Browsing by Subject "Sugar beet"

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    Entwicklung eines GIS-gestützten schlagbezogenen Führungsinformationssystems für die Zuckerwirtschaft
    (2005) Laudien, Rainer; Doluschitz, Reiner
    The European Union aspires the GIS-based documentation of every agricultural area under cultivation from the year 2005 onwards. With this in mind, this thesis aims to design and develop a user-friendly Management Information System (MIS) for the sugar beet industry, which processes, visualizes, archives and documents geographical, remote sensing and attribute data. To meet the EU requirements the design of this "'Sugar beet Management Information System"' (SuMIS) is targeted at a GIS-based, modular, field-based approach which reflects the whole sugar beet supply chain. Therefore, the user of SuMIS will be able to geo-track and -trace every step from soil sampling to the beet delivery (fff = "from farm to factory"). By including and integrating GIS- and remote sensing data, SuMIS is a comprehensive System which can also be used as a Decision Support System within the Supply Chain Management. Due to the modular process-oriented design of SuMIS the potential of the system can be used by different users of the Supply Chain e.g. the field based documentation on the part of the farmer or the GIS-based decision making on the part of the sugar company. The design of SuMIS is based on the geo-datasets of two areas under investigation: Gemmingen/Kraichgau (area 1) and Plattling/Niederbayern (area 2). The dataset of area 1 represents the main part of the relational SuMIS geo-database and includes operational and external geo-data. The sugar beets in this area do not show plant diseases in general. Therefore, multi- and hyperspectral reflectance data of selected fields of area 2 is used to detect biotic growth-anomalies, general stress indicators and differences concerning plant vitalities and to create the respective spatial cognition. In order to collect the field data, a hyperspectral spectroradiometer (FieldSpec Handheld) is mounted stationary on a developed measurement device. This data is stored in a HTML-based spectral library. Besides that, multitemporal tractor- and airborne hyperspectral spectroradiometer measurements (GVIS, AVIS) are included to validate the ground based data. The reflection measurements are utilized to differentiate between healthy and unhealthy plants by using multispectral and hyperspectral vegetation indices. SuMIS includes new components which are developed and embedded by using the developer software "'Visual Basic"'. These are combined with existing functionalities in order to meet the EU GIS-requirements. Beside the functionalities which are used to analyze the hyperspectral data, two land-use classification methods are presented, applied and compared. Therefore, an object oriented (by using ERDAS Imagine® and a pixel based approach (by using eCognition) is employed to differentiate sugar beets from other crops in a simple and time efficient manner. QuickBird high resolution satellite form the basis for the accurate land use map. By applying the SuMIS functionalities and tools presented in this thesis, the users will be able to digitize their field data without any knowledge about GIS or geo-databases. Furthermore, storing and visualizing alphanumeric geodata is also possible by using these tools. Because of the information-specific structure of the geodata and its storage in several information layers, SuMIS is able to generate for instance mathematic calculations, clip-, merge- and join-procedures. This can be used for the spatial analysis or for creating new information layers. In this thesis such spatial GIS-results are shown in the context of a case study. The results of this case study indicate that the approaches developed lead to plausible results. Besides the description of the design of SuMIS and it's functionalities, the acceptance and survey of the expected individual benefits by potential selected users has been tested. Concerning the utility and value of SuMIS for the sugar beet industry, the functionalities are evaluated. The investigated results are discussed and perspectives for a broad application are described.
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    Entwicklung eines neuartigen Selektivhacksystems zur Unkrautkontrolle in Zuckerrüben
    (2022) Heinrich, Stefan; Köller, Karlheinz
    The production of organic sugar beets is one of the biggest challenges in organic farming. Due to its slow youth development, it is less competitive with seed weeds like white goosefoot, knotweed, or cockspur. The control in organic farming is mainly done mechanically with the help of hoeing systems between the rows and with harrow and finger weeders within the rows. The brittleness in the youth stages doesn’t allow an aggressive deployment of the in-row methods mentioned before, so the results stay far behind the expectations. To raise the yields and to make a harvest at least possible a manual removal of the weeds is essential. The effort on manual labor is settled between 50 to 250 hours per hectare. To reduce the costs for man-ual weeding some attempts were made to use automatic weeding systems from the vegetable production. Due to the small distances between the plants and the missing head start of the crop, the losses of the used systems were higher than the generated benefits. The main rea-sons for the fail belong to the plant detection system and the tool design. State-of-the-art tech-nology uses mainly color information and geometrical measurements to separate the plants from each other. Most of the tools use simple systems which open in front of a plant and close behind it. The driving speed is limited throughout the swing-in process. None of the tools that have been used so far have no “zero-intervention”, so the risk of the plants being buried in-creases in proportion to the driving speed. In the present dissertation, new concepts for online plant recognition are first developed. The detection of sugar beet is one of the most complex tasks in mechanical weed control. Due to the small distance between the plants and the special growth habits a precise detection of the center point is challenging. Common systems out of the industrial image processing field can-not be used directly, because of the small similarities between the plants. To get successful detection results important attributes like the distinctive leaf blade must be worked out. The main task is to develop a fully practical proofed selective weeding system. Therefore an evalu-ation between an autonomous platform and a tractor-mounted system has to be made. Due to the fact of the low power supply, it was decided to develop the tractor-mounted system. For the start, a common front weeding system is used to build the prototype. It is first used to collect image data. In the following steps, the platform is required to integrate the first in-row weeding tools. Starting with the results from the previous master thesis classical image recognition methods are used to develop different approaches for the detection of the center points. The approaches mainly differ in the plant growth stages. Until the two-leaf stage, binary operators deliver good results. Starting with the four-leaf stage, the new edge detection system for local-izing the centerline of the leaf reaches an accuracy of up to 20 mm. The single plant detection system achieves recognition rates from 50 % to 98 % depending on different growth stages and lighting conditions. Thanks to the grid seeding system it was possible to reach excellent detection rates even under a high degree of weed cover and harsh conditions. By sowing the plants in a triangular arrangement, it was possible to reduce the plant losses below 1 %. To bring the detection results to the ground the currently developed rotor weeding system from the University of Bonn was used as a starting point for developing new kinematics. It achieves throughout the hydromechanical contact pressure control a better ground contour following. It is also significantly less susceptible to difficult working conditions. Due to the inclination of the rotor, the so-called “zero-intervention” could be developed. Due to the adapted cutting angle to the row, the driving speed is completely compensated. This prevents the crops from covering with soil. The tool is hydraulically driven to create a robust and inexpensive platform. It should also be possible to use the components in future serial production. The cascade controller from the rotor achieved an angular accuracy below 0,7°. The plant positions primarily detected for the in-row system could also be used for the realization of a row guidance system. For this purpose, an active implement steering was designed in addition to the automatic tractor steer-ing system. This improved the guiding behavior of the front weeding system. In order to achieve the highest possible regulating effect for every growth stage, disc colters are used in combination with optional angled shares. In later stages goosefoot shares with optional wings can be used to reach a higher pile effect. Also, the in-row system is fully integrated into the tine carrier to obtain a compact unit. By linking the information from the sowing technology and the image processing, it has been possible to develop a highly robust and fail-safe system for mechanical weed control in organic sugar beet.
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    Entwicklung, Charakterisierung und Kartierung von Mikrosatellitenmarkern bei der Zuckerrübe (Beta vulgaris L.)
    (2001) Dörnte, Jost; Geiger, Hartwig H.
    Simple sequence repeats (SSRs) or microsatellites were isolated from a sugarbeet (Beta vulgaris L.) genomic phage library. The size-fractionated library was screened for the occurrence of the motifes (GA)n, (GT)n, (TGA)n, (AGA)n and (CCG)n. The motifes (GA)n and (GT)n were found to occur most frequently in the sugarbeet genome (every 225 kb). In contrast, the trimer motifes were half as frequent (every 527 kb). A total of 217 microsatellite sequences were found in the sequenced clones. Most of the repeats were imperfect and/or compound. Sequence comparison revealed that 23% of the clones wich containing the (GT)n motif are variants of a previously described satellite DNA (SCHMIDT et al. 1991). Of 102 primer pairs tested on sugarbeet DNA, 71 gave a single product in the expected size. On 23 sugarbeet samples 64 of the 71 SSR-markers reveald length polymorphisms. The number of detected alleles per marker ranged from 2 to 13 (average 4,9) and the PIC-values ranged from 0,17 to 0,86 (average 0,58). A cluster analysis of the 23 samples confirms the pedigree data. The developed SSR markers were compared with RFLP and AFLP markers. Therefore nine sugarbeet lines, each with five single plants per line, were analysed. The SSR analyse shows the lowest similarity between the nine lines. The similarity inside the lines revealed no differences between the marker assays. Thirtythree SSR markers were genetically mapped into the RFLP framework maps of 2 F2-populations. The markers are randomly distributed over eight linkage groups of sugar beet.
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    Evaluation of the new cropping practices in sugar beet (Beta vulgaris L.) cultivation in the central black soil region of Russian Federation
    (2019) Bezhin, Kostyantyn; Gerhards, Roland
    In recent years Russian sugar production has exceeded the country needs with a surplus of 500.000 tons. Sugar producers and traders are forced to start trading on the global markets. However, ineffective production, caused by low yields of sugar puts the price of Russian sugar 35 to 50 % higher than the leading sugar exporters. Weeds belong to one of the main factors reducing sugar beet yield. Weeds that survive control operations may cause significant crop yield reductions. Rapid emergence and homogeneous crop stand are very important for competition with weeds. At the same time, the crop may be suppressed by selective herbicide application, if herbicides are applied during suboptimal weather conditions. This study evaluated glyphosate-tolerant sugar beet technology and seed priming for the possibility to increase the productivity of sugar beet cultivation. A series of studies were carried out in different environments in Germany and in Russian Federation. The scope of the studies was dealing with: i) comparison of the conventional weed control technology with technology, based on glyphosate applications; ii) a study of the crop weed interaction in German environment and in the environment of the Central black soil region of the Russian Federation; iii) tests of sugar beet seed priming for the speed of germination by means of growth chamber test, and for the speed of emergence in the soil seedbed, by means of greenhouse and field experiments. The results of the conducted experiments are concentrated in three scientific articles that have been published in the international peer-reviewed journals: The purpose of the first article was to analyse the weed control efficacy of weed control schemes with one, two and three applications of glyphosate and compare it with the conventional weed control technology. The results show that the application of glyphosate supplied significantly higher efficacy of weed control than conventional herbicides. In five out of 7 experiments single application of glyphosate gave the same weed control efficacy as two or three applications. No significant differences in weed control efficacy were observed between two different dosages of glyphosate – 900 and 1350 g a.e. ha-1. The variants treated with conventional herbicides and with two and three glyphosate applications showed no significant differences in white sugar yield. In one location, the variant with one application of glyphosate resulted in lower white sugar yield due to delayed application of herbicide, and longer time of crop and weed interference. The aim of the second article was to study the yield loss caused by the competition with weeds in different environments. In the Russian locations Chenopodium album L. and Amaranthus retroflexus L. caused serious yield reduction already at low plant densities. White sugar yields harvested at Russian locations were approximately 45 % lower than in German locations. At Russian locations 50 % of the maximum weed population has caused more than 80 % yield reduction. Relative weed cover was the best predictor of the sugar beet yield loss. Weed biomass and weed density gave less accurate predictions. The third article was focused on testing of priming technology on the seed performance and crop establishment. In the controlled environment, primed seeds needed 10 days to reach full germination percentage of the seeds, for not primed seeds it took between 12 and 14 days. Primed seeds produced significantly larger area of plant foliage area and amount of dry biomass than non-rimed seeds. In uncontrolled environments, findings of previous experiments could not be confirmed. Priming did not influence the weed suppressive ability of the crop and the white sugar yield. The general conclusion of this dissertation is that GT technology may help to improve the profitability of sugar beet cultivation for Russian growers by reducing the number of herbicide applications and increase weed control efficacy. Seed priming can give benefits for crop establishment, however only under specific environmental conditions.
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    Integrated weed control in sugar beet (Beta vulgaris), using precision farming technologies and cover cropping
    (2017) Kunz, Christoph; Gerhards, Roland
    Weed control is one of the major challenges in sugar beet (Beta vulgaris) production worldwide. Due to the high flexibility and low costs, herbicide applications are the common agricultural practice for successful weed control. Yet, due to European and national restrictions, farmers are forced to substitute their herbicide input in order to reduce the chemical influence on the environment. Beside chemical weed control systems, integrated weed management (IWM), can be an alternative, to reduce the chemical preponderance. The five essential parts in composing a successful IWM system are: i) cover crops (CC) and ii) resulting mulch residues which can decrease the weed infestation prior to the actual crop establishment, iii) living mulches which can suppress weeds during the crop growth period and iv) precision mechanical weed control which can provide herbicide reductions. Last but not least v) herbicide applications should be optimized with sensor technologies to identify and reduce stress on crops. In the current study, all the named aspects of IWM were examined in sugar beets. In order to accomplish that, the following research objectives were investigated and answered in the course of the papers composing this thesis: • Evaluation of the suitability of CC and CC mixtures for weed suppression prior to sugar beet sowing • Assessment of differences in sugar beet emergence, weed control and biomass under different CC mulches • Application of living mulches and measurement of their weed control efficacy during the sugar beet growth period • Evaluation of mechanical weed control along with chemical band spraying compared to an overall herbicide application • Determination of the weed control efficacy of mechanical weeding by using visual sensors and GNSS-RTK • Investigation of the feasibility of intra-row mechanical weed control, its prerequisites and limitations • Detection of responses to herbicides by using chlorophyll fluorescence imaging technology 1st paper: Field and laboratory experiments were conducted to investigate the competitive and biochemical weed suppressive ability of CC. Applied aqueous CC extracts in germination tests inhibited weed growth and potential allelochemicals were identified. In the field all CC either in mixture- or mono-cultivation were able to suppress weeds compared to an untreated control by 66%. In the 2nd and 3rd paper sugar beet plant emergence was investigated in greenhouse and field experiments, in order to evaluate the influence of various CC mulches on weed suppression. Different CC mulches reduced weed germination successfully. During one dry growing season sugar beet emergence was enhanced by increased soil moisture due to the existence of a CC mulch layer compared to uncovered soil. Our findings suggest that CC mulch layers can substantially effect crop and weed development within the field. To assess the weed suppressive ability of living mulches in sugar beets, field studies were carried out at four sites in southern Germany, presented in the 4th paper. Results show that living mulches can reduce the total amount of different weed species in the inter-row area up to 71%. The white sugar yield was increased in average by 42% with the existence of living mulch as compared to the untreated control. In the 5th, 6th and 7th paper sensor technologies were used for mechanical weed control combined with chemical band application to reduce the herbicide input, with similar weed control results to the overall chemical application. Sensor based, mechanical precision steering technologies, reduced weeds more effectively than when compared to manual operator guidance. This is due to accurate fast driving speeds close to the crop area. Intra row elements (finger weeder, rotary harrow, torsion weeder, heap element) for mechanical weed control showed effective weed suppression. Nevertheless, suitable soil and weather conditions for mechanical weed control were not always given, which can result in an efficacy loss. Finally, in the 8th paper, a portable sensor, based on chlorophyll fluorescence imaging, was used in greenhouse experiments to investigate the response of plants after herbicide application. Various active ingredients have shown different damage concerning the photosystem II. The use of this sensor can quantify phytotoxic effects due to herbicides and can help to find the most suitable herbicide application date, active ingredients or herbicide mixture. The overall result of this dissertation reveals the great potential of CC, living mulches, precision mechanical methods and sensor technologies as part of an IWM system in sugar beet production.
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    Nachhaltige Biogasproduktion unter besonderer Berücksichtigung des Einsatzes von Zuckerrüben und Grünlandaufwuchs sowie der Gärrestverwertung
    (2017) Auburger, Sebastian; Bahrs, Enno
    The present cumulative dissertation assesses the sustainability of biogas production in Germany from different points of view. A special focus is brought to sugar beets and grassland as a biogas feedstock as well as to biogas residue utilization. Chapter 2 presents an approach of manure distribution within regions based on municipality biogas and livestock production data. The developed algorithm distributes nutrients of nutrient surplus municipalities to municipalities with nutrient adsorption capacity within a study area (Lower Saxonia and North Rhine-Westphalia). It was shown that farmers and biogas producers will be confronted with higher manure and biogas digestate disposal costs. Chapter 3 enlarges the view by taking pig producers and experts interviews into consideration. Chapter 4 presents an approach to determine the regional biogas feedstock input based on regional agricultural production cost data and almost 8,000 biogas plants in Germany. By using a linear optimization approach regional feedstock inputs are calculated. Furthermore greenhouse gas emissions of power production based on biogas are estimated. Chapter 5 enlarges the modeling approach by an energy balancing tool and assesses sugar beets as an energy crop for biogas production in detail. Therefore different scenarios are taken into account. Silage corn was the most competitive feedstock over almost every region in Germany. Round about 160 kg CO2eq per kWh from biogas production were calculated, which is a significant lower value in comparison to greenhouse gas emissions from current power mix in Germany. Chapter 6 focuses on grassland as a biogas feedstock. Based on data availability calculation had to be restricted to Federal States of Schleswig-Holstein, Lower Saxonia and Bavaria. Results show that grassland is a competitive biogas feedstock in regions, which are characterized by unfavorable production circumstances of silage corn and only if for grassland favorable scenario assumptions are chosen.
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    Optimierung der Konservierung und der anaeroben Konversion von Zuckerrüben zur Nutzung in flexiblen Biogassystemen
    (2019) Kumanowska, Elzbieta Joanna; Jungbluth, Thomas
    Biogas production is well suited to balance the fluctuating electricity production from the renewable energy sources sun and wind. Due to the currently unfavorable conditions in the renewable energy supply policy in Germany, time is spent looking for alternatives for electricity production from biogas. The preparation for natural gas quality for fuel production or for natural gas grid injection would be such an alternative but requires process improvements to reduce costs. One approach would be to use two-stage biogas production, as there is a high methane content in the produced biogas, thus reducing the cost of processing to natural gas quality. A suitable substrate for both applications would be sugar beet, due to its fast biodegradability and good methane yields. The preservation of sugar beets for year-round provision has so far been problematic because it can cause high losses. In addition, it can cause process biological problems, if it is used in high proportions. In the context of this work, the use of sugar beets for biogas production was tested using these promising methods. For this purpose, storage experiments were carried out and new storage methods for the practice were developed and tested, all of which are primarily aimed at the use of sugar beet silage effluent. Practice-based point-feeding experiments were used to test its suitability for demand-oriented biogas production. Furthermore, the optimization of the two-stage biogas production from sugar beet was carried out. For this purpose, an experiment was conducted in the biogas laboratory to determine the optimum hydrolysis pH during the fermentation of sugar beet silage. In order to develop a new, optimal method for the storage of sugar beets, further knowledge regarding the process of ensiling sugar beets, the silage effluent formation and the influencing parameters was required. Therefore, mass balances were carried out in the column experiments in the laboratory of the State Institute of Agricultural Engineering and Bioenergy to determine the influence of the parameters stack height and sugar beet chips size on the silage effluent formation during the ensiling process of the chopped sugar beets. Silage effluent was produced in amount about 50% of the stored mass. About half of the silage effluent production took place during the first three weeks of storage. The produced silage effluent was characterized over the entire storage time by extremely high COD-values of 250 g l-1. The parameters stack height and particle size had no significant influence on the mass balance. On the basis of the results of the column experiments, a mobile and a stationary method on a technical scale for the storage of sugar beets were investigated. In the mobile variant, the flexible tanks, washed, chopped sugar beet was ensiled. Considering the goal to maximize silage effluent yield, the ensiling of chopped sugar beet was superior to the ensiling of whole beet. Also, soil removal is advantageous for silage effluent production as well as for silage quality. Storage in the stationary pit silos proved to be technically advantageous, and it promises to be well suited for the intended applications when in combination with washed and chopped beets. The application of produced silage effluent for demand-oriented biogas production was carried out at the research biogas plant of the University of Hohenheim. The system’s response observed as an increase in biogas production took place a few minutes after the point feeding with sugar beet silage effluent. As a result of the point feeding, the produced volumetric biogas flow rate was doubled without endangering the stable biogas plant operation. The maximum gas production was reached after about 1:45 h. In this work, a concept for the use of sugar beet for the production of high calorific biogas was tested, based on the two-stage anaerobic digestion. The experimental plants consisted of a horizontal stirred tank reactor for hydrolysis and two combined fixed bed reactors used as a methane reactor. The influence of the pH value in the hydrolysis stage on the anaerobic digestion of sugar beet silage was tested. High degradation rates and methane yields demonstrated the overall suitability of this system for sugar beet silage digestion. The best compromise of the process parameters degradation rate in complete system and methane yield was achieved at a pH value of 6. The investigation carried out for this work shows, that the concept of a new sugar beet storage method, with a focus on sugar beet silage effluent production, is well suited for demandoriented biogas production as well as for the production of a high calorific biogas by means of the two-stage biogas process.
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    Physiological and metabolic adaptation of Beta vulgaris and Suaeda maritima to salinity and hypoxia
    (2022) Behr, Jan Helge; Zörb, Christian
    Soils with high salinity are often also affected by waterlogging with hypoxic conditions in the root zone, which severely reduces plant growth and crop yield. The combination of salinity and hypoxia generates an intense stress for the plant: On the one hand, hypoxic conditions at the root level cause a severe energy deficit due to the inhibition of oxidative phosphorylation, on the other hand, energy-consuming tolerance mechanisms have to be maintained to cope with salt stress. To better understand the tolerance mechanisms to combined saline and hypoxic conditions, the metabolic and physiological adaptation capacity of the model halophyte Suaeda maritima, typically found in flooded saline soils, and the closely related sugar beet (Beta vulgaris L.) were analysed. Salt tolerant plants are characterised by their ability to tolerate high Na+ and Cl- concentrations without being damaged by ion toxicity. The basis of this tolerance is primarily osmotic adaptation, the compartmentalisation of ions in cell organelles and the ability to replace K+ with Na+ in important cellular processes. Li+ has similar physico-chemical properties to Na+ and K+, but forms complexes with organic and inorganic anions more readily than other alkali metals. Therefore, Li+ can displace metals during the uptake and translocation by the plant and at enzymatic binding sites, which impairs enzyme activity and can lead to toxic effects. The effects of different cations with similar physicochemical properties on their accumulation pattern at high and low osmolarity were investigated to determine whether Li+ toxicity could be mitigated by competitive uptake of K+ and Na+. Hydroponic culture experiments with increasing salt concentration demonstrated the ability of S. maritima and B. vulgaris to tolerate high salt concentrations by maintaining ion homeostasis and high tissue tolerance to Na+ accumulation. An increased Na+/K+ ratio under hypoxic conditions indicates that an energy shortage caused by oxygen depletion in the root impairs Na+ exclusion and K+ uptake, thereby increasing the ionic imbalance under hypoxic conditions. The metabolic profile showed a tissue-specific response to salinity and hypoxia: The root metabolism is mainly influenced by hypoxia, inhibiting oxidative phosphorylation, while at the same time glycolysis is enhanced to maintain ATP production. The enhanced accumulation of amino acids and TCA cycle intermediates suggests that a partial flow of the TCA cycle fuelled by the GABA shunt may play a crucial role in the recovery of reduction equivalents for ATP production by glycolysis, thereby sustaining energy-intensive cellular processes under hypoxic conditions. As a consequence to the high Na+ accumulation in the shoots, the metabolic profile of young and mature leaves is mainly influenced by salt stress, which triggers the accumulation of compatible solutes for osmotic adjustment and ROS scavenging mechanisms. To achieve tolerance to high salinity, energy consumption rises. Hence, the biomass increase of B. vulgaris stagnates at 200 mM NaCl. In contrast, S. maritima shows its optimal growth at the same salinity range, which reflects the higher adaptability of the halophyte to saline conditions. Different mechanisms in the shoot and root lead to an accumulation of proline, which contributes to the increased tolerance to combined salinity and hypoxia, as proline stabilises membranes and proteins under salt stress and scavenges increased ROS formation induced by hypoxia. High ion accumulation in combination with hypoxic conditions enhances ROS formation in the shoots, leading to light-induced pigment degradation in S. maritima, which is mitigated by enhanced proline biosynthesis in the chloroplasts. In contrast, proline accumulation in the root is not exclusively the result of enhanced proline biosynthesis, but of inhibited proline degradation due to the low availability of reduction equivalents when salinity and hypoxia are combined. The accumulation of Li+ is relatively low in comparison to Na+ and K+, as B. vulgaris strongly limits the Li+ uptake via the transpiration stream to avoid toxic Li+ concentrations in the leaves. High concentrations of Li+ combined with Na+/K+, increase Li+ accumulation in leaves and cause growth inhibition as well as the formation of necrotic tissue, indicating low tissue tolerance to Li+ and severe stress. The application of equimolar concentrations of Na+ and K+ has no effect on Li+ accumulation and ion toxicity, suggesting that Li+ uptake is independent of Na+ and K+ cation channels and that Li+ toxicity is not mainly caused by the displacement of K+ at enzymatic binding sites.
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    Unkrautbekämpfung in Zuckerrüben - Ermittlung der Kritischen Periode
    (2003) Kobusch, Henner; Hurle, Karl
    Early leaf stages of sugar beet are very sensitive to weed competition, which is a major reason for the absence of thresholds for weed control in sugar beet. In combination with non-selective herbicides, the use of herbicide resistant sugar beets appears to allow the control of weeds at a later date than usual applications of common selective herbicides. Therefore, it is necessary to know the critical period, in which the crop should be weed free in order not to loose yield. The influencing factors of the critical period are the moment until weed can be tolerated (beginning of the critical period) and the moment after weed can be tolerated (end of the critical period). The primary objective of the present work was the establishment of a parameter, which would allow a determination of the critical period independent of location and season. Therefore, triannual field trials were carried out at three different sites in the Ukraine and in Stuttgart-Hohenheim in order to evaluate the suitability of different parameters. In addition, by use of a glufosinat resistant sugar beet transformant, the practicability of the critical period was investigated. Application of the critical period and moreover the definition of a general period threshold requires a reference value defining the beginning and end of the critical period which is both independent of location and season. The primary aim of this work was to establish a parameter, which fulfills this condition. All parameters relate to the growth of sugar beet or of the weed quantify their interaction. The following parameters were investigated: the leaf stage of the sugar beet, the weed and sugar beet coverage level, the relative weed coverage, the temperature sum and the intensity of weed shading of the beets. The investigation took place at three separate sites in the Ukraine and in Stuttgart-Hohenheim enabling the effect of different sites to be taken into account. A uniform sugar beet leaf stage until and after weeds could be tolerated was not found. The leaf stage until weeds could be tolerated varied between the 2 and 10 leaf stage. Similarly the leaf stage after which the weeds could be tolerated varied between the 2 and 12 leaf stage of the beet. A uniform and therefore location and year-independent degree of sugar beet coverage and weed coverage relating to leaf stage was not found at the beginning of the critical period at the Hohenheim site (1999 and 2000) and Poltava (1999) in the Ukraine. The degree of weed cover varied at the beginning of the critical period between 96.7% and 66.5% in Hohenheim. The same applies to the degree of sugar beet coverage which varies between 5.3% and 15%. The difference between the two levels of coverage is almost completely compensated by the parameter relative weed coverage. At the Hohenheim site it only varied between 94.8% and 84.5%. The minimum value was found at Poltava with 83.8%. On this basis, a maximum relative weed coverage of 83 % can be tolerated without significant yield loss. Herewith, a decisive parameter is defined as a measure for timing weed control in sugar beets. However, an important requirement is the availability of efficient control methods at this certain point of time. In a further step an attempt was made to apply the critical period in relation to the leaf stage of the beet by using a glufosinate resistant sugar beet transformant. In no trail it could be waited with glufosinate applications until the beginning of the critical period. The latest leaf stage, when glufosinate application had to start in Poltava and Vinnitsa was the 6-leaf stage, whereas the critical period began at the 10- or 12-leaf stage. A limiting factor for the definitive application of the beginning of the critical period was shown in the field trials by a decreasing tolerance of the glufosinate resistant transformant at ever later leaf stages of beet development. Prediction model investigations confirmed this correlation. In addition to the effect of the leaf stage the effect of weather conditions was also apparent. The increase in air humidity from 50 % to 80 % led to an increase in NH3 concentration in the resistant transformant, regardless of its leaf stage. NH3 is found in non-resistant plants due to the inhibition of glutamine-synthetase by glufosinate, which leads to cell death. The largest increase in NH3 when the air humidity was increased from 50 % to 80 % occurred at the youngest leaf at the 6-leaf stage. In addition to the dependency of NH3 concentration on leaf stage the effect of leaf age was also apparent. Concluding, the control of weeds, related to the leaf stage of glufosinate resistant sugar beet, has to be done before the critical period begins. Unfortunately, technologies, which offer the possibility to control weeds by an integration of the critical period, are so far not available.
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    Untersuchungen zum Herbizidstress in Zuckerrüben mit drei feldtauglichen optischen Sensoren und Methoden der Bildanalyse
    (2014) Roeb, Johannes
    Weed management in sugar beets is based on the repeated use of herbicide mixtures after crop emergence. Due to the limited selectivity of active ingredients, herbicide treatments not only control the weeds but will reduce the growth of sugar beets also. Yield losses due to herbicide stress are expected to range between 5-15%. Using optical sensors is a nondestructive method to assess changes in reflection, leaf fluorescence or chlorophyll fluorescence kinetics induced by herbicides. To evaluate the applicability of three optical sensors for assessing herbicide stress and to measure the influence of herbicides and herbicide mixtures on sugar beets, a pot experiment was performed at the University of Hohenheim, Germany. Sugar beets were grown under natural light and temperature conditions and treated with the active ingredients metamitron, phenmedipham, desmedipham, ethofumesate, triflusulfuron-methyl and dimethenamid-P in their commercially available formulation and practical dosage. In total five single herbicides as well as five different herbicide mixtures were applied in the cotyledon stage (EC 10), the two-leaf stage (EC 12) or the four- to six-leaf stage (EC 14/16) of sugar beets. Stress reactions were monitored with three optical sensors: Images of a digital camera (Canon EOS 1000D) were used to determine leaf coverage area, plant shape and leaf color. Measurements were performed about every second day and a growth index had been calculated. A multispectral fluorometer (FORCE-A MULTIPLEX®) was used to detect the blue-green fluorescence, red fluorescence and far-red fluorescence and to calculate fluorescence indices. A portable imaging sensor of chlorophyll fluorescence kinetics (WALZ IMAGING PAM) was used on a daily basis to determine changes in the maximum quantum efficacy (Fv/Fm) induced by herbicide treatments. Four respectively two weeks after the treatment sugar beets were harvested for dry matter analysis. For each of the herbicide treatments and for each of the three application dates five Mitscherlich pots were used for replication. Each pot had about four sugar beet plants. Based on digital imaging it was possible to measure leaf coverage area and determine growth depressions induced by herbicide treatments containing mixtures of the active ingredients phenmedipham, desmedipham and ethofumesate. Herbicide mixtures with more active ingredients increased the stress reaction of sugar beets. Differentiation between untreated plants and sugar beets treated with different herbicides or mixtures was possible a few days after application. Results were correlated with dry matter. Changes in plant shape parameters indicated a delayed development of herbicide treated plants. Higher red content of leaf color was attributed to a relative loss of chlorophyll. Measurements with the FORCE-A MULTIPLEX® fluorometer detected an increase in red and far-red fluorescence but not blue-green fluorescence within 1-2 days after treatments with the aforementioned mixture of active ingredients. About the same trends were found at all application dates. Most fluorescence values were affected by growth stage and leaf area of sugar beets. Thus, although differences between treated and untreated plants were strong, it was not possible to discriminate between stress reactions on different herbicide treatments. Based on the maximum quantum efficacy (Fv/Fm) measured with the WALZ IMAGING-PAM chlorophyll fluorescence sensor previous studies, describing the time course of stress reaction on application of PSII-inhibitors in sugar beets were confirmed. After a strong decrease of Fv/Fm within one day, recovery to the initial value was observed within ten days. Quantification of herbicide stress induced by PSII-inhibitors was possible due to different intensities and durations of the stress reaction. Photochemical stress response to treatments with metamitron or chloridazon was lower than with products containing phenmedipham or desmedipham. Stress reaction on herbicide mixtures not only depended on content of PSII-inhibitors but also on formulation. Weather conditions were more important than the sugar beet development stage considering the stress reaction. Observations from previous studies, indicating an increase in herbicide stress after precipitation and at low temperatures, were also confirmed in this study. Differences in stress reactions of cotyledons and first true leaves can be explained by a higher uptake of herbicides in young tissues. The influence of other herbicides, mixtures, dosages and formulations on herbicide stress in sugar beets has to be further investigated. Moreover the complex interrelations between sugar beet development stage, weather conditions and stress reaction could only be investigated in systematic field trials. For the measurement of stress reactions on herbicides the described optical sensors and methods can be used, each having different advantages and disadvantages.