Browsing by Subject "Organic"

Now showing 1 - 4 of 4
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    A study of integrated weed control strategies for establishing soybean (Glycine max L. MERR.) in the German production system
    (2017) Weber, Jonas Felix; Gerhards, Roland
    Soybean (Glycine max L. MERR.) has expanded to become one of the most traded agriculture products worldwide in recent decades. Europe is one of the primary importing regions; however, the dependence on soybean imports has been critically assessed by the public. To reduce the dependency on soybean imports, increased local soybean production should be favoured. In addition to environmental conditions, weeds are a major limiting factor for soybean yield under German climate conditions. Weeds can be successfully controlled with herbicides, although crop injury frequently occurs after application. Sensor-based screening would be helpful for a rapid evaluation of cultivar tolerance to herbicide application. Alternatively, mechanical weed control strategies can be applied. Since soybean production is currently introduced to the regional crop production, weed control efficiency of conventional mechanical tools (e.g., hoeing and harrowing) have to be evaluated. By using automatic guiding systems intra-row elements could be utilised to increase the weed control efficiency of mechanical hoeing. Other than that, agronomical practices such as the tillage system or cover crops influences the occurrence of weeds. The most common practise worldwide for soybean cultivation is the no-tillage system, which has not yet been investigated under local conditions. Therefore, different weed control strategies in soybean production were investigated according to the following major objectives of this thesis: - Detection of crop injury by herbicides using a chlorophyll fluorescence imaging sensor for different soybean cultivars. - Evaluation of the conventional mechanical strategies of hoeing and harrowing in soybean. - Examination of the weed control efficiency in inter- and intra-row areas using RTK-GNSS precision steering and an optical camera guiding system for mechanical weed control in soybean. - Evaluation of the efficiency of ‘tillage’, ‘reduced tillage’ and ‘no- tillage’ cultivation systems and the influence of cover crops on weed suppression in local soybean production. The Imaging-PAM-sensor based on chlorophyll fluorescence imaging was utilised to investigate the response of different soybean cultivars to the application of herbicides. The measurements indicated significant differences with respect to injury to the cultivars after herbicide application. Herbicides containing the active ingredient ‘metribuzin’ resulted in significant differences in the level of crop injury depending on the cultivar. The active ingredients ‘dimethenamid’ and ‘clomazone’ resulted in less injury, independent of the cultivar. The PAM-sensor was able to detect stress symptoms 3 to 7 days before visual symptoms appeared. An investigation of hoeing and harrowing, which are conventional mechanical techniques for weed control, showed 78% and 72% weed control efficiency, respectively. In further experiments, the results of precision steering systems using RTK-GNSS and an optical camera guiding system additionally equipped with intra-row elements (e.g., finger weeders) were compared with the results of conventional hoeing. Mechanical weed control using automatic steering technology and an intra-row element (finger weeder) reduced the weed density by 89% compared with 68% in the conventional hoeing system. With respect to crop yields, statistical benefits of precision steering were not observed. However, the driving speed could be increased from 4 km h−1 in the conventional hoeing system to 10 km h−1 using the automatic steering systems. In an additional experiment, two cover crops species, rye (Secale cereale L.) and barley (Hordeum vulgare L.), were grown for preventive weed control in soybean production. The cover crops were transformed into a mulch layer using a roller-crimper immediately before soybean was sown using a no-tillage technique. Conventional tillage was performed to compare the systems with respect to their weed control efficiency, crop development and soybean yield. The results showed that the no-tillage system had a greater effect on suppressing summer annual weed species (Chenopodium album (L.), Echinochloa crus-galli (L.) P. Beauv. and Amaranthus retroflexus (L.)) than the tillage systems. Conventional tillage and reduced tillage showed increased suppression of the weed species Matricaria inodora (L.), Stellaria media (L.) Vill. and Sonchus arvensis (L.), which were present in the no-tillage system. However, in the conventional tillage and reduced tillage systems, an additional weed control treatment was necessary to suppress the summer annual weeds and ensure high yields. The cover crop rye resulted in weed control similar to that of barley in the no-tillage system. Despite the low weed density, the no-tillage system with a rolled cover crop showed a yield reduced of 47%, whereas the yield of the reduced tillage system was decrease by 23% compared with the conventional tillage system.
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    Achieving goals of ethical consumption : assessment of target criteria for the comparison of organic and locally purchased products with a modified scoring model
    (2015) Derksen, Dirtje Marie
    The increasing importance of ethical consumption is reflected through the rising numbers of consumers of ethically certified products. In this context the purchasing of organic products is widely regarded as major approach to consume in line with ethical criteria. However, also local purchasing gains importance for consumers. This study consequently intends to identify ethical consumption goals as related to organic and local purchasing, to reveal differences and commonalities between the two options and to assess the types of relationships that exist between the respective ethical criteria. Therefore, an integrated research review is conducted that aims on the development of a hierarchical framework of ethical consumption goals. The gathered information is furthermore analysed for its applicability in a modified scoring model that assesses the alignment of products and ethical consumption motives of individual consumers. It is revealed that even though consumers perceive a stronger linkage of certain ethical values with either local or organic purchasing, the consumption goals generally overlap and can thus be applied in a common model. However, the purchasing concepts appear to be unclear to consumers and linkages with social and non-ethical criteria increase the confusion and insecurity. Additionally, it is found that relationships between single ethical target criteria are not perceived as relevant and can thus be neglected in the model. Based on these results it is argued that the development of a model that supports purchasing decisions guided by ethical criteria is a viable approach, if it reflects all possible ethical consumption goals and provides sufficient transparency.
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    Feldstudie zur Eignung der Biophotonenmessung für die Differenzierung von ökologisch und konventionell erzeugten Hühnereiern
    (2009) Egerer, Ulrike; Grashorn, Michael
    Consumer demand for organic food is increasing. Conventional quality criteria are based on assay of individual chemical compounds, which depend much more on local conditions, climate and breed than on the production method. So alternatives need to be found to distinguish between organic and conventional food. Complementary approaches look at biological systems as a whole and focus on the inner structure of products. As shown in many studies, holistic criterions reflect differences in food quality, which are caused by the production method. F.A. POPP has rediscovered ultra weak light emissions that are presumed to originate from electromagnetic fields in living organisms. So-called 'biophotons' can be detected by highly sensitive photomultipliers as 'delayed luminescence' after illumination of the sample. Associated with living processes, the radiation reflects the state of the living tissue. In 2001 B. KÖHLER showed that egg yolks emit varying biophoton intensities depending on the husbandry system. Using standardized test conditions KÖHLER found that exposition to sunlight or to lighting that was similar to daylight, as well as feeding of green stuff, enhanced biophoton emission of yolks. The present investigation has been carried out under conditions of commercial egg production to discover whether biophoton emission is a suitable quality criterion for organic eggs. From July 2005 to November 2006, about 900 eggs have been collected in food stores and on farms. The biophoton intensity of each egg was determined and entered into a database according to its way of production (cage, deep litter, free-range, organic or from smallholders). The aim of this examination was to determine the differences in light emission of eggs originating from various production systems without standardized husbandry conditions. As a second project, a long-term observation has been conducted to see whether biophoton values of eggs remain stable over time. During the course of one year (from May 2006), biophoton emission has been measured each month. Samples have been taken from twelve hen houses with different husbandry systems: 2 houses with cage system, 4 with deep litter, 2 houses with free-range system and 4 organic farms ? adding up to more than 2,300 eggs. In addition to the measurement of biophoton emissions, conventional egg quality criteria have also been determined: egg mass, breaking strength of egg shell, albumen height, yolk color, proportion of yolk, fatty acid profile and lipid oxidation. Farmers have been interviewed about the age of their hens, flock size, lighting conditions and feed composition. Climatic conditions have been researched on the internet. It was expected that comparison of all collected data would give information on the origin and meaning of biophoton emission of egg yolks. In the present studies yolks were exposed to white light for 30 seconds. Delayed luminescence was detected for the duration of 60 seconds. The biophoton parameter used has been defined as the sum of light emission during the last 40 seconds of the measurement. Egg yolks from different animal husbandry systems differed in biophoton emissions. However, while conventionally produced egg yolks showed only minor differences, organic eggs as well as eggs from smallholders were characterized by clearly higher intensities. The long-term observation of yolks from 12 selected hen houses revealed great fluctuation of biophoton emissions over the course of the year. Nevertheless, it was remarkable that yolk samples with low contents of saturated fatty acids and high contents of polyunsaturated fatty acids showed the highest biophoton intensities. These samples originated from farms that offer both a green free range and feed including vegetables or dried grass. As KÖHLER had shown, feeding green stuff leads to higher light emissions of yolks and also influences the profile of fatty acids. Further examinations will be necessary to clarify the causality between fatty acid composition of the yolk and its biophoton emission. Another target of the described projects was to test the suitability of biophoton measurement for verifying the organic origin of eggs. In discriminant analyses egg samples of both studies were assigned to the categories 'organic' or 'conventional' according to their emission values. The hit ratio was about 70 %. This result is interesting considering the lack of techniques to distinguish between organically and conventionally produced eggs up to now. Optimization of measuring technique and procedure may improve the capability of the method. In any case, biophoton measurement could be used as a screening method. Detection of extremely low values would suggest a check of management conditions at the relevant farm, followed by comparison with standards for the respective animal husbandry system.
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    Highlighting outstanding beetroot varieties for the food industry - Evaluation of agronomic and compositional attributes of organically grown beetroot (Beta vulgaris L. subsp. vulgaris) varieties
    (2022) Yasaminshirazi, Khadijeh; Graeff-Hönninger, Simone
    The constant increase in awareness of the relationship between health and diet changed consumers’ perception of food and, accordingly, their food products’ choices. In this regard, the demand for foods, which promote mental and physical health and prevent specific diseases, has increased. Due to its high amount of bioactive compounds, which permits the reformulation of conventional products and transformation of them into functional foods, beetroot (Beta vulgaris L. subsp. vulgaris) was classified as a superfood. On account of the rising demand for organic food products, there is a necessity for varieties, which are adapted to the special requirements of organic farming. Alongside growing beetroot genotypes with desirable agronomic performances and promising contents of bioactive compounds, preserving the quality of harvested beetroots for an extended time can prolong the availability and use of this crop. Hence, affordable and easy-accessible possibilities for prolonging the shelf life of beetroot are required. This thesis aimed to disclose the genetic potential of a broad assortment of new and existing open-pollinated beetroot genotypes, which perform desirably in terms of agronomic and morphological traits (Publication I), compositional characteristics (Publication II), and quality stability (Publication III) under organic farming conditions. In this respect, in total, six genotype-screening field experiments were conducted in 2017 and 2018 at three different locations. Results of the first publication depicted a significant impact of genotype on the total and marketable yields, as well as most of the assessed morphological traits, including skin smoothness, corky surface, and beet shape uniformity. With the analysis of the contents of the total dry matter, total soluble sugar, nitrate, betalains, and total phenolic compounds in the second publication, significant differences were found between 15 studied beetroot genotypes. In addition, the outcome of the third publication demonstrated a significant effect of genotype on all measured compounds of 36 examined beetroot genotypes. Furthermore, the extent of change in the compositional quality during four months of cold storage was assessed for all studied genotypes. On account of the existing genetic variability in beetroot, it was concluded that the intended final utilization should be taken into account for the selection of suitable genotypes. In addition to the conducted assessments in Publication I – III, in the overall project framework from which this thesis was derived, the sensory characteristics of selected open-pollinated genotypes were compared with the commercially used varieties. Three sensory tests were carried out at the University of Hohenheim to determine consumers’ perception of the desired beetroot taste characteristics, including sweetness, aroma intensity, bitterness, earthy flavour, and the degree of acceptability. Generally seen, the studied open-pollinated genotypes indicated more sweetness and less bitterness compared to the F1 hybrid varieties. Furthermore, this thesis assessed the impact of nitrogen fertilisation level on selected compounds (nitrate and total soluble sugar contents) of specific genotypes (Borus, Ronjana, and Regulski Okragly) at the University of Hohenheim in 2018 and 2019. The outcomes indicated no significant influence of the N fertilisation rate on the total soluble sugar content. However, the impacts of fertilisation level and interactions between year and replication on the nitrate content were significant. Consequently, with adjusted N fertilisation, the amount of nitrate in beetroot can be directed in the desired direction based on the intended product (for example, sport drinks with high nitrate levels, and baby food with low nitrate levels). Nevertheless, in the pool of the investigated genotypes in Publication III, some genotypes possessed a comparable nitrate content with the highest values reached by using additional N-fertilisation in this experiment. To conclude, with the investigation of a broad assortment of beetroot genotypes, the findings of the present thesis revealed a high genetic variability regarding yield, morphological and compositional characteristics of beetroot, which provide new possibilities for farmers, the food industry, and consumers. To ensure the competency of the studied genotypes, further studies concerning the determination of other taste-relevant compounds like geosmin and disputable compounds such as oxalic acid are highly recommended. Moreover, to extend the use of the functional properties of fresh beetroot throughout the year, besides the selection of a suitable genotype, the external factors, such as storage conditions, should be optimized as well.