La introducció de noves tecnologies en l'àmbit agroalimentari ha revolucionat la eficiència pel que fa al sector productiu, si bé també ha tingut efectes rellevants pel que fa a la demanda, que cal analitzar amb profunditat. Aquest és el cas dels productes modificats genèticament, que solen ser productes de consum habitual, per la qual cosa han creat una important polèmica.Hi ha diferents agents del mercat que participen en aquest debat, com és el cas dels productors, els quals en poden obtenir benefici pel que fa a millores en eficiència i reducció de costos. Tanmateix, és essencial tenir en compte l'opinió dels consumidors alhora d'analitzar els límits comercials de les noves tecnologies.Per a conèixer l'opinió dels consumidors cal entendre el seu procés d'elecció i de valoració dels productes agroalimentaris, com també el seu comportament a l'hora de prendre decisions en el mercat alimentari.Aquesta tesis comença amb una extensa revisió bibliogràfica en relació a les actituds dels consumidors vers els productes modificats genèticament.Seguidament s'analitza la intenció de compra dels consumidors utilitzant experiments d'elecció. L'objectiu principal d'aquesta tesi s'ha assolit amb els subsegüents capítols on s'han analitzat els diferents elements cognitius que porten a l'individu a la intenció final de compra. La metodologia emprada ha estat principalment equacions estructurals i experiments d'elecció. S'han emprat diferents bases de dades per a poder contrastar totes les hipòtesis plantejades en l'estudi.La principal contribució d'aquesta tesi ha estat determinar quins son els elements que cal considerar per entendre el procés de decisió del consumidors vers els aliments modificats genèticament, com també determinar que existeix un clar escepticisme en la societat pel que fa a aquests productes. Les conclusions d'aquesta tesi posen en manifest la necessitat de una millor estratègia de comunicació que permeti als consumidors una percepció de millor i major qualitat d'informació en relació a aquests productes. / The introduction of new technologies in food production not only has revolutioned its productive efficiency but has exerted important demand side effects that cannot be dismissed and require careful analysis. This is especially the case of genetically modified (GM) food, typical daily consumed products (e.g. GM milk, tomato, maize, etc) given its considerable interest and worldwide public controversy. Several stakeholders are place, on the one hand, farmers and manufactures perceive potential benefits from efficiency improvements as well as costs, mainly resulting from the need to reimburse intellectual property rights for new foods. From a demand side, GM food brings new products in the food chain and ultimately fulfils to an extent a latent consumer's preference for diversity. Hence, in order to determine the limits of technology dissemination and transfer it becomes a key issue to examine and disentangle which demand side factors stand behind technology acceptance. This calls for a better understanding of consumer choice, its valuation and the behavioural decision making process.The valuation of a new technology good implies the provision of information from several sources - public and private, formal and informal, etc - while conditioning on the credibility and trustworthiness of each relevant information source. Given the information available, a further issue concerns attitude expression and formation, which ultimately leads to the final question regarding product valuation and consumer preference. Interestingly, attitude formation for the case of new food generations is found to be explained by a combination of risk and benefit perceptions, based on different elements such as a general attitude towards science, knowledge, trust, education and values, among others.This thesis begins with an extensive review of the literature on attitudes towards GM agro-food products- chapter 2- by means of a literature review. Next it conducts a study on consumers' final intentions towards agro - food products, entailing the application of choice experiments - chapter 3. moreover, the main core of this dissertation is aiming at examining what gives rise to the final choice (chapters 4 to 6). The methodologically employed relies on structural equation modelling, although in each chapter different databases have been used. The relative strengths of each database allow us taking into account the information required to test specific hypotheses. Finally, some conclusions are drawn in chapter 7 which summarises the main findings of each chapter and put them in context of the main discussion questions examined in this thesis.The main contribution of this thesis has been to point out a set of features that condition choice, intentions and revealed purchase intentions regarding GM food. Our wok is innovative in that: 1) it contains an innovative literature review; 2) develops choice modelling of scenarios that includes, apart from methodological features, the choice between GM processed and organic food; and 3) unlike most of behavioural analysis it exploits using structural equation modelling, several theoretical structures that explain decision making and, particularly, the role of broader attitudes towards science and technology in influencing purchase intentions alongside the effect of both risks attitudes and risk perceptions in determining consumer acceptance.The sequence and findings of the thesis can be summarized as follows: drawing from an exhaustive review of published finding regarding public intentions towards GM food we conclude that there is consumer's scepticism explaining a negative valuation towards GM food. However, the most important outcome has been to find that final purchasing intention is the result of a complex decision process which only has been partially explained in the literature. Therefore, upon the definition of a general theoretical model this thesis has tried to explain in the different chapters some specific issues of such model as well as to validate it in a croos - country exercise in the last chapter. Results from this study rises a key policy implication: the need of a well defined communication stralegy to provide information in such a way that allows individuals to feel adequately informed.

El surgimiento de una nueva forma de hacer agricultura respetando al medio ambiente y vinculada con la producción de alimentos sanos y orientados al mercado de exportación, ha venido ganando importancia en la agricultura mundial durante las ultimas tres décadas. Esta nueva forma de agricultura es conocida como Agricultura Ecológica.En la presente Tesis Doctoral se hace un análisis de la agricultura ecológica y de los productos que esta genera en Europa y de manera particular en España, desde los antecedentes hasta la situación actual, pasando por los beneficios, la legislación, el consumo, la calidad, la certificación, las estrategias de identificación (etiquetas), entre otras, como punto de partida para la implantación de este sector ecológico al agro mexicano. Se realiza un diagnostico desde el punto de vista ecológico y muestra la oportunidad que se presenta para un país como México, de incorporar este tipo de agricultura, tanto para la mejora del medio ambiente, como para un mejor desarrollo socioeconómico, sin perder de vista las raíces culturales. México, es un país con vocación agrícola, con climas favorables y territorios disponibles para este tipo de explotaciones, y esta Tesis demuestra su viabilidad, a través del rescate de tecnologías tradicionales y la incorporación de métodos de certificación y sistemas de comercialización, contribuyendo para la mejora de la calidad de vida de la sociedad actual (indígenas, campesinos, productores, comerciantes, consumidores, etc.), mostrando cambios en la demanda de los alimentos, criterios para la salud y nuevas exigencias ambientales.Se hace un análisis del marco jurídico que marcan las leyes mexicanas, en cuanto a aspectos de regulación ambiental, equilibrio ecológico y contaminación del suelo, se estudian la importancia social y económica, así como la normativa y los procesos de certificación, etiquetado y comercialización.Como parte prioritaria se analizan casos prácticos de organizaciones que ya trabajan la agricultura ecológica en México, y que han sido reconocidas a nivel Nacional como Internacional, como el caso de la Unión de Comunidades Indígenas de la Región del Istmo (UCIRI), principales productores de café ecológico en México, de los Productores Orgánicos del Cabo de Baja California Sur y de la Red de Alternativas Sustentables Agropecuarias (RASA), con sede en Guadalajara, Jalisco., ejemplos a seguir para la implementación de la agricultura respetuosa del medio ambiente a nuevas comunidades agrícolas del país, fortaleciendo su identidad cultural y la conservación de los recursos naturales.El producto principal de esta Tesis Doctoral, es la generación de una propuesta de un sistema de garantías de calidad en los procesos productivos y de comunicación, para el impulso de la agroecología en México, propuesta que se orienta hacia el aprovechamiento del potencial de la agroecología como eje impulsor del desarrollo local, manteniendo a la población activa en el medio rural."Queda mucho por construir pero, tal como se ha visualizado a lo largo de la investigación, las posibilidades de desarrollo local apuntan optimistas siempre y cuando se conjunten las voluntades y los esfuerzos hacia un bien comun..."Mario A. Orozco / The emergence of a new form of making agriculture giving respect to the environment linked to the production of healthy foods oriented to export markets has gained importance in world agriculture in the last three decades. This new form of agriculture is known as Ecological Agriculture.This Philosophy Doctor thesis analyses ecological agriculture and the products that it generates in Europe, Spain in particular, from its roots until the present situation, reviewing its benefits, legislation, consumption, quality, certification, the identification strategies (labels), among others, as the starting point for the implementation of this ecological sector in Mexican agriculture.A diagnosis is being made from the ecological point of view showing the opportunity of introducing this type of agriculture to a country like Mexico, for environmental improvement as well as for a better socioeconomic development without loosing cultural roots.Mexico is a country with agricultural inclination, with advantageous climate and available territories for this type of exploitaion, and this thesis demonstrates its viability through the recovery of traditional technologies and the introduction of certification methods and marketing systems, contributing for the improvement of society's quality of life (indigenous groups, farmers, producers, merchants, consumers, etc.), showing changes in food demand, health criterion and new environmental demands.An analysis of the legal frame determined by Mexican laws is being made, in terms of environmental regulation, ecologic equilibrium and soil pollution; economic and social importances are being studied as well as standardization and certification processes, labeling and marketing.As a priority, practical cases of nationaly and internationaly recognized organizations that work with ecological agriculture in Mexico are being analysed, such as Unión de Comunidades Indígenas de la Región del Istmo, UCIRI (Indigenous Communities Union of the Isthmus Region), leading producers of ecological coffee in Mexico, Productores Orgánicos del Cabo de Baja California Sur (Cape Organic Producers of South Baja California) and Agricultural Sustainable Alternative Network, headquartered in Guadalajara, all of these as examples to be followed for the implementation of environmentally respectful agriculture in new rural communities in the country, reinforcing their cultural identity and the conservation of natural resources.The main product of this Ph. D. thesis is the generation of a proposal of a quality guarantees system in the productive processes and communication for the impulse of agroecology in Mexico, oriented to take advantage of the potential of agroecology as an impulse force of local development, keeping the rural population active."There is a lot to be built but, just as it has been visualized through the research, the possibilities of development seem optimistic only if efforts and wills are joined to a common welfare."Mario A. Orozco