Diss. Uppsala : Sveriges lantbruksuniv., 2001.

Competition with weeds decreases crop yields globally. Some traits are known to confer a competitive advantage to spring bread wheat (Triticum aestivum L.), but complex relationships between the competitive traits makes breeding for competitive ability difficult. Prairie organic producers use spring wheat cultivars which have been bred for conventional management systems or heritage cultivars released before the widespread use of synthetic fertilizers and pesticides. Breeding spring wheat specifically for organic production has been suggested. The International Triticeae Mapping Initiative (ITMI) population was used to study the genetics of traits associated with competitive ability. Grain yield without weed competition and under experimentally sown cultivated oat competition exhibited similar heritability. Similar heritability estimates between competition treatments suggest that selection in a weed free environment can lead to improvements in a weedy environment, but some high yielding lines under competition would be eliminated during selection. Quantitative trait loci (QTL) analysis of the population found QTL associated with vigour, days to heading, anthesis, and maturity, and cultivated oat grain yield suppression on chromosome 5A. The genetic correlations support the idea that early maturity provides a competitive advantage in northern grain growing regions. To investigate the feasibility of organic wheat breeding we used a random population of 79 F6-derived recombinant inbred sister lines from a cross between the Canadian hard red spring wheat cultivar AC Barrie and the CIMMYT derived cultivar Attila. The population, including the parents, was grown on conventionally and organically managed land in 12 environments over three years. Six environments had detailed agronomic data and heritability estimates differed between systems for five of the 14 traits recorded. Direct selection in each management system (10% selection intensity) resulted in 50% or fewer lines selected in common for four of the traits. Over all 12 environments direct selection within management system resulted in three lines retained specific to each system. The results of the management studies suggest that selection differences occur across multi-location tests, and selection for grain yield in organic systems should be conducted within organic systems. However, data garnered from conventional yield trials does have some relevance towards breeding for organic environments. / Plant Science

No description available.

The purpose of this study was to determine Texas AgriLife Extension agents' perceptions of organic agriculture (OA) and implications for training. Primary variables of interest included level of interest in OA in their respective counties, previous training received, interest in future training, perception of OA and Texas AgriLife Extension's involvement in OA. A random sample of agents was selected (n = 151) and a response rate of 81.5 percent was achieved. A majority of agents indicated interest in OA in their respective counties had increased over the past five years (n = 60), but noted demand was still low (n = 39) to moderate (n = 42). Agents from urban or suburban counties reported higher levels of interests in OA than did agents from rural counties. Agents were most interested in training on organic soil fertility, insect, weed, and disease management and least interested in training on organic certification and transitioning to OA. Agents indicated traditional information resources would be the most useful delivery methods for communicating information about organic farming, which included print publications, a website with organic information and extension workshops. Agents' perceptions of OA and their perceptions of Texas AgriLife Extension's involvement in OA were measured using attitudinal statements using a five point summated scale with reliability estimates r = 0.76 and 0.76 respectively. It was found that agents neither agreed nor disagreed with statements affirming the viability of OA (M = 2.80) and statements advocating Texas AgriLife Extension's involvement in OA (M = 3.38). A stepwise multiple regression was run on the primary variables of interest to determine which variables predicted agents' interest in training. Perceptions of Texas AgriLife Extension's involvement, perceptions of OA, and current level of interest in their county accounted for over 50 percent of the variability. This research concluded that due to agents' general ambivalent attitude toward OA, Texas AgriLife Extension administration will need to advocate more training and programming in OA if they wish to increase their role in OA. For there to be any significant change in the advancement of OA, though, it will require a paradigm shift in the land grant university system (LGUS).

Made available in DSpace on 2014-06-11T19:28:27Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-09-06Bitstream added on 2014-06-13T20:37:19Z : No. of bitstreams: 1 silva_fc_me_prud.pdf: 2722183 bytes, checksum: 2460d224acf0d67e0e871de7872eb8d7 (MD5) / A chamada modernização da agricultura representou um período de intensificação do processo de degradação ambiental e modificação profunda nas relações de trabalho.Um dos movimentos de resistência a esse novo padrão de produção verticalizada é a agricultura orgânica. No Estado de Santa Catarina, essas experiências têm se desenvolvido amplamente, assumindo características próprias e gerando uma diversidade de relações sociais que tem deflagrado novos movimentos territoriais. No caso chapecoense, a agricultura orgânica desenvolve-se amparada por agricultores, ONG s e Cooperativas, criando uma rede territorial que assume ritmos e tempos diferentes, mas que tem construído um novo território nesse município. Novo justamente porque pensa e organiza os elementos do espaço geográfico seguindo um padrão próprio, construído coletivamente e produto da diversidade cultural, política, econômica e ambiental local. Novas redes e fluxos foram ativados inserindo esses atores sociais de uma forma singular no contexto local. Buscando compreender essas relações lançou-se mão de revisão bibliográfica, revisão de sítios especializados, entrevistas, trabalhos de campo, aplicações de questionários, entre outros, que possibilitaram a coleta de dados para posterior compilação e apresentação em forma de mapas temáticos, tabelas, gráficos e conclusões teóricas a respeito da agricultura orgânica enquanto movimento territorial no município de Chapecó, Oeste catarinense. / The so-called modernization of agriculture exemplified a period of intensification of the process of environmental degradation and profound changes in work relations. One of the resistance movements to this new standard of verticalized production is organic agriculture. In the state of Santa Catarina, these experiments have developed widely taking on their own characteristics producing a variety of social relations that have evolved into new territorial movements. In the case of Chapecó, organic agriculture has developed supported by agriculturalists, NGOs and cooperatives, creating a territorial network that has taken on different times and rhythms, but which has built a new territory in this municipality. It is new exactly because it thinks and organizes the elements of geographic space following its own standard, building collectively, and is a product of cultural, political, economical and local environmental diversity. New networks and currents were activated, inserting these social actors in a singular manner in the local context. Seeking to comprehend these relations, bibliographic revision, specialized farm revisions, interviews, field work, use of questionnaires, among others were employed, which allowed for information gathering for later compilation and presentation in the form of thematic maps, tables, graphics and theoretical conclusions regarding organic agriculture as a territorial movement in the municipality of Chapecó in the western region of Santa Catarina.

No description available.

In recent decades the knowledge of nitrous oxide (N2O) emissions after the application of nitrogen (N) fertilizers in agriculture soil has improved. However the understanding of emissions of N2O from Canadian organic agricultural systems has not been developed. The Glenlea Long Term Crop Rotation is the longest running organic conventional comparison study in western Canada and was used here to compare N2O emissions between the systems. In organic cropping systems forage legumes such as alfalfa are incorporated into the soil as an N source. The amount of N2O that is emitted after the incorporation and during the subsequent crop is not well known. The wheat and legume phases (alfalfa (Medicago sativa) in organic system and soybean (Glycine max L.) in the conventional) of the rotation were monitored for N2O. In 2014, 2015, and spring 2016 (data still being analysed) emissions of N2O were monitored using the vented static chambers method as well, soil conditions (temperature, moisture, inorganic N and extractable carbon) and yields were measured. Typical N2O emissions from spring applied urea were observed after application in the conventional system however no emission episode was seen after the fall alfalfa plough down or during spring thaw in the organic system. Greater NO3- accumulation was observed in the organic treatments however low emissions were observed. The organic system resulted in lower yields for both years, but still resulted in lower emissions per amount of grain produced (yield-scaled emissions) than the conventional system. This study adds to the knowledge that N2O emissions from organic systems do differ from conventional however yields need to be improve to fully exploit the benefits. / February 2017

Sowohl der europäische, als auch der tschechische Markt für Bioprodukte wächst, und mit ihm auch die Anzahl der Kennzeichen, Logos und Versprechen, die im Verbraucher den Eindruck von ökologischer Verträglichkeit oder Nachhaltigkeit erwecken sollen. Diese Arbeit hinterfragt den rechtlichen Rahmen der Bioprodukte und überprüft dementsprechend, welche Regelungen auf dem Gebiet schon bestehen, auf welche Gebiete diese sich beziehen und, ob diese Regelungen in der Praxis wirklich genügen. Gerade, weil auch der tschechische Verbraucher immer mehr Kaufentscheidungen von Kriterien der Nachhaltigkeit und seinem Umweltbewusstsein abhängig macht, ist das Thema rechtswissenschaftlich sehr relevant. Diese Arbeit analysiert die europäische Regelung, hauptsächlich die "Ökologische Landwirtschaftsverordnung", aber auch die nationale tschechische Regelung, das "Ökologische Landwirtschaftsgesetz", da die Gestaltung des Kontrollsystems der Produkte und andere organisatorische Regelungen den Mitgliedstaaten überlassen werden. Näher befasst sich die Arbeit hauptsächlich mit Problemen der ökologischen Landwirtschaft in der Tschechischen Republik und deren rechtlichen Hintergrund. Um zu überprüfen, wie weit der allgemeine rechtliche Rahmen der Bioprodukte den Erwartungen des immer umweltbewusster werdenden Verbrauchers...

No description available.

Grazing and no-till management in organic systems have been recently proposed tools to improve nutrient cycling and sustainability. From 2008 to 2012 a series of field experiments were established to identify green manure species and green manure management options to maximize N benefit to following cash crops and explore the opportunities to reduce tillage during the green manure phase of an organic rotation. A total of four green manure systems (double-cropped green manures, relay-cropped green manures, full season green manures, and catch crops after grazed full season green manures), three green manure management options (soil incorporation, grazing and no-till), and 10 green manure species, as well as, three green manure mixtures were tested. Double-cropped pea (Pisum sativum cv. 40-10) and relay-cropped red clover (Trifolium pratense) produced around 900 kg ha-1 and 2000 kg ha-1 of biomass respectively. The greatest biomass producing full season green manures were hairy vetch (Vicia villosa L.), pea/oat (Avena sativa cv. Leggett/Pisum sativum cv. 40-10) and sweet clover (Mellilotus officinalis cv. Norgold). Pea/oat and hairy vetch were the most weed competitive species and on average contained less than 15% weed biomass. Among all the systems and managements tested, nitrogen availability was greatest when full season green manures were grazed. On average grazing increased soil NO3-N by 25% compared to soil incorporation using tillage. Among grazed species, pea/oat mix and hairy vetch green manures resulted in the greatest amount of soil available NO3-N. Catch crops after grazing green manures, regardless of the species, significantly reduced N leaching risk compared to no catch crop treatment, but also reduced wheat productivity the following year. Catch crop biomass productivity and N uptake, soil NO3-N, and wheat productivity were similar in direct seeded and conventionally seeded plots. Grazing may be an effective tool in reducing tillage in organic agriculture because of its ability to accelerate the N mineralization from catch crop biomass. This study was the first study to use grazing as a management tool for green manures in organic systems. Results provide strong evidence that green manures, especially when grazed, can be effective nitrogen suppliers in organic grain based rotations.