Browsing by Subject "Feldversuch"

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Biometrical approaches for analysing gene bank evaluation data on barley (Hordeum spec.)
(2007) Hartung, Karin; Piepho, Hans-Peter
This thesis explored methods to statistically analyse phenotypic data of gene banks. Traits of the barley data (Hordeum spp.) of the gene bank of the IPK-Gatersleben were evaluated. The data of years 1948-2002 were available. Within this period the ordinal scale changed from a 0-5 to a 1-9 scale after 1993. At most gene banks reproduction of accessions is currently done without any experimental design. With data of a single year only rarely do accessions have replications and there are only few replications of a single check for winter and summer barley. The data of 2002 were analysed separately for winter and summer barley using geostatistical methods. For the traits analysed four types of variogram model (linear, spherical, exponential and Gaussian) were fitted to the empirical variogram using non-linear regression. The spatial parameters obtained by non-linear regression for every variogram model then were implemented in a mixed model analysis and the four model fits compared using Akaike's Information Criterion (AIC). The approach to estimate the genetical parameter by Kriging can not be recommended. The first points of the empirical variogram should be explained well by the fitted theoretical variogram, as these represent most of the pairwise distances between plots and are most crucial for neighbour adjustments. The most common well-fitting geostatistical models were the spherical and the exponential model. A nugget effect was needed for nearly all traits. The small number of check plots for the available data made it difficult to accurately dissect the genetical effect from environmental effects. The threshold model allows for joint analysis of multi-year data from different rating scales, assuming a common latent scale for the different rating systems. The analysis suggests that a mixed model analysis which treats ordinal scores as metric data will yield meaningful results, but that the gain in efficiency is higher when using a threshold model. The threshold model may also be used when there is a metric scale underlying the observed ratings. The Laplace approximation as a numerical method to integrate the log-likelihood for random effects worked well, but it is recommended to increase the number of quadrature points until the change in parameter estimates becomes negligible. Three rating methods (1%, 5%, 9-point rating) were assessed by persons untrained (A) and experienced (B) in rating. Every person had to rate several pictograms of diseased leaves. The highest accuracy was found with Group B using the 1%-scale and with Group A using the 5%-scale. With a percentage scale Group A tended to use values that are multiples of 5%. For the time needed per leaf assessment the Group B was fastest when using the 5% rating scale. From a statistical point of view both percent ratings performed better than the ordinal rating scale and the possible error made by the rater is calculable and usually smaller than with ratings by rougher methods. So directly rating percentages whenever possible leads to smaller overall estimation errors, and with proper training accuracy and precision can be further improved. For gene banks augmented designs as proposed by Federer and by Lin et al. offer themselves, so an overview is given. The augmented designs proposed by Federer have the advantage of an unbiased error estimate. But the random allocation of checks is a problem. The augmented design by Lin et al. always places checks in the centre plot of every whole plot. But none of the methods is based on an explicit statistical model, so there is no well-founded decision criterion to select between them. Spatial analysis can be used to find an optimal field layout for an augmented design, i.e. a layout that yields small least significant differences. The average variance of a difference and the average squared LSD were used to compare competing designs, using a theoretical approach based on variations of two anisotropic models and different rotations of anisotropy axes towards field reference axes. Based on theoretical calculations, up to five checks per block are recommended. The nearly isotropic combinations led to designs with large quadratic blocks. With strongly anisotropic combinations the optimal design depends on degree of anisotropy and rotation of anisotropy axes: without rotation small elongated blocks are preferred; the closer the rotation is to 45° the more squarish blocks and the more checks are appropriate. The results presented in this thesis may be summarised as follows: Cultivation for regeneration of accessions should be based on a meaningful and statistically analysable experimental field design. The design needs to include checks and a random sample of accessions from the gene pool held at the gene bank. It is advisable to utilise metric or percentage rating scales. It can be expected that using a threshold model increases the quality of multivariate analysis and association mapping studies based on phenotypic gene bank data.
Development and assessment of a multi-sensor platform for precision phenotyping of small grain cereals under field conditions
(2014) Busemeyer, Lucas; Würschum, Tobias
The growing world population, changing food habits especially to increased meat consumption in newly industrialized countries, the growing demand for energy and the climate change pose major challenges for tomorrows agriculture. The agricultural output has to be increased by 70% by 2050 to achieve food and energy security for the future and 90% of this increase must be achieved by increasing yields on existing agricultural land. Achieving this increase in yield is one of the biggest challenges for the global agriculture and requires, among other things, an efficient breeding of new, higher-yielding varieties adapted to the predicted climate change. To achieve this goal, new methods need to be established in plant breeding which include efficient genotyping and phenotyping approaches of crops. Enormous progress has been achieved in the field of genotyping which enables to gain a better understanding of the molecular basis of complex traits. However, phenotyping must be considered as equally important as genomic approaches rely on high quality phenotypic data and as efficient phenotyping enables the identification of superior lines in breeding programs. In contrast to the rapid development of genotyping approaches, phenotyping methods in plant breeding have changed only little in recent decades which is also referred to as phenotyping bottleneck. Due to this discrepancy between available phenotypic and genotypic information a significant potential for crop improvement remains unexploited. The aim of this work was the development and evaluation of a precision phenotyping platform for the non-invasive measurement of crops under field conditions. The developed platform is assembled of a tractor with 80 cm ground clearance, a carrier trailer and a sensor module attached to the carrier trailer. The innovative sensors for plant phenotyping, consisting of several 3D Time-of-Flight cameras, laser distance sensors, light curtains and a spectral imaging camera in the near infrared reflectance (NIR) range, and the entire system technology for data acquisition were fully integrated into the sensor module. To operate the system, software with a graphical user interface has been developed that enables recording of sensor raw data with time- and location information which is the basis of a subsequent sensor and data fusion for trait determination. Data analysis software with a graphical user interface was developed under Matlab. This software applies all created sensor models and algorithms on sensor raw data for parameter extraction, enables the flexible integration of new algorithms into the data analysis pipeline, offers the opportunity to generate and calibrate new sensor fusion models and allows for trait determination. The developed platform facilitates the simultaneous measurement of several plant parameters with a throughput of over 2,000 plots per day. Based on data of the years 2011 and 2012, extensive calibrations were developed for the traits plant height, dry matter content and biomass yield employing triticale as a model species. For this purpose, 600 plots were grown each year and recorded twice with the platform followed by subsequent phenotyping with state-of-the-art methods for reference value generation. The experiments of each year were subdivided into three measurements at different time points to incorporate information of three different developmental stages of the plants into the calibrations. To validate the raw data quality and robustness of the data collection and reduction process, the technical repeatability for all developed data analysis algorithms was determined. In addition to these analyses, the accuracy of the generated calibrations was assessed as the correlations between determined and observed phenotypic values. The calibration of plant height based on light curtain data achieved a technical repeatability of 0.99 and a correlation coefficient of 0.97, the calibration of dry matter content based on spectral imaging data a of 0.98 and a of 0.97. The generation and analysis of dry biomass calibrations revealed that a significant improvement of measurement accuracy can be achieved by a fusion of different sensors and data evaluations. The calibration of dry biomass based on data of the light curtains, laser distance sensors, 3D Time-of-Flight cameras and spectral imaging achieved a of 0.99 and a of 0.92. The achieved excellent results illustrate the suitability of the developed platform, the integrated sensors and the data analysis software to non-invasively measure small grain cereals under field conditions. The high utility of the platform for plant breeding as well as for genomic studies was illustrated by the measurement of a large population with a total of 647 doubled haploid triticale lines derived from four families that were grown in four environments. The phenotypic data was determined based on platform measurements and showed a very high heritability for dry biomass yield. The combination of these phenotypic data with a genomic approach enabled the identification of quantitative trait loci (QTL), i.e., chromosomal regions affecting this trait. Furthermore, the repeated measurements revealed that the accumulation of biomass is controlled by temporal genetic regulation. Taken together, the very high robustness of the system, the excellent calibration results and the high heritability of the phenotypic data determined based on platform measurements demonstrate the utility of the precision phenotyping platform for plant breeding and its enormous potential to widen the phenotyping bottleneck.
Meßverfahren zur Beurteilung des Stoffeignschaftseinflusses auf die Leistung der Trennprozesse im Mähdrescher
(1992) Beck, Thomas
Der bei der Korn/Stroh- und bei der Korn/Spreu-Trennung im Mähdrescher auftretende Kornverlust ist eine stetig wachsende Funktion des Durchsatzes. Die Trennprozeßleistung ist der Massendurchsatz, bei dem ein zuverlässiger Kornverlust überschritten wird. Parameter der Funktion sind die konstruktive Gestaltung der Trennelemente und die Stoffeigenschaften des Erntegutes. Für denselben Mähdrescher werden deshalb in verschiedenen Jahren oder Feldern unterschiedliche Leistungen festgestellt. Der Einfluß der Stoffeigenschaften muß deshalb quantitativ beurteilt werden. Um den aufwendigen Einsatz eines Vergleichsmähdreschers zu vermeiden, werden wesentlich einfachere und genauere Meßverfahren für Stoffeigenschaften vorgeschlagen. Aus der Anaalyse der Trennprozesse im Mähdrescher werden zwei Meßverfahren für technologische Stoffeigenschaften hergeleitet. Für die Korn/Stroh-Trennung wird eine Zeitkonstante der Entmischung (Durchdringungszeit) bestimmt, für die Korn/Spreu-Trennung wird die Fluidisierungsgeschwindigkeit des Gutgemisches gemessen. Korrelationen zwischen Änderungen dieser Stoffeigenschaften und Leistungsänderungen der Trennprozesse eines Versuchsmähdreschers werden im Feldversuch experimentell bestätigt.
Pflanzenschutzmittelrückstände im gehöselten Pollen der Honigbiene (Apis mellifera L.) : Auswirkungen einer feldrealistischen Pflanzenschutzmittelmischung auf Stockbienen und den Larvenfuttersaft
(2017) Böhme, Franziska; Zebitz, Claus P. W.
Pesticides are used worldwide and contaminate air, surfaces, soils and the aquifer. Non-target-organisms and non-target-plants may get into contact with pesticides di-rectly via drift or indirectly via run-off, leaching or sowing dust. Due to pollination services and bee products, the honeybee (Apis mellifera L.) is a non-target-organism of major interest for humans. On their flights around the beehive they collect water, pol-len, nectar, honeydew and tree resin. The proteins originating from the pollen are im-portant for nutrition and development of larvae and adults. Pollen is stored and fer-mented inside the hive as beebread and is made of hundreds of pollen loads of differ-ent plants collected over a longer period. Pesticide residue analyses of beebread is a common tool to estimate the contact of honeybees to pesticides in the field. However, such beebread analyses cover a larger time frame and a mixture with uncontaminated pollen will dilute the maximum residue levels of certain plant pollen. Therefore, pesti-cide analysis of bee bread is only an approximate approach to estimate the real pesti-cide exposition. Thus, pollen pellets were collected daily at three distinct sites with differences in agri-cultural intensity in Baden-Württemberg from 2012 - 2016 during the agronomic active season (spring/summer). We wanted to give detailed information on the daily contact to pesticides as well as changing pesticide frequencies and combinations throughout the season. 281 pollen pellet samples, each representing a single day, were analyzed for 282 active ingredients currently used in agricultural practice (publication 1). Huge qualitative and quantitative differences in the pesticide load between the sites were discovered. The meadow site near Göppingen was the least contaminated. In five ob-servation years only 24 different substances were found in 56 % of the samples with concentrations up to 300 µg/kg. The more intensive site in Ertingen is characterized by grains and maize for biogas plants. Only 13 % of the samples were uncontaminated, in the remaining samples 37 substances with maximal concentrations up to 1,500 µg/kg were detected. The site with the highest occurrence of crop protection was close to Heilbronn. Permanent crops such as wine and orchards shape the landscape. The high-est detected concentration was 7,178 µg/kg. All samples were contaminated with up to 58 different substances. During the five years of observation 73 different pesticides were found. Due to admis-sion regulations, there was a high likelihood to find 84 % of these substances in pollen. Twelve substances were found that are either not registered as plant protection prod-ucts or are not supposed to get in contact with bees. This indicates a need for further improvement of seed treatments and increasing awareness of flowering shrubs, field margins and pesticide drift. Concluding from the majority of concentrations and pesti-cides found, we assume no misuse of pesticides by the farmers at our three sites in the observation period, which would lead to direct intoxication. Considering LD50 values, the here detected concentrations are sub-lethal for honeybees. However, at any tested site and in most of the samples a mixture of different pesticides was found. Yet, it is not known, whether there are effects caused by a combination of different pesticides in sub-lethal concentrations when consumed chronically by honeybees. Therefore, we conducted a field experiment with free-flying honeybee colonies (publi-cation 2). Mini-hives containing about 2,500 bees and sister queens were established at the Apicultural State Institute. Queens were confined to an empty frame to receive lar-vae of known age. These bees were intended to feed on pesticides chronically in two crucial life stages. After larvae hatched from the eggs and after adults hatched from the cells they were fed a pollen-honey diet contaminated with a cocktail of twelve dif-ferent active ingredients in field-realistic concentrations. In colonies treated with a pes-ticide mixture, larval weight was higher and acini diameters of the hypopharyngeal glands of nurse bees were smaller than in the untreated control. However, brood termi-nation and adult lifespan did not differ between both groups. Despite feeding a pesti-cide cocktail chronically starting on the first day of larval being, no obvious negative side-effects in worker bees were detected. It raises the question, if nurse bees, which feed on the contaminated pollen-honey diet, produce larval food and feed larvae, serve as a filter system so that larvae would not come into contact with the pesticides. To determine the fate of pesticides originating from the pollen source, we started a queen rearing (publication 3). Frames with 24 h old larvae were hang into queenless free flying mini-hives. At the same time, the colo-nies were fed a pollen-honey diet containing a cocktail of 13 commonly used pesti-cides in high concentrations. The royal jelly (RJ) fed to the larvae by nurse bees was harvested from the queen cells and subjected to a multi-pesticide residue analysis. Sev-en substances were rediscovered in traces (76.5% of all detections were below 1 μg/kg). However, worker larvae older than three days receive a modified jelly, containing pol-len coloring the food yellowish. That is why we were wondering if contaminated pol-len might have a different effect on the food of worker larvae. Queens of free-flying mini hives were caged to receive larvae of known age. The colonies received a pollen-honey diet, contaminated with high concentrations of a pesticide mixture (publication 4, submitted). Worker jelly (WJ) was harvested on four successive days from larval age three to six and subjected to a multi-pesticide residue analysis. Pesticide concentrations increased with larval age and ranged between 2.9 and 871.0 µg/kg for the different substances and age groups. As the increase of substances in the WJ positively corre-lates with the amount of pollen grains counted in the larval food, we were able to show a direct relationship between the administered pollen in the food and the pesticide concentrations. Considering the maximum food uptake rates of a worker larvae, even the highest con-centrations found, would lead solely to sub-lethal amounts. Even for queens, who con-sume RJ not only as larvae but during their whole life would consume only sub-lethal pesticide concentrations. Especially considering the not-field realistic concentrations we chose for our experiments. Probably, the sub-lethal effects found in our first exper-iment are due to the sub-lethal concentrations worker larvae have taken up chronically during their development. Even though we did not detect acute intoxication symptoms and the concentrations in the brood food are sub-lethal, we cannot infer whether there are impairments of fitness or brood success of honeybee colonies in the long term. However, as honeybee colonies are considered as superorganisms, they are able to tol-erate stressors or the loss of individuals. Therefore, the detection of sub-lethal effects on colony-level in the field is difficult. Yet, a vast problem arises with solitary living insects, for example wild bee species, which are more prone to stressors such as pesti-cides. Solitary insects have more restricted flight and collecting areas, get into contact with pesticides in pollen directly as larvae and have almost no buffer capacities.