2 impact on the growth of wheat plants roots and shoots supporting the development of new management strategies for wheat to assist with the food security challenge under a changing environment.

Fusarium wilt of oil palm, caused by a soil-borne fungal pathogen Fusarium oxysporum f. sp. elaeidis (Foe), is a major problem to oil palm cultivation and palm oil yield in Africa, Asia, and parts of North America. There is currently a shortfall in palm oil to meet local and international demands. Thus, factors constraining maximum yield are critical to address. This research was done to find potential methods of controlling Foe in Ghana and if possible extended to other countries experiencing similar problems. Effective disease control will come from understanding the genetic variability of Foe, a combination of selection and release of resistant germplasm, and rapid detection of Foe. In-depth molecular fingerprinting via AFLP, SSR, ISSR as well as using the “housekeeping” genes (TEF and ITS) and effector proteins specifically SIX genes as molecular markers revealed genetic variations among different isolates of Foe from Africa (Ghana, Ivory Coast, DR Congo) and South America (Suriname) as shown in the various constructed phylogenetic trees in the study. This research has introduced improved measures to obtain resistant oil palm germplasm from the high local genetic diversity via pathogenicity studies. Pathogenicity assessment under green-house conditions through different inoculation techniques revealed four Foe isolates could cause infection in oil palm genotypes from Ghana and Malaysia. Effectors based on fourteen SIX genes were studied and primers with higher specificity designed for the LAMP technique for only Foe detection or diagnosis on site developed. Different LAMP primer sets were developed in this study to distinguish or discriminate only Fusarium oxysporum isolates from other pathogens. A P-450 cytochrome gene LAMP primer was also successfully developed in this research. Survey of the disease was conducted in four different oil palm plantation fields in Ghana. Tissue samples were collected from symptomatic oil palm trees neighbouring asymptomatic oil palm trees in fields of Ghana as part of the survey. All tissue samples from both symptomatic and asymptomatic oil palm tested positive for Foe infection via PCR. General observations in the oil palm plantations in Ghana showed that infection of Foe occurred in clusters among oil palm trees. Application of different control mechanisms against Foe with biological agents (Trichoderma sp.), chemical (sodium silicate pentahydrate - Na2O3Si.5H2O) or photochemical (Conventional UV or High Intensity Pulsed Polychromatic source) techniques all proved to be potential methods to suppress or totally inhibit Foe. Among the three Trichoderma sp. used in the study, Trichoderma harzianum (T3) was the most suppressive to the four Foe isolates, though the other two Trichoderma isolates, T. cerinum (T1) and T. atroviride (T2) showed potential as biological control agents (BCAs). The three different concentrations of Na2O3Si.5H2O test yielded varying results as increasing concentrations increased the percentage inhibition in all four Foe isolates used. The lethal dose for Foe spores with either a High Intensity Pulsed Polychromatic or Conventional UV sources was 60 KJ but oil palm pollen exposed to this dose did not germinate. Generally, the higher the dose of UV, the lower the percentage germination of the oil palm pollen in this study.

The Septoria tritici blotch disease (STB, pathogen Zymoseptoria tritici) is the most damaging foliar infection of wheat crops in Europe. Disease management strategies include cultivar resistance, disease escape strategy and fungicides. However, these strategies have failed to provide a complete protection of wheat crops. The STB tolerance is a complementary approach which aims to maintain yield in the presence of the symptoms. The tolerance of STB relies on plant physiology and source/sink balance: the sink demand (the grain growth) must be satisfied in spite of reduced source availability (photosynthetic capacity as affected by the STB symptoms on the leaves). The green canopy area, the senescence timing and the grain yield components are interesting potential sources of tolerance that were studied in this project. A data-mining study, one glasshouse experiment and two field experiments were carried out providing complementary insights on STB tolerance mechanisms. The genotype/environment interaction effects on tolerance traits were investigated for two seasons five locations/nine cultivars datasets. The nitrogen nutrition and metabolism of four doubled-haploid (DH) lines contrasting for STB tolerance were examined in a controlled glasshouse experiment at UMR ECOSYS (INRA,AgroParisTech) Grignon, France. The source/sink balance of six DH lines contrasting for STB tolerance was also examined according to their responses to a spikelet removal treatment, applied in a field experiment in Hereford, UK. Finally, a field experiment with two fungicide regimes (full disease control and non-target (STB) disease control) probed the STB tolerance of six modern UK winter wheat cultivars in Leicestershire, UK. The main objective was to verify identified potential STB tolerance traits in commercial cultivars. Putative STB tolerance traits have been identified such as the early heading date, the low degree of grain-source availability of healthy crops during the grain filling phase, the vertical canopy distribution favouring a relatively larger flag-leaf. Results showed these traits might be selectable in wheat breeding without a trade-off with the potential yield. Finally, the project also discussed the need for alternative STB tolerance quantification methods, as well as the importance of environmental variations which have to be taken into account to study genetic variation in tolerance, but which could also be used to discriminate tolerant environment.

Global population is expected to rise to 9 billion in another 40 years and changing climatic conditions coupled with various other abiotic and biotic stress factor have posed challenges for crop cultivars globally. Cereals like wheat, rice and maize have a central place in the human diet and require immediate attention in terms of improving yield in order to satiate the global food demand. This demand can be fulfilled by improving crop yield by exploiting natural variation in modern wheat by conventional breeding method like wheat ancestral introgression. One of the key traits that can be exploited such hybrids would be photosynthesis, ongoing debate and researcher have suggested that improving photosynthesis would be an attempt towards enhancing biomass and yield in crops like wheat and rice. In this project two different approaches were used to create interspecific hybrid, these hybrid were amphidiploids, which were created by chromosome doubling of haploid chromosome from wheat and wild relatives of wheat. First, a set of wild relatives were crossed bread wheat such as Highbury, Paragon, Chinese spring mutant, Chinese spring mutant and Pavon 76) and the amphidiploids created through these crosses where exploited for photosynthetic traits and other related physiological traits under glasshouse conditions. Second, amphidiploids created by cross using a wild relative Thinopyrum bessarabicum with durum wheat and tested in field conditions in India. Techniques like infra-red gas exchange, chlorophyll were used to assess photosynthetic performance in the glasshouse in optimal conditions and in the field under challenging environmental conditions. Along with the amphidiploids in the field conditions, a panel of 30 Indian genotypes were tested for natural variation in photosynthesis in field conditions. Almost similar set Indian genotypes were tested in glasshouse conditions in UK, to exploit the natural variation in photosynthesis. Initially, these Indian genotypes and amphidiploids grown in glasshouse as well as field conditions were screened for variation in photosynthesis. Promising lines derived from these instantaneous measurements were investigated for detailed photosynthetic measurements to understand the underlying biochemical mechanism that regulates photosynthesis and also were investigated leaf morphological and anatomical features for increased photosynthetic capacity. Here we show natural variation in photosynthesis in the amphidiploid population in both field and glasshouse conditions and range parameters that regulates photosynthetic rate in introgressed lines.

Fusarium head blight (FHB) is a devastating fungal disease of wheat and small grain cereals worldwide, causing yield losses, reducing grain quality, and leading to mycotoxin contamination of grain. Breeding for resistance to FHB by conventional selection is feasible, but the main challenge is to identify new genotypic variations and increase resistance by pyramiding multiple traits and quantitative trait loci (QTL). The aim of this work was to determine the physiological traits related to passive resistance and identify QTL conferring active resistance to the FHB. Double haploid (DH) wheat lines were ground inoculated in field experiments to enable passive disease traits to be expressed under natural rainfall and artificially misted conditions whilst ear inoculated glasshouse experiments were used to test if any of the assessed traits were associated with genetic resistance. Spikelet density was identified as a potential ear trait in the field contributing consistently to increased FHB progression. Flag leaf length and tiller number influencing pathogen dispersal and spread within the canopy were the most consistently significant traits, positively related to FHB development indicating a potential underlying genetic linkage which was not confirmed in subsequent QTL analysis. Instead these traits were associated with increased susceptibility and were negatively affecting any passive resistance mechanisms such as disease escape. To identify QTLs for canopy and ear traits, and resistance to FHB and Septoria tritici blotch (STB), a DH population of 107 lines was evaluated in two Fusarium and Microdochium ground inoculated, artificially misted and two Microdochium seed inoculated, non-misted experiments. A coinciding QTL for AUDPC and bleaching was found on chromosome 7D and a second QTL on 2B. An overlapping QTL for FHB lesions was detected on 5B and a second QTL on 4A conferring resistance to M. majus and fungal biomass accumulation in grain and in anthers. F .graminearum DNA in grain and anthers was conferred by a distinct QTL on 4B. QTLs for resistance to accumulation of deoxynivalenol (DON) and zearalenone (ZON) were detected on 5A and 6B, respectively. This study is the first to report the coexistence of resistance QTL for fungal biomass accumulation in grain and anthers and novel QTL for ZON in wheat. A QTLs for STB was found on chromosome 2A, for awns length on 5A. A QTL for flag leaf length on 3A and coincided QTLs for flag leaf length and flag leaf width on 7B failed to coincide with disease traits suggesting that the identified canopy traits were not genetically linked with disease but of rather epidemiological significance. The study identified separate QTLs conferring resistance to different Fusarium and Microdochium species indicating that resistance is distinctly regulated and likely to be species specific. To identify novel ear traits and determine the role of anthers and pollen in resistance to initial infection (Type I) or FHB susceptibility, ear inoculated glasshouse experiments using selected wheat genotypes and a point inoculated growth room experiment using fertile barley line (cv. Golden Promise) and cytoplasmic male sterile (CMS) lines (HvMS1 and HvDYT1) were conducted. The most consistent traits in glasshouse experiment were ear length, number of spikelets per ear and anther extrusion. Sugar concentrations in wheat anthers was quantified to observe the potential nutritional role played by different sugars for spore germination and infection by F. graminearium. Results from in vitro anther-fungal bioassays indicated that fungal spores utilize sucrose and fructose during germination and glucose for growth and infection. The role of anthers and pollen and possible biochemical substrate stimulating spore germination and fungal growth in wheat and barley in addition to Arabidopsis wild ecotypes (Columbia and Landsberg erecta) and mutants ABORTED MICROSPORES (AMS) producing non-viable pollen, MALE STERILITY1 (MS1) producing no pollen and MS35 non-dehiscing anther was investigated in a series of bioassays. CMS lines with infertile anthers were more resistant to FHB infection than wild type (WT). Spore germination was significantly reduced in the presence of wheat anthers containing no pollen while barley CMS line HvMS1 and HvDYT1 with sterile anthers also showed reduced spores germination. In Arabidopsis WT spore germination was significantly higher in the presence of fertile anthers compared to the mutants MS1 and MS35. Releasing MS35 pollen significantly increased spore germination. Reduction in spore germination was observed in all heat stressed replicates, irrespective of the anther and pollen presence or absence. These results indicate that the presence of fertile anthers and subsequent release of pollen are an important part of the infection pathway and of susceptibility to FHB while heat stress can destroy any substance in anthers and pollen stimulating Fusarium spores in-vitro. The current research findings show that FHB resistance type I (resistance to initial infection), type II (resistance to spread) and type III (resistance to mycotoxin accumulation) in wheat is conferred by a combination of active and passive resistance traits whereas active resistance is also associated with alleles determining the morphological, physiological and biochemical plant characteristics. Moreover, the expression of active and passive resistance is highly influenced by the environmental interactions, inoculum source, pathogen species and virulence under field conditions. Consequently, selection for desirable canopy and ear morphology traits conferring improved type I resistance in combination with cultivars with substantial levels of type II resistance can improve the overall FHB resistance in wheat.

Wheat is one of the most widely consumed staple crops in the world including India and its demand is increasing with increasing population. Increased grain yield (GY) has been associated with increased use of nitrogen (N) fertilizers which represent a significant environmental and production cost. Developing cultivars which have higher grain yield but use N efficiently may allow reduced fertilizer N inputs. The objectives of this study were to: (i) quantify the genetic variability in N use-efficiency (grain dry matter (DM) yield per unit N available from soil and fertilizer, NUE) in a panel of modern Indian wheat cultivars and find new genetic variation in a panel of amphidiploids produced by crossing hexaploid bread wheat with wild wheat relatives and (ii) identify traits and understand physiological mechanisms determining improved NUE to exploit for development of new N efficient cultivars. Thirty Indian elite bread wheat cultivars and 18 amphidiploid lines along with their five respective bread wheat parents were tested under high N (HN) and low N (LN) conditions in two years in field experiments at Agharkar Research Institute, Pune, India (2013 and 2014) and in glasshouse experiments at Nottingham University, UK, (2015 and 2016), respectively. Detailed growth analysis was conducted including GY, above-ground dry matter (AGDM), DM and N partitioning at anthesis and at harvest along with N remobilization efficiency (NRE) in the field experiment. Senescence kinetics of the flag-leaf were assessed from a visual score weekly from anthesis to complete canopy senescence in both sets of experiments. Physiological traits were assessed including flag-leaf light-saturated photosynthetic rate (Amax) under HN conditions in the field experiment and under both HN and LN conditions in glasshouse experiment. Flag-leaf relative chlorophyll content (SPAD) under HN and LN conditions was measured in both experiments; and Normalized Difference Vegetative Index (NDVI) under HN and LN conditions in field experiment. 2D seedling root phenotyping was carried out on subset of 12 genotypes selected based on contrasting performance under LN conditions from both the field and glasshouse experiments. In field experiments, GY was reduced under low N (LN) conditions on average by 1.46 t ha−1 (28%). Crop above-ground N-uptake at harvest on average was reduced from 16.2 kg N ha−1 under HN to 8.5 kg N ha−1 under LN conditions while N-utilization efficiency (grain DM yield per unit above-ground N uptake at harvest; NUtE) increased from 32.7 to 44.6 g DM g−1 N. Significant N × genotype level interaction was observed for GY, N uptake at harvest and NUtE. Overall genetic variability in GY and NUE (which ranged from 15.6 - 23.7 g DM g−1 N under LN; P<0.001) related mainly to differences in N uptake rather than NUtE. Overall, cultivars ranged significantly at anthesis in N accumulation in the flag-leaf N (1.1 -2.2 g N m−2 at HN and 0.5-1.0 g N m−2 at LN), the stem and remaining leaf with sheath (5.78-11.97 at HN and 3.61- 6.33 g N m−2 at LN) (P=0.01), and the ear (2.91-6.13 at HN and 2.06-4.23 g N m−2 at LN) (P<0.001). Cultivars ranged in N partitioning index (proportion of above-ground N in the crop component, NPI) at anthesis for the flag-leaf from 0.08 to 0.16 at HN and 0.07 to 0.13 at LN (P< 0.001); and for the stem-and remaining leaf with sheath from 0.54 to 0.68 at HN and from 0.52 to 0.65 at LN (P<0.001) and for ear from 0.21 to 0.34 at HN and from 0.28 to 0.41 at LN (P<0.001). The post-anthesis NRE was positively associated with the duration of flag-leaf senescence amongst cultivars under LN. Genetic variation in grain yield and grain N% (through N dilution effects) appeared to be mainly influenced by pre-anthesis N accumulation rather than post-anthesis N remobilization under LN conditions. Under N stress conditions, there was evidence that NRE was a determinant of genetic variation in grain N%. Flag-leaf Amax was positively associated with AGDM (P=0.02), GY (P=0.14), and specific leaf N at anthesis (P=0.046). Flag-leaf onset (VS.OnsetRP) and end (VS.EndRP) of senescence was positively associated with GY, AGDM and NRE in both N treatments. In the glasshouse experiments, out of 18 amphidiploid lines, two lines under HN and three lines under LN conditions showed transgressive segregation (TS) above the bread wheat parent for pre-anthesis Amax and 12 lines under HN and 7 lines under LN conditions showed TS for post-anthesis Amax. In addition, higher expression than the bread wheat parent was observed for Thinopyrum turcicum P208/201 x Chinese Spring Eup 94 under HN conditions for GY and for Thinopyrum turcicum P208/201 x Chinese Spring Eup 94, Secale anatolicum P208/142 x Highbury and Secale anatolicum P208/141 x Chinese Spring Eup 94 under HN conditions for AGDM showing potential to exploit these genotypes for wide crossing for NUE wheat breeding. Seedling root architectural traits including seminal root number per plant showed association with field and glasshouse GY and NUE related traits in HN and LN conditions. Overall amphidiploids showed evidence for increased root depth than bread wheat cultivars in the hydroponics seedling platform under both HN and LN conditions. In summary: • N-use efficiency in thirty Indian wheat cultivars in the field was correlated with onset of flag-leaf senescence under high N and low N conditions and senescence timing was correlated with N accumulation at anthesis. • Yield response to N limitation of 30 wheat cultivars was associated with responses in N uptake at anthesis under both N conditions. • The grain yield in N stressed crops for the 30 cultivars was limited by post-anthesis source capacity. • Three amphidiploids lines (Thinopyrum turcicum P208/201 x Chinese Spring Eup 94, Secale anatolicum P208/142 x Highbury and Secale anatolicum P208/141 x Chinese Spring Eup 94) in glasshouse conditions showed higher flag-leaf photosynthesis rate and prolonged flag leaf green area than their recurrent parents. • The 2D seedling RSAT study showed seminal root number was correlated amongst 12 Indian wheat cultivars and amphidiploids with grain yield per shoot under high and low N conditions.

Brassica napus, oilseed rape (OSR), is a worldwide cultivated crop belonging to the family Brassicaceae, broadly used in crop rotations with cereals. Production is focused on oil for human consumption, biodiesel and feedstock. OSR has undergone intensive breeding for optimization of oil content, disease resistance and augmentation of yields, and today is considered one of the most profitable crops. Nonetheless, oilseed rape is the primary host for the necrotrophic soil-borne pathogen Rhizoctonia solani anastomosis group (AG) 2-1. Infection of seedlings causes damping off disease and decreases crop establishment and yields. AG 2-1 is the most prevalent AG of R. solani in wheat fields in the UK. Currently there is no OSR germplasm resistant to R. solani AG 2-1. Available control methods include cultural practices and chemical seed treatments, which aim to postpone the infection and hence improve crop establishment. Changes in agronomic practices and crop management, including choice of cultivars, tillage, application of fertilisers and pesticides, mean that there is a danger of future outbreaks of diseases that in the past were not considered as major problem. This includes R. solani AG 2-1 which can infect other rotational crops as well and due to its saprophytic nature remains in the fields for years. The aim of the PhD was to elucidate interactions between R. solani AG 2-1 and B. napus, by identifying potential resistant traits and understanding how the pathogen counteracts OSR plant defences. The first objective was to develop and compare different high-throughput screening methods that could be used for the phenotyping of OSR germplasm interactions with R. solani AG 2-1. Four methods were developed and compared: (1) nutrient media plates, (2) compost trays, (3) light expanded clay aggregate (LECA) trays and (4) a hydroponic pouch and wick system. Inoculation of LECA was the most suitable method for screening disease caused by AG 2-1 to OSR germplasm, because it allowed the detection of differences in disease severity between the tested OSR genotypes 5 days post infection (dpi) and also to conduct measurements in whole plants. The second objective was to identify any sources of disease resistance by screening a diversity of OSR germplasm. To start the screening, I selected randomly germplasm from commercial cultivars and parental lines of mapping populations that was available in our seed bank. Overall, the germplasm tested consisted of commercial cultivars, genotypes from diversity sets and a mapping population. All genotypes tested appeared to be susceptible to AG 2-1 infection as shown by high disease levels, reduced emergence and survival. Additionally, I tested if any induced defence responses from exposure to disease could be inherited in the next generation through an epigenetic stress response. However, all progeny plants were also highly susceptible indicating that there was no evidence for transgenerational induction of resistance in this system. The third objective was to gain insight into OSR plant defences when exposed to a combination of attacking organisms, as this often occurs in real field situations. I investigated the role of M. persicae infestation on OSR susceptibility to R. solani AG 2-1. There was no effect of AG 2-1 infection on aphid performance. However, M. persicae infestation resulted in significantly more disease symptoms in B. napus cv. ‘Canard’ plants although there were no significant differences in the amount of fungal DNA. Marker genes LOX3 and MYC2 had an augmented expression under AG 2-1 treatment but were downregulated in plants exposed to both aphids and pathogen. Hence, it appears that aphid infestation induced changes in the jasmonic acid (JA) signalling pathway, which resulted in the increased susceptibility to AG 2-1. In conclusion, the present work provided a new high-throughput screening method suitable to phenotype disease by AG 2-1 in the early seedling stage within a short time period. Unfortunately, the current results confirm previous studies indicating that AG 2-1 is an extremely aggressive isolate to OSR germplasm that lacks genetic resistance. Nonetheless, the observed differences between the germplasm tested in the present work suggest that there are potential tolerant traits. For the first time, the current work provided evidence that M. persicae infestation can negatively affect plant defences against R. solani AG 2-1, through suppression of genes involved in JA signalling. Additionally, it was demonstrated that R. solani AG 2-1 induces the activation of defence mechanism related to both JA and salicylic acid (SA) pathways. Future studies aiming to identify resistant/tolerant traits should screen wider Brassica germplasm, including wild species. Additionally, it will be particularly interesting to explore how R. solani overcomes OSR defences by examining the expression of a broader array of genes involved in plant defence mechanisms.

The practice of gardening and growing-your-own (GYO) produce in urban areas, has been associated with many potential benefits to health from increased fruit and vegetable consumption and exercise, but also health risks arising from exposure to potentially toxic elements (such as cadmium: Cd, and lead: Pb) in urban soils. However, the potential health benefits of gardening are currently overlooked by authorities during assessments of contaminated land, which may result in access to urban gardens and allotments being incorrectly restricted or removed because of concerns over the impact to human health. The trade-off between health benefits and risks is investigated in this thesis through: the sampling and analysis of the properties of allotment soils (chapter 2); a comparison of plant uptake models (chapter 3) verified using a pot experiment (chapter 4), and a questionnaire survey investigating the effect of gardeners’ routines on benefits and risks (chapter 5). The different areas of study are combined in the creation of a model framework developed to estimate health benefits and risks attributable to urban gardening (chapter 6). A total of 149 allotment plots were sampled across the city of Nottingham and analysed in the laboratory for trace element concentrations by ICP MS. Concentrations of lead (Pb) in top-soils exceeded the category 4 screening level of 84 mg Pb kg-1 dw in most plots (n=129), with a median concentration across all plots of 214 mg Pb kg-1 dw. However, other elemental concentrations (As, Cd, Cr) were below the respective C4SLs for an allotment land-use and unlikely to pose health risks. In comparison, analysis of the results of a questionnaire survey of 120 gardeners’ routines, suggested that gardening more regularly in autumn and winter was positively correlated with categories of increased fruit and vegetable consumption and exercise (one-way ANOVA; p < 0.05). Furthermore, gardeners over the age of 45 scored significantly better in the physical health (but not the mental health) categories of the SF 36 v 2 questionnaire compared to standardised scores when results were adjusted for age and gender (Table 5.9). Health benefits and risks were combined using a prototype Bayesian Network (BN) model developed according to the principles of CLEA (Contaminated Land Exposure Assessment model). Health outcomes from benefits (e.g. fruit and vegetable consumption) and risks (e.g. lead toxicity) were derived using a sub-model; requiring odds and hazard ratio’s for the outcomes of disease. The model predictions suggested that for the study population, whilst there were some benefits attributable to urban gardening, these appeared to be outweighed by health risks from potential exposure to Pb. Further work is required to confirm or refute this finding and to validate and improve the BN model. The study also highlights the importance of considering health benefits of gardening in risk assessment in future for urban gardeners. Future work should also consider weaknesses highlighted in the use of the CLEA model to predict health risks for gardeners, especially in the prediction of plant uptake of toxic elements, and the limited data availability describing the toxic effects of chemicals exceeding a threshold value which may or may not result in SPOSH.

Winter wheat (Triticum aestivum L.) is one of the mostly widely grown arable crops worldwide, with a total annual global production of approximately 716 million tonnes. In the UK, around 14.5 million tonnes of wheat is produced annually on roughly 1.8 million hectares of land; however, 15-30% of this annual wheat yield production is lost to drought. Two field experiments were conducted in 2013-14 and 2014-15 to characterise a doubled-haploid (DH) population of 94 lines derived from a cross between the winter wheat cultivars, Rialto and Savannah, at the University of Nottingham Sutton Bonington Campus, UK (52o 50' N, 1o 15' W). This population was selected due to the genetic variation observed in previous field experiments in stay-green traits under drought and nitrogen stress in the UK and France (Foulkes et al., unpublished). A shovelomics methodology was developed for phenotyping wheat crown root traits of the mapping population and validation on soil core samples (extraction of roots by washing and root scanning using WinRHIZO software) was carried out on a subset of 14 DH lines and the two parents. In addition, two 50-cm soil column glasshouse experiments examining the two parental genotypes and the subset of 14 Rialto x Savannah DH population lines, and one 100 cm soil column glasshouse experiment examining the two parental genotypes and two Rialto x Savannah DH lines using micro-computed tomography (μCT) scanning, were carried out under well-watered and drought conditions. Two further glasshouse experiments were carried out to quantify root anatomical traits on the two parental genotypes under well-watered and drought conditions. The main objectives were to quantify genetic variation in root traits and associations with water uptake and drought tolerance in the Rialto x Savannah doubled-haploid population, to quantify mechanisms underlying associations between root traits and water capture and drought tolerance and to identify quantitative trait loci (QTL) associated with root traits and drought tolerance through genetic analysis in the Rialto x Savannah DH population. In the field experiments, drought reduced grain yield by 16.7% in 2014 and 14.9% in 2015. Amongst the DH lines, genetic variation for crown root angle, roots plant-1, roots shoot-1 and length was observed (p < 0.05). Under unirrigated conditions, root length density (RLD) at depth (40-60 cm) was positively associated with crown root angle and crown roots shoot-1 in 2014 and 2015. RLD at depth was also positively correlated with grain yield. Amongst the 94 R x S DH lines, crown root angle (greater angle = steeper root) and crown roots shoot-1 were positively associated with post-anthesis canopy stay-green as indicated by the Normalised Difference Vegetation Index (NDVI) spectral reflectance index and grain yield under unirrigated conditions. Later onset and end of flag-leaf senescence were associated with increased grain yield in 2014, but not in 2015. In the x-ray μCT soil column experiment, there were positive relationships amongst genotypes between steeper crown root angle at 5, 10 and 15 cm depths measured using μCT and RLD at 60-80 cm depth measured directly (WinRHIZO root scanning) under drought, but negative relationships under well-watered conditions. RLD at 60-80 cm was associated with water uptake and number of grains plant 1 under drought. There were positive associations between the total root length plant-1 measured using μCT and direct measurement of this trait (WinRHIZO root scanning) and between μCT root number and direct measurement of RLD in each soil horizon. In addition, there were associations between root angle in the μCT soil column experiment and crown root angle in the field measured using shovelomics techniques. Under drought, root cortical aerenchyma, the ratio of total stele area: total cortical area and cortical cell size were found to increase and total cortical area, cortical cell file number, xylem area and metaxylem area to decrease in the parental lines. Each of these anatomical traits was related to improved water uptake under drought. This indicated that root traits that may reduce the metabolic cost of soil exploration, or decrease water loss, may improve the acquisition of limiting soil resources under water-stressed conditions. For the QTL analysis in the Rialto x Savannah DH population, co-locating QTL for crown root angle and NDVI, HI and AGDM were identified under irrigated or unirrigated conditions in individual years on chromosomes 3B and 7A. QTL for stay green traits under both irrigated and unirrigated conditions were identified on chromosome 7D. Overall, these results indicated the potential for designing a winter wheat ideotype to enhance drought tolerance under UK drought with steeper crown root angle, increased crown roots shoot-1 and anatomical traits related to decreased metabolic cost, all of which increase RLD at depth, thereby improving water uptake at depth. Results from the shovelomics crown root assessments indicated scope for high-throughput field root phenotyping to quantify responses of crown root traits under drought and validate the relationship with root traits at depth, and identify QTL and candidate genes linked to these traits.

Alopecurus myosuroides, a problematic weed of UK winter cereals, is predominantly controlled by post-emergent herbicides with ALS and ACCase modes of action (MOA). Evolved resistance to these MOA - endowed by the mechanisms of targetsite (TSR) and/or enhanced metabolism (EMR) – threatens the sustainable production of winter cereals in the UK. This project aims to establish the frequency of ALS and ACCase resistance in UK populations of A. myosuroides and the factors that drive its evolution. From a 2011 survey of 92 UK A. myosuroides populations, mesosulfuron-methyl + iodosulfuron-methyl-sodium (ALS) resistance was confirmed in 81 populations; all 92 populations exhibited clodinofop-propargyl (ACCase) resistance. To understand how management affects resistance evolution, seventeen populations from the 2011 survey were resampled (2012–2014) so that estimated frequencies of phenotypic resistance, TSR and EMR could be compared to weed management histories. Fields in which spring crops were more frequently planted possessed A. myosuroides that exhibited lower levels of phenotypic resistance to both ALS and ACCase MOA. A simulation model was developed to describe A. myosuroides herbicide resistance evolution. However, this model could not be validated when parameterized with resistance and management data collected from the UK. In the 2011 survey, homozygous Pro-197-Thr ALS TSR mutations were absent. Phenotyping, germination, and genotyping experiments of plants from controlled heterozygous Pro-197-Thr crosses confirmed that there is a lethality associated with homozygous Pro-197-Thr mutations. To test the hypothesis that preexisting ACCase EMR increases the rate of ALS EMR selection, four A. myosuroides populations – three with ACCase EMR and one without - were selected over two generations with ALS herbicide. From dose-response analyses of survival, the three populations with ACCase EMR exhibited significant increases in ED50 values after selection, whereas the population without ACCase EMR did not.