Many species of moths within the family Noctuidae are significant agricultural pests. Specific floral volatiles are attractive to both male and female Noctuidae and may be used to as attractants in crop protection. For the first time the following research compares two types of floral volatile blends - those that mimic natural floral odours and those that are artifical odour blends ('super-blends'). In wind tunnel bioassays and field trials in two diverse geographic locations (Argentina and the United Kingdom) a range of noctuid moth species that are considered crop pests were found to be attracted to both types of the floral odour blends. However, a 'super-blend' containing phenylacetaldehyde, salicylaldehyde, methyl 2-methoxybenzoate, linalool, and limonene (in a 10 : 4 : 2 : 2 : 1 ratio) was found to be the most effective general attractant across the following species: Helicoverpa armigera and gelotopoeon, Heliothis zea, Spodoptera frugiperda, and Autographa gamma suggesting that these compounds are universal cues to this family of moths when searching for flowers. Further behavioural bioassays found that the physiological state of the insect had an important effect on its behavioural response to the floral odour super-blend. Bioassays carried out on H. armigera revealed that gravid insects were significantly less likely compared to virgin insects to make contact with an odour blend baited lure. In addition, insects provided with sucrose solution were significantly less likely to make contact with the odour source compared to starved insects or insects only provided with water. This is the first time this affect has been seen in this species and may have important implications for using these types of floral odours for crop protection. Investigations into the most effective trap for capturing Noctuidae found that a homemade bucket and water trap or funnel and sleeve traps were significantly more effective than UniTraps or sticky traps. During the field trials large numbers of nontarget insects were also captured, including beneficial insects and pest species. By using green coloured traps captures of beneficial hymenoptera (Syrphidae and Apoidea) were significantly reduced. Taken together, the current findings provide insights into how Noctuid moths interact with host odour cues and how they may be used in developing pest management techniques.

The case for improving Phosphorus-Use Efficiency in crops is widely recognised. Although much is known about the underlying molecular and regulatory mechanisms, improvements have been hampered by the extreme complexity of phosphorus (P) dynamics in soil and plants (across all physical scales), including its soil chemistry and uptake, distribution and deficiency responses in plants. The urgency and direction of phosphate research is also being driven by the availability of finite P stocks to farmers and reducing environmental hazards. Thus, systems approaches become essential to identify the most potent (combinations of) target genes for improving phosphate uptake and utilisation in crops. This study has applied these approaches with the aim of increasing understanding of the regulation of phosphate uptake at three separate spatial scales, primarily in rice, but also in Arabidopsis. The first and major part of this study has focused on the cell scale, wherein novel mathematical models for molecular regulation of phosphate acquisition have been developed. Owing to the sparsity of the data, advanced techniques for parameter fitting were employed, which resulted in an original model, which accurately reflected the profiles of all the genes apart from PHO2. It was clear that miR399-mediated degradation was insufficient to explain the apparent early reduction in PHO2 mRNA levels. Five hypotheses were explored mathematically, of which the most plausible is that there is a phosphate-sensitive transcriptional repressor (PsTR) of PHO2 mRNA synthesis. To support this hypothesis, mRNA was extracted from phosphate-starved and untreated roots over a short, 12-hour time course. Quantitative Polymerase Chain Reactions (qPCR) of PHO2 mRNA both confirmed the early decline predicted by the hypothesis and also revealed a temporary restoration of mRNA levels, which points to PHO2 (a type-2 ubiquitin ligase) regulating its own transcript levels. Sensitivity analysis of these models indicates that the utilisation rate of cytosolic phosphate is the biggest influence on this system. Output from simulations with the original and PsTR models qualitatively reproduced the phenotypes of various published phosphate-research papers, with the exception of RNASEQ data in which phosphate-starved rice roots were resupplied with phosphate. In this instance, the observed rapid drop in mRNA levels for PHO2 and IPS1 were incorrectly predicted, pointing to one or more other regulatory mechanisms not represented in these models. The IPS1 gene encodes a long non-coding RNA that has a poly-A tail. Its RNA also binds to miR399 and accumulates to extremely high levels in plant roots during phosphate stress. A sudden loss of IPS1 would release the bound miR399 causing the observed rapid loss of PHO2 mRNA. The observed IPS1 profile can be explained by either the gene having a “super-promotor” that is capable of extremely high RNA synthesis under low phosphate conditions, or the transcript being protected from degradation by phosphate-sensitive RNA-binding proteins. Informatics analyses favour the latter and a revised model incorporating RNA protection was found to have parameters for IPS1 synthesis that are similar to those normally used in modelling gene regulation. The analyses also point to PUMILIO proteins playing this role. The second part of this work has explored the role of tissue geometry in determining root phosphate levels and flux. Multi-cellular vertex-based models of published Arabidopsis and rice root cross-sections were produced using CellSeT, into which equations for phosphate uptake, flux and utilistion were embedded using OpenAlea. Simulations suggest that Arabidopsis trichoblasts have lower cytosolic phosphate levels than neighbouring epidermal cells, because they have a larger area through which phosphate flows into the inner tissues. This implies that trichoblasts are more sensitive to phosphate stress and reduced phosphate levels could therefore be part of the trigger for initiating root-hair growth. Adding root hairs of varying lengths into this geometry shows that a hair does not have to grow much before the phosphate levels in this trichoblast exceeds those in the neighbouring cells and that phosphate flows to them. This potentially suppresses root-hair formation in nearby trichoblasts. The rice simulations show that aerenchyma dramatically reduces cytosolic phosphate in surrounding cells and point to a role for lacunae in rapid uptake of phosphate, without the need for large water fluxes. Alongside aerenchyma, a higher proportion of fluid-filled lacunae could be a desirable trait for improving nutrient-uptake efficiency. At the whole-plant scale for the third part of this work, a time-course dataset has been generated to record the effect of phosphate starvation over 21 days on the uptake dynamics of eleven other macro- and micro-nutrients. This dataset will be of use in future systems studies of nutrient uptake and interactions.

The baobab tree (Adansonia digitata L.), with more than 300 uses and commercial value in EU and US, has been identified as one of the most important edible savannah trees to be conserved, domesticated and valorised in Africa. A decline in baobab populations due to overexploitation and/or changes in climate could have a significant negative effect on African livelihoods. Therefore, it is important to determine potential strategies for conservation and cultivation. The present and potential future distributions of the baobab tree were studied using Maxent niche modelling framework. And, in order to contribute to the selection of superior materials for cultivation, fruit morphology was studied in situ (in Malawi and Mali) while leaf and seedling morphology were studied in situ (in Benin and Malawi) and in a greenhouse experiment. Maxent modelling suggests that predicted changes in climate will have a negative effect on baobab tree distribution in Africa: only a percentage of the present distribution was predicted to be suitable in the future. Some countries were found not to have any suitable habitats for the baobab tree in the future. Several conservation strategies are recommended, such as in situ conservation in Protected Areas; ex situ conservation in Seed Banks and conservation through ‘sustainable utilisation’. Modelling results also showed that the baobab tree could be widely cultivated in most countries in south-eastern Africa and in the Sudano-Sahelian zone of West Africa. India, north-west Australia, Madagascar, north-east Brazil and Mexico could be other suitable places for cultivating the baobab tree outside Africa. Although results from modelling should be validated with in situ seedling experiments, there seems to be potential for the wide cultivation of this species. Significant differences in leaf, fruit and seedling morphology were observed between Benin, Mali and Malawi and also within each country. While some characteristics were correlated with environmental differences between study sites, others might be genetically determined. It seems that genetic and physiological effects play a role in baobab fruit, leaf and seedling morphology. Thus, there is room for selecting high quality baobab planting materials

The aim of the thesis is to contribute to our understanding of how individuals in developing countries cope when faced with environmental risks. These themes are explored while focusing on small-scale farming communities in Wellawaya, south-east Sri Lanka, that are heterogeneously exposed to a particular environmental risk, namely the Human-Elephant Conflict (HEC). First, we examine the strategies which households within farming communities use to cope with exposure to the HEC. We conduct an individual-level household survey of 468 randomly-sampled households across sixteen farming communities which are highly exposed to the HEC. Our unique, cross-sectional data provides a snapshot of the coping strategies which they employ. We find that households which experience greater HEC-related damage are more likely to: rely to a greater extent on non-farm income; cultivate less land in each of the two cropping seasons; and have children who engage in non-farm employment. Next, we investigate the effect of interdependent risk exposure on individuals’ ex-post sharing behaviour. By interdependence, we refer to when an individual’s choice over their own risk exposure directly impacts the risk exposure of another individual. The results from our lab-type risk-and-sharing game suggest that individuals positively reciprocate when another individual’s decision causes them to face lower risk exposure, but do not negatively reciprocate when another individual’s decision causes them to face higher risk exposure. A risk-averse individual who has agency over another’s risk exposure is more likely to share ex-post payoffs, while a relatively risk-tolerant individual does not. Our results suggest that risk attitudes and the balance of power within communities need to be considered by policymakers involved in the design of community-driven development initiatives. Finally, we adopt a mixed methods approach to investigating how heterogeneity in individual returns to a public good and beneficiaries’/contributors’ risk attitudes affect public good contributions. We examine this in the context of Sri Lanka’s HEC and conduct a one-shot, framed, lab-in-the-field, public goods experiment (PGG) which reveals subjects’ contribution preferences when returns from the public good are asymmetric. Subjects also answer a hypothetical contribution question (HCQ) stating their time contributions to the construction of the public good. We find that heterogeneity in individual returns does not have a negative effect on contribution behaviour. Risk-aversion in the PGG, in this context, motivates people to engage in collective risk mitigation. The mixed method approach provides an encouraging and balanced account of communities’ potential engagement in HEC-mitigating public goods provision.

Rhizobia are frequently used in the agriculture sector to enhance legume growth and improve soil fertility. There is growing interest in utilizing biological nitrogen fixation as a means of increasing the potential for sustainable intensification of food production whilst simultaneously reducing environmental damage caused by overuse of chemical fertilisers. Biochar, a recalcitrant carbon-rich product of pyrolysis which may be added to soil as a fertilizer or as a soil improver, alters soil physico-chemical properties usually by acting as a liming agent, by increasing water holding capacity or by modifying cation exchange capacity. The effects of biochar on the soil microbial community are not fully understood. Therefore, the main aim of this investigation was to evaluate the effects of biochar on the Rhizobium-legume relationship and determine whether biochar could increase legume growth. To achieve this aim, a series of growth experiments were carried out under controlled conditions in which broad bean (Vicia faba) was grown with Rhizobium leguminosarum and the symbiosis tested against three concentrations of biochar applied as a soil amendment and with two different char particle sizes. Beans responded well to Rhizobium under char-free conditions but the effects of biochar on the symbiosis were variable and depended on char particle size, concentration and Rhizobium strain (commercial or indigenous). Powdered char inhibited plant growth when in the presence of the commercial rhizobia, but not with indigenous strains. This is an important finding since commercial inocula are commonly used in agronomic situations. Plant available soil nutrients were modified by biochar and surprisingly by an interaction between char concentration and the two rhizobia strains. When beans were co-cropped with wheat, beans performed better when grown with powdered char than without. This is in contrast to the response of bean plants to powdered char in the absence of any competition. Since wheat was generally the superior competitor, powdered char amendment enabled the bean to take advantage of the N-limiting environment that powdered char created and perform better than in the soils that advantaged the wheat. The investigation highlighted the complexity of the system, but identified the importance of char particle size and Rhizobium strain selection.

This study investigated the simulated impact and vibration tests on bruise damage and quality of the British strawberries from winter and summer cultivations. The actual transport of food products was also monitored for the vibration and temperature levels in the city and highways. The winter cultivation produced a superior overall quality of 'Elsanta' and 'Sonata' strawberries compared to the summer cultivation. 'Sonata' fruits were more sensitive to vibration damage in the summer cultivation. The packed strawberry punnet of 250 g was tested in impact and vibration tests. The maximum drop height at 750 mm gave a significantly larger wet bruise level of around 40% than other drop heights (p.0.05). The simulated vibration investigated the three frequencies and three exposure times plus control. The vibrated fruits from the most severe of 5 Hz (1.1 g) for 150 sec had significantly higher wet bruises (50-60%) than for other treatments (p.0.05). The bruise damages increased for both simulated tests after storage at 10°C, 70±5% RH for 3 days. The EC value gave a significantly stronger correlation with wet bruise and severity score as compared to puncture, compression and respiration rate measurements (p.0.01). The EC method is suggested for use as a rapid indicator and a predictor for the bruise assessment of strawberries. The vibration and air temperature levels in the refrigerated truck and semi-trailer were monitored. The overall peak frequency of power density was often found at 10-14 Hz. The vertical vibration was the dominant direction during the road transport. The rear-top position gave a stronger root mean square acceleration value. A gradual increase of vibration level occurred after the first drop in city distribute as well as for a smaller load. The range of temperature during food transport was around 2 to 8oC with a set point at 3°C.

Master of Science / Department of Agricultural Economics / Ted Schroeder / Demand indices are used by many industries as a measurement tool to track changes and make yearly comparisons. Many different sources use demand indices to track the demand for beef. Indexes are an important tool to help better understand why demand shifts the way that it does and help strategically plan for the future of the industry. There are a wide variety of beef demand indices out in academia and many are constructed in different ways. This study advances the literature by testing which factors of index construction effect the results the greatest. This study tested four separate factors in the construction of demand indices. These iterations are as follows, changes in retail price data, changes in elasticities chosen, changes in export data, and changes in construction in terms of quantities instead of prices. Changes in retail price data do not appear to be statistically different. All estimates in this study where elasticities were changed appear to be different statistically, however the level of concern with this finding may be minimal due to the small increments of change in magnitudes of difference between indices. Results from omitting export data does appear to result in statistically different indices, but again the level of concern with the difference may be small. Finally, index construction in terms of prices versus construction in terms of quantities does not appear to have statistically different results, as the indices in this comparison move similarly. For all practical purposes in industry, it does not appear to matter which index is chosen for comparisons, as long as one remains consistent with which index is chosen for comparisons.

Two methods of vegetative propagation, stem cuttings under mist and air layering, were examined for the 'Desert Museum' hybrid palo verde and species of Cercidium, Parkinsonia, and Prosopis. Basal cuttings of 'Desert Museum' gave higher rates of rooting than apical cuttings and showed better rooting in April than September. Two-node cuttings produced more rooted cuttings for an equal stem length than three- or four-node cuttings. Cuttings of six other species and hybrids of Cercidium and Parkinsonia, as well as six species and hybrids of Prosopis, were also successfully rooted. Indolebutyric acid (IBA) in the range of 2,500 to 5,000 ppm generally improved rooting compared with no IBA treatment. Bottom heat of 30 to 35°C was required for high rooting rates for all species. Air layers of Prosopis chilensis averaged 94% rooting using stem diameters of 8 to 10 mm. IBA at 5,000 ppm improved rooting by 70% over 0 ppm. Air layers of Cercidium, Parkinsonia, and other species of Prosopis were also rooted.

Master of Science / Department of Agricultural Economics / Andrew P. Barkley / Andrew P. Barkley / This research will identify and quantify the determinants of international wheat trade from 1999-2008. This study will focus on the following objectives: (1) Review literature on international wheat trade to develop a suitable conceptual model (2) Quantify the impact of economic variables including price, income, exchange rates, transportation costs, and trade policies; and (3) Extend previous work by further consideration of trade policies and international relationships. Regression results indicate that economic factors continue to play a major role in wheat trade. Domestic price had the largest level of statistical significance of non-trade agreement factors in this analysis. The regression results highlight that national income, distance between nations, exchange rate, inflation and respective populations are also important in determining the flow of wheat. Openness to trade and agriculture production variables were statistically significant, demonstrating the commodity nature of wheat trade. Sharing a common border and language are also positive factors in wheat trade. Colonial heritage does have some small impacts, negative for direct colonies and positive for nations sharing a common colonizer. This analysis extends previous international wheat trade research through the inclusion of multilateral relationships and bilateral trade agreements. This study showed that not being a member of the WTO is a positive factor in the trade of wheat. The review of trade agreements added depth to this study by examining both trade creation and trade diversion for each agreement specifically for their effects on wheat trade. The estimated models show that nations which develop agreements with contrasting qualities from themselves are likely to see higher gains from free trade agreements. However, when nations engage in agreements with nations in a similar location or income structure, trade diversion iv occurs. The analysis also shows that trade agreements can overcome factors that may have a negative impact on the trade of wheat such as distance or colonial relationships. By understanding the determinants of wheat trade, players in the wheat market can create a more transparent and fluid trading system.

The Agricultural Development Fund (ADF) is the Government agency responsible for financing farmers in the Saudi Arabian agricultural sector. The ADF provides short-term loans and medium-term loans and funds specialised projects, as well as providing subsidies for some types of loans. From its establishment in 1962 until 2012, the ADF has lent more than £7.7 billion and the total number of loans exceeds 439,000. However, in spite of the facilities provided by the ADF, its annual reports show that the outstanding debt increased from £579 million in 1990 to £840 million in 2012; moreover, the reports reveal that some project areas have been receiving more funding than others. This thesis aims to assess the efficiency of the collection of loan repayments by the ADF. This aim will be achieved through four objectives: 1) analyse the current status of the regional distribution of agricultural loans to determine the optimal distribution of loans among regions to achieve development objectives, 2) examine the determinants of the efficiency of loan collection to identify and quantify factors that affect loan repayment, 3) explain the variation in collection rates among the ADF's branches and 4) provide recommendations to improve the probability of repayment and achieve the optimal distribution of loans. Variation in the current distribution of agricultural loans among regions has been observed. Using Multiple-Attribute Analysis, this variation has been identified as sub-optimal with respect to achieving development objectives. The highest priority regions for agricultural loans are the Northern, Jazan and Baha regions. Logistic modelling approaches have been used to determine factors affecting the repayment of short-term loans, medium-term loans and specialised projects; the empirical results of the overall model for short-term loans show that the age of the borrower and four regions have a positive significant effect on loan repayments, while the grace period, the loan value, the financial guarantee and three regions each have a significant negative effect. The results of the analysis of medium-term loans reveal that five variables have a significant effect on loan repayments: age, the grace period and loan value have a negative effect. Financial guarantee and three regions have a positive effect. The results for the specialised projects showed that the Hail region, feed and wheat project have a positive effect, while the Eastern region and greenhouses, livestock and vegetables projects have a negative effect on loan repayments, whereas the age of the borrower, the grace period, financial guarantee and loan value have no significant effect.