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Master of Science / Agronomy / Robert Aiken / Xiaomao Lin / Productivity of water-limited cropping systems can be reduced by untimely distribution of water as well as cold and heat stress. The research objective was to develop relationships among weather parameters, water use, and grain productivity to produce production functions to forecast grain yields of grain sorghum and winter wheat in water-limited cropping systems. Algorithms, defined by the Kansas Water Budget (KSWB) model, solve the soil water budget with a daily time step and were implemented using the Matlab computer language. The relationship of grain yield to crop water use, reported in several crop sequence studies conducted in Bushland, TX; Colby, KS and Tribune, KS were compared against KSWB model results using contemporary weather data. The predictive accuracy of the KSWB model was also evaluated in relation to experimental results. Field studies showed that winter wheat had stable grain yields over a wide range of crop water use, while sorghum had a wider range of yields over a smaller distribution of crop water use. The relationship of winter wheat yield to crop water use, simulated by KSWB, was comparable to relationships developed for four of five experimental results, except for one study conducted in Bushland that indicated less crop water productivity. In contrast, for grain sorghum, experimental yield response to an increment of water use was less than that calculated by KSWB for three of five cases; for one study at Colby and Tribune, simulated and experimental yield response to water use were similar. Simulated yield thresholds were consistent with observed yield thresholds for both wheat and sorghum in all but one case, that of wheat in the Bushland study previously mentioned. Factors in addition to crop water use, such as weeds, pests, or disease, may have contributed to these differences. The KSWB model provides a useful analytic framework for distinguishing water supply constraints to grain productivity.

Part I: Systematic Literature Review. Dysregulation of the motivational and incentive functions that underlie goal setting and goal pursuit is thought to be a key factor implicated in the aetiology of Major Depressive Disorder. Although research over the past two decades has shown that motivational and cognitive factors can play an important role in increasing negative affect and making individuals vulnerable to depression, much of this work has involved dysphoric and non-depressed samples and much less is known about their role in the maintenance of and recovery from clinical depression. The objective of the present study was therefore to identify and synthesize the evidence from studies that examined goals, goal pursuit and goal orientation in clinically depressed individuals. Only 9 studies meeting the inclusion criteria could be identified through systematic literature searches and were heterogeneous in design and quality. The results therefore do not allow strong conclusions to be drawn and need to be interpreted with caution. Bearing this caveat in mind, the findings did not support the idea that depressed individuals set fewer, less valued or more avoidant personal goals than non-depressed individual and suggested that problems were more likely to lie in the motivational and cognitive processes governing goal engagement and goal pursuit. Factors identified by the present studies likely to play a significant role in disrupting motivational processes and promoting maladaptive strategies of goal pursuit were perceived goal attainability, perceived lack of control, personal resources and skills required, type of goal focus, lack of goal specificity and goal engagement and disengagement processes. The results of two randomised clinical trials further suggested that therapies focusing on goal dysregulation in patients identified to lack adaptive strategies for goal pursuit and goal reengagement may be more effective than standard models. These findings identified promising areas for future research and highlight the importance of understanding individual profiles and subtypes of depression in order to target key areas of dysregulation and tailor treatment accordingly and in collaboration with the patient. The review highlighted the paucity of good quality studies involving samples of clinically depressed individuals and the need for more translational work focusing on clinically significant outcomes and developing reliable measures to assess day-to-day goal engagement and pursuit in depressed individuals. Abstract - Part II: Empirical paper. Goal orientation theory suggests that adopting a self-worth goal orientation (seeking self-validation and avoiding proof of worthlessness) may make individuals more vulnerable to depression, whereas pursuing learning goals (seeking personal growth and improving one's abilities) might represent a protective factor. This study examined whether adopting different goal orientations following negative performance feedback and unfavourable social comparison affected mood and performance on a subsequent performance task. Trait goal orientation was assessed in a sample of 86 U.K. university students who were allocated to three experimental groups receiving self-worth goal, learning goal and no instructions after receiving negative feedback on the first performance task. The findings provided some support for the original predictions of goal orientation theory (Dykman, 1998). Validation-seeking was associated with greater anticipatory anxiety following a negative event as well as reduced confidence when faced with a performance challenge. However, the results provided no substantial evidence to suggest that adopting a 'state' learning goal orientation vs. self-worth goal orientation mitigates the experience of negative affect or helplessness responses. Potential implications of the findings regarding the utility of the goal orientation construct as a predictor of depression vulnerability are discussed in the light of methodological limitations of the present study.

Depression accounts for the largest proportion of the burden associated with all mental health disorders and is predicted to be the second leading cause of the global burden of disease by 2020. Despite the apparent efficacy of prevention programmes, international rates of help-seeking for depression remain poor. Cognitive theories of help-seeking and empirical studies suggest that help-seeking for health conditions is largely determined by beliefs about the condition (e.g., likelihood and severity of the condition) as well as beliefs about help-seeking itself (e.g., how easy and beneficial it would be to get help). An understanding of the role of health beliefs in help-seeking for depression will hopefully close the gap between the number of people eligible for depression treatment and the number of people actually receiving it. A systematic review of literature was conducted to identify studies that examined the relationship between health beliefs and help-seeking for depression using the highest quality study design, i.e., experimental trial or prospective cohort. Six electronic databases were searched and a manual search of the reference lists of the included studies was conducted. Ten studies with a total of 7,878 participants were included in the review. In line with theories of health behaviour, what participants believed about depression and about preventive health action was related to whether they sought help; however, the association between beliefs and help-seeking varied across studies. Methodological issues and overall low study quality point to the need for high quality studies with clearly defined constructs and reliable and valid variable measurements. The findings of this review suggest that beliefs about depression are important targets for interventions aimed at improving rates of help-seeking for the illness.

Research is increasingly attempting to understand the developmental nature of depressive symptomology and its links with executive functioning (EF), repetitive negative thinking (RNT) and stress (e.g., Snyder & Hankin, 2016). Prospective studies are needed to explore the potential mechanisms underlying these associations. This study investigated whether EFs can predict changes in RNT, stress and depressive symptoms during a period of stress. One hundred and two undergraduates completed questionnaires measuring life events, trait and state RNT, depressive and anxious symptoms as well as behavioural EF tasks of cognitive switching and inhibitory control at baseline (Time 1). Follow-up questionnaires of RNT, stress, depression and anxiety were gathered approximately two months later (Time 2), during students’ formal examinations, a period of naturally elevated stress. Findings indicated no association between EF and RNT, depression or anxiety but found that the interaction between high levels of trait RNT and low levels of EF (switching) at baseline was a significant predictor of change in state RNT under stress. Findings are discussed in light of current research attempting to unpick associations between EF, RNT and depression in young adults.

Background Adult colouring books have become increasingly popular in recent years, with suggestions that they can reduce stress and increase calmness, but there is currently a limited evidence base in this area. This study explored whether colouring-in is more effective than a neutral distraction activity and rumination in improving affect and state rumination after experiencing a laboratory stressor that involved solving difficult anagrams. Method The study was a mixed (3 x 3) experimental design, with condition as the between-subjects factor (distraction, colouring-in, rumination) and time as the repeated measures factor (baseline, post-stressor, post-manipulation). An undergraduate student sample (N = 90) was randomly assigned to one of three experimental conditions. Participants completed the State Rumination Questionnaire (SRQ) and Positive and Negative Affect Schedule (PANAS) to measure the impact of the stressor and the effects of each experimental condition. Results After experiencing the stressor, participants showed a significant increase in negative affect (p < . 001) and state rumination (p < . 001), and a significant reduction in positive affect (p < . 001). Participants in the colouring-in and distraction condition experienced a significantly greater improvement in negative affect than participants in the rumination condition (p = .001). Furthermore, the difference between the effects of the rumination versus the distraction conditions on negative affect was significantly more pronounced for people reporting higher levels of depressive symptoms (p < . 001). No significant difference was found between colouring-in and distraction conditions on state rumination (p = .52), positive affect (p = .92) or negative affect (p = .23). There was no significant difference between conditions change in state rumination (p = .81). Conclusion Findings from this study suggest colouring-in is as good at alleviating negative affect as a traditional distraction intervention. Results replicate previous findings that distraction activities are associated with mood improvement compared to rumination. However, distraction activities used in this study failed to change state rumination across conditions. Further research is required to understand the mechanisms underlying colouring-in which are associated with effects on mood.

Call number: LD2668 .T4 1964 M687 / Master of Science

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