Die Praxis des Tötens von ca. 50 Millionen männlichen Eintagsküken aus Legelinen jedes Jahr in Deutschland steht seit einiger Zeit im Fokus gesellschaftlicher, ethischer und politischer Debatten. In der Landwirtschaft und ...

Root water uptake (RWU) is a key process in the root zone that determines water movement from the soil into roots and transport to the atmosphere via plant leaves. Different RWU models were developed with different assumptions ...

The aim of this work was to test strategies, which improve nutrient supply and weed control in occasional direct-seeded (DS) grain legumes in Organic Agriculture. The effect of intra-row fertilisation of rock phosphate (RP) and several sulphur fertilisers on crop growth, yield and nutrient uptake was studied in field trials with faba bean (Vicia faba) in Germany (two sites in NRW, 2011 and 2012) and with soybean (Glycine max) in Brazil (three sites in Paraná, 2012 and 2013). The second part of this work investigated weed control with natural herbicides (NH). Therefore, eighteen screening trials in the field and five field trials with soybean and common bean (Phaseolus vulgaris) were conducted in Brazil. Additionally, the effect of different amounts of oats straw residue on faba bean and weed shoot growth were examined as a second trial factor within the 2012 fertiliser trials in Germany. <br /> Soils at all <u>fertiliser trials</u> in Germany exhibited sufficient P-contents (LUFA C) and the intra-row<br /> fertilisation of RP (50 kg/ha^-1 P) did not have any effect on faba bean growth and P-uptake, neither alone nor in combination with elemental sulphur, which by way of in situ acid formation can enhance RP solubility. On the contrary, the sulphur fertilisers potassium sulphate, gypsum and elemental sulphur did result in a markedly increased S-uptake in both trial years, while faba bean growth and yield were only affected positively and in part significantly in the second trial year. The clear effect was assumed to be due to low soil sulphate contents during initial crop development, caused by low sulphate adsorption and hence high leaching rates during winter and also due to low soil organic matter (SOM) mineralisation rates under DS management. However in Brazil, soybean did not react to S-fertilisation with increased crop growth, yield or S-uptake in any trial. The sufficient S-supply was explained with the high contents of adsorbed sulphate in soil and high SOM mineralisation rates under tropical climate. P-fertiliser application was also ineffective at most sites due to sufficient to high soil P-contents. Only on a field with low P-contents at site Ponta Grossa P-fertilisation had a positive effect on P-uptake, crop growth and yield. In both years this positive effect was increased by simultaneous application of elemental sulphur, which presumably increased solubility of RP. <br /> In screening trials with <u>natural herbicides</u> pine oil and acidic acid were found to be the most potent active ingredients with a cell membrane disrupting (CMD) effect. While the sole spray application of high amounts of NaCl resulted in relatively weak plant damage, it was found that the combination of CMD and NaCl resulted in a strongly enhanced weed control. Additionally, a meristem damaging systemic effect of NaCl was identified, which was particularly strong for dicot weed species. In consequence, CMD amounts and hence application costs could be reduced drastically. Furthermore, it was determined repeatedly that emulsifiers influence formulation efficacy strongly at the rates commonly applied in NH and therefore these inert ingredients have to be considered as active ones in NH formulations. In the DS soybean field trial in Londrina it was determined that at a fixed total amount of AI (90 L/ha^-1 pine oil or limonene and 90 kg/ha^-1 NaCl) two concentrated applications resulted in a higher weed control than the three diluted ones. Weed control in this trial was not satisfactory, though, and crop growth as well as yield were markedly reduced compared to the clean control treatment. In the DS soybean trial<br /> in Ponta Grossa 50 L ha^-1 pine oil or limonene and 50 kg/ha^-1 NaCl were applied once, twice and three times. Even after three applications weed drymass remained relatively high compared to the weedy control. Nevertheless, soybean shoot drymass was not affected strongly by weed infestation and with three applications grain yield was close to the clean control. Nevertheless, results in this trial were influenced by crop damage due to contact with NH spray, because no working protective screen was available during application. In two field trials with conventionally tilled common bean, weed control was satisfactory in all spray treatments. Crop growth and yield were comparable to those of the weed free control....

Alluvial gold mining generates a vast amount of extractive waste that completely covers the natural soil, destroys riparian ecosystems, and negatively impacts river beds and valleys. Since 2002, a gold mining company has ...

In the rural and peri-urban settings, where agriculture is one of the main sources of livelihood, the multi-purpose character of irrigation and drainage infrastructure creates several interlinks between water, sanitation ...

Sustainable agriculture has become an important issue in the development-policy agenda in Sub-Saharan Africa (SSA), as a major avenue to simultaneously raise smallholder agricultural productivity and enhance climate change ...

Vitamin D deficiency and anemia are prevalent in patients with cardiovascular disease (CVD), and both are independent risk factors for increased morbidity and mortality. Epidemiological studies suggest an inverse association ...

This thesis examines the interlinkages between water quality, water use, sanitation and hygiene practices, other household characteristics and health outcomes in the context of multipurpose water systems in Ghana. ...

Liriomyza (Diptera: Agromyzidae) leafminers are pests of economic importance to the production of horticultural crops in East Africa. In the scope of a classical biological control program in East Africa, two parasitoids Halticoptera arduine (Walker) (Hymenoptera: Pteromalidae) and Chrysocharis flacilla Walker (Hymenoptera: Eulophidae) were introduced from Peru. This dissertation aims to assess the performance and impact of the parasitoids in biological control of Liriomyza leafminer species. Specifically, the research work aims to assess acceptability and suitability of the two parasitoids in three Liriomyza species, the potential interactions with a dominant local parasitoid, Diglyphus isaea (Walker) (Hymenoptera: Eulophidae), their establishment and spread after field release. In chapter two and three, performance data of the two exotic parasitoids in three Liriomyza leafminer flies are presented. Results show that the two parasitoids successfully accepted, parasitized, and completed their development in the three Liriomyza species in 15.97 ± 1.48 and 23.96 ± 0.88 d under controlled environments. Both parasitoids preferred to oviposit in L. huidobrensis (Blanchard) causing parasitism rates of between 27.96 ± 3.86 and 77.73 ± 4.39% across the hosts. Chrysocharis flacilla further induced significant non-reproductive pupal host mortality. Parasitoid F1 progenies were female-biased across the three hosts for C. flacilla except for a balanced sex ratio for H. arduine when reared on L. sativae Blanchard. Liriomyza huidobrensis yielded larger parasitoids and thus a good candidate for parasitoid mass rearing. <br /> In chapters four and five, the potential interactions between the two exotic parasitoids and the local parasitoid D. isaea were evaluated. Interaction results between H. arduine, C. flacilla, and D. isaea show perfect co-existence with no negative effect on performance of either of the parasitoids except on D. isaea's when C. flacilla came after D. isaea. Halticoptera arduine and C. flacilla had superior parasitism rates over D. isaea. Host parasitism rate more than doubled (53.27 ± 4.99 and 72.96 ± 4.12%) when each of the exotic parasitoids occurred together with D. isaea as opposed to when D. isaea acted alone. Both D. isaea and C. flacilla caused significant non-reproductive host mortality. Presence of H. arduine and C. flacilla positively affected D. isaea reproduction as only female parasitoids cause host suppression. <br /> In chapter six, results of parasitoid establishments and spread in three agro ecological systems are presented. Liriomyza huidobrensis is the dominant species across the three agro ecological systems. Further, a complex of 14 parasitoid species is associated with Liriomyza leafminers. Halticoptera arduine and C. flacilla are confirmed to have established during the survey period of between January 2013 and June 2014. There is an increased in pest suppression of up to 40%, with C. flacilla causing substantive specific field parasitism of 3.5%. Seasons, cropping systems and host plants affected parasitoid establishment. Halticoptera arduine moved 10 km away from the release point. <br /> Chapter seven discusses the implications of the findings in the management of Liriomyza leafminers. This work shows promising candidates as biological control agents against Liriomyza leafminers. This research will hopefully influence the private and public sector in the East African region to adopt sustainable pest management strategies that will conserve the parasitoids which might lead to a reduction in the (over) reliance on synthetic pesticide by small holder producers of horticultural crops....

Sensors can provide valuable insight into studying the physiological disorder due to plant pathogens. Fusarium head blight (FHB) influences the optical properties of wheat (Triticum aestivum L.) at canopy and ear levels. This research aimed to investigate these complex disease situations under field as well as controlled conditions with the application of proximal sensing systems.<br /> Observations under field conditions revealed that the presence of foliar diseases is associated with higher Fusarium infection in the wheat canopy (cv. Tobak and Pamier), which might be attributed to reduced defence mechanisms. This was reflected in increased FHB incidence visually assessed at growth stage (GS) 83. Fungicides applied against foliar diseases before anthesis reduced FHB presence, which might be not only due to reducing the available inoculum in the canopy but also due to promoting defenses against Fusarium infection. Furthermore, prediction of FHB through spectral parameters such as blue-green index 2 (BGI2) and photochemical reflection index (PRI) proved to be very promising.<br /> At ear level, development of Fusarium infection is dependent on the primary infection site within ears and the prevailing environmental conditions after infection. Such a relationship was verified under controlled conditions after tip, centre and base inoculations, separately, by F. graminearum and F. culmorum of wheat ears (cv. Passat). Symptom dynamics (FHB index) were slower downwards within ears in comparison to the upward development. In contrast to the symptom appearance the infection of Fusarium species proved to be directed basipetally – a rare development of fungal infections. According to these observations it could be revealed that higher temperatures accelerated the ripening of ears and allowed these plants to escape the infection within ears. In contrast, at lower temperatures, higher disease severity was observed even for tip infection.<br /> Infrared thermography could predict this primary site of ear infection through temperature span within ears and enabled disease detection before symptoms became visible. The temperature difference between air and ear was negatively correlated to FHB index and allowed disease detection at early senescence stage. Combining the features of thermal measurements and chlorophyll fluorescence images proved to present a high potential in characterising FHB at spikelet level. Discriminating spikelets infected with F. graminearum from those infected with F. culmorum were enabled up to 100% accuracy by fusion of sensor data.<br /> This study demonstrated that FHB is influenced by foliar wheat diseases when at low severities of both. The control of leaf pathogens by fungicides can play an important part in integrated disease management – also against Fusarium infections. It could also be confirmed that primary infection sites within ears and the prevailing environmental conditions after infection are key factors which determine the later development of FHB. Sensors proved to be useful in monitoring and assessing FHB under field conditions – detailed investigations under controlled conditions provided more profound insights in this regard. The findings of this research contribute to more efficient control of FHB using the concepts of remote sensing to improve precision plant protection and may be applied in selection processes of breeding for FHB resistance as well....
Geeignete Sensoren können einen wertvollen Einblick in die physiologischen Verhältnisse in Pflanzen bieten, wenn diese von pathogenen Organismen heimgesucht werden. Die Infektionen von Getreide durch Fusarium Arten (Fusarium Head Blight = FHB) verändern die optischen Eigenschaften von Wirtspflanzen – vor allem von Weizen (Triticum aestivum L.) – sowohl im Getreidestand als auch auf dem Niveau der einzelnen Ähren. Die vorliegenden Untersuchungen hatten zum Ziel, die näheren Gegebenheiten dieser komplexen Befallssituationen im Freiland und unter kontrollierten Bedingungen durch die Anwendung von zerstörungsfreien Messmethoden zu charakterisieren. <br /> Erhebungen im Feld machten deutlich, dass der Befall mit Fusarium Arten durch das Auftreten weiterer Blattkrankheiten im Weizenbestand gefördert wurde. Dies wurde beispielhaft an den Sorten „Tobak“ und „Pamier“ ermittelt und deutet auf eine geringere Widerstandsfähigkeit der Pflanzen gegenüber Fusariosen bei multiplem Befall hin. Dies konnte im Wachstumsstadium 83 (BBCH-Skala) auch makroskopisch festgestellt werden. Fungizidanwendungen, die vor der Blüte durchgeführt wurden, konnten das Auftreten der Fusarien am Weizen reduzieren. Dies war zweifellos auf die Reduktion des verfügbaren Inokulums der Fusarium-Arten zurückzuführen. Zugleich kann angenommen werden, dass durch die Gesunderhaltung der Blattfläche auch eine erhöhte Widerstandsfähigkeit der Pflanzen gegenüber Fusariosen hervorgerufen werden. Die Möglichkeit zur Vorhersage von FHB durch spektrale Parameter konnte bestätigt werden – vor allem an Hand des Blue- Green-Index 2 (BGI2) und des photochemischen Reflektionsindexes (PRI) erwiesen sich als besonders geeignet. <br /> An der Getreideähre ist die Entwicklung der Fusariosen in hohem Maße abhängig von dem primären Infektionsort und den nachfolgenden Umweltbedingungen im Anschluss an die Primärinfektion der Ähre. Dies konnte unter kontrollierten Bedingungen am Weizen der anfälligeren Sorte „Passat“ für Primärinokulationen an der an der Spitze, in der Mitte und an der Basis der Ähren nachgewiesen werden. Es zeigte sich, dass die Symptomentwicklung (FHB index) in der Ähre deutlich weniger nach unten gerichtet war, als in der Zone oberhalb des Inokulationspunktes. Dies galt sowohl für Infektionen durch F. graminearum als auch für F. culmorum. Im Gegensatz zur Symptomentwicklung entwickeln sich die Fusariosen vor allem abwärts in der Ähre – ein durchaus eher seltener Prozess für pflanzenpathogene Organismen. <br /> Erhöhte Temperaturen beschleunigen die Reifung der Ähren – obwohl günstig für das Auftreten von Fusariosen ermöglichen diese Bedingungen auch ein „disease escape“ gegenüber Fusarium-Arten. Bei niedrigeren Temperaturen führen die Infektionen zu deutlich höheren Infektionsraten, weil mehr Zeit zur Ausbreitung besteht – selbt in den Ährenspitzen. Mit Hilfe der Infrarot-Thermographie gelang es, die Primärinfektionen in der Ähre durch die Temperaturdifferenz zwischen Umwelt und den biologisch relevanten Zonen zu charakterisieren bevor bereits makroskopisch Symptome erkennbar wurden. Die Gewebetemperaturdifferenzen waren negativ korreliert mit dem FHB index – sie erlaubten aber auch eine Bestimmung des Reifestatus der Ähren. Wurden die Infrarotmessungen mit der Messung von Chlorophyllkorrelierten Messungen zerstörungsfrei kombiniert, lies sich damit eine hohe Korrelation identifizieren – insbesondere auf dem Niveau der einzelnen Ährchen. Wurden diese Beziehungen betrachtet, dann zeigte sich, dass sich sogar Unterschiede zwischen F. graminearum und F. culmorum erkennen ließen. <br /> Die vorliegenden Untersuchungen zeigen, dass das Auftreten von Fusariosen an Getreide auch in besonderem Umfang durch andere Blattkrankheiten gefördert wird – erkennbar allerdings nur bei geringen Befallsintensitäten. Die Förderung der Pflanzengesundheit – auch durch Fungizide – kann zu einer wichtigen Funktion im Integrierten Pflanzenschutz führen – sicher auch zum Schutz vor Ährenfusariosen. Es konnte nachgewiesen und durch Anwendung geeigneter Sensoren genutzt werden, dass die Fusarium-Infektionen eine besondere Rolle spielen. Vor allem die Primärinfektionsorte, die sehr umweltabhängig sind – haben großen Einfluss auf die Schadwirkung. <br /> Sensoren können offenbar sehr hilfreich bei dem Erkennen und der Befallsbestimmung – und das bereits unter Freilandbedingungen. Dies wurde durch Erhebungen unter Feldbedingungen bestätigt – ergänzt durch weitere Untersuchungen unter praktischen Bedingungen. Die vorliegenden Ergebnisse und Erkenntnisse können eine effizientere Unterdrückung von FHB ermöglichen. Dabei geht es darum, dass die Elemente des „sensing of diseases“ einerseits in den Integrierten Pflanzenschutz eingebunden werden können und zudem auch für Selektionsprozesse in der Züchtung zur Vermeidung von FHB genutzt werden kann....