Institut für Tropische Agrarwissenschaften (Hans-Ruthenberg-Institut)

Permanent URI for this collectionhttps://hohpublica.uni-hohenheim.de/handle/123456789/21

Browse

Now showing 1 - 20 of 200

Combining improved mungbean cultivars with plant growth promoting rhizobacteria inoculation and regulated deficit irrigation to increase crop productivity
(2024) Pataczek, Lisa; Cadisch, Georg
The cultivation of legumes provides an approach to sustainably intensify agricultural production, since short-duration legumes can fit into existing cereal-based cropping systems, diversifying farm incomes and farmers diets, as well as providing environmental benefits through the fixation of atmospheric N2 and, thus, enhancing yields of following crops. Mungbean is a legume, which plays already an important role in the traditional nutrition of people in the Global South. Its nutritious seeds can improve food security and the short growing duration facilitates the diversification of mainly cereal-based crop rotations. However, yields are low and may even become lower in future in the face of climate change. Main constraints of mungbean cultivation include pest and diseases, as well as heat, drought and soil salinity due to inappropriate irrigation techniques or saline ground water. The main aim of this thesis was therefore to analyse the effects of more advanced cultivation techniques, i.e. the use of plant growth promoting rhizobacteria (PGPR) and regulated deficit irrigation (RDI), on the productivity and nitrogen (N) fixation capacity of improved mungbean (Vigna radiata L.) cultivars, resistant and/or tolerant to pests, diseases, heat and soil salinity. An extended literature review was conducted to summarize the current understanding of the use of PGPRs and the effect on crop productivity, especially on marginal land (Chapter 2). The use of PGPRs can on the one hand side increase plant growth through direct and indirect mechanisms, such as BNF, hormone production and nutrient solubilization or the production of antibiotics to suppress phytodiseases. Especially 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity plays a significant role to reduce the negative impact of stress environments. On the other side PGPRs can be used to remediate decontaminated sites, through metabolic capabilities, transforming for instance aromatic compounds into less toxic compounds, or the biodegradation of pesticides and organic pollutants. Since ACC deaminase-producing bacteria are also supposed to enhance root growth, it is assumed that they can potentially increase soil N uptake and/or infection sites for rhizobia to biologically fix atmospheric N2 (BNF). In order to test the effect of ACC deaminase-producing PGPRs on mungbean productivity and N accumulation, three strains were tested as single- or multistrain inoculation in the field: Rhizobium phaseoli, Bacillus subtilis and Pseudomonas fluorescens (Chapter 3). Their effect on one improved mungbean cultivar (NM11, resistant to the Mungbean Yellow Mosaic Disease) was assessed on two research sites in Faisalabad, Pakistan. The impact of the strains differed significantly, with no effect on productivity (total biomass, seed yield) or total N accumulation (BNF and soil-N uptake) with multi-strain inoculation of all strains and single-strain inoculation of P. fluorescens. Inoculation with B. subtilis did, however, result in significantly increased dry matter (roots: +211 kg ha-1, total dry matter: +1.7 t ha-1), and total plant-N (+36 kg ha-1), while R. phaseoli inoculation enhanced BNF (+24%). The results suggested that only the single strain inoculation of B. subtilis and R. phaseoli was promising in terms of productivity increase, however, the choice of the strain should be made according to the soil-N status: low soil-N favors R. phaseoli inoculation, while medium to high soil-N would rather point towards the use of B. subtilis. The improved mungbean cultivar NM11 was additionally tested together with three other improved cultivars (AVMU 1604, AVMU 1635 and KPS2, resistant/tolerant to powdery mildew, bruchids and heat and salt, respectively), in combination with RDI in a greenhouse trial at the University of Hohenheim (Chapter 4). The aim was to identify differences in drought adaptation strategies between the cultivars in terms of dry matter partitioning, yield, harvest index, pod harvest index, water use efficiency and carbon-13 isotope discrimination. Levels of water deficit as depletion fractions (%) of total available soil water were set to 0.45, 0.65 and 0.8, corresponding to recommended irrigation, moderate and severe water deficit, respectively. The cultivars differed in their drought resistance strategies, exhibiting either drought escape, avoidance, tolerance or a combination of several strategies. The cultivar KPS2 showed mainly a drought escape mechanism through faster development, stable yields and greatest harvest index/pod harvest index (36%/69%) across all RDI treatments and cultivars. The cultivar AVMU 1604 displayed mainly a mixture of drought avoidance and escape through increased remobilization of assimilates from vegetative plant parts to pods/seeds, resulting in greater yield under water deficit by 52%. The choice of a cultivar for the field should be based, thus, on the prevailing climatic conditions (season and region): KPS2 can grow in areas with terminate drought conditions, whereas AVMU 1604 can tolerate intermittent drought conditions. The results of this thesis showed that ACC deaminase-producing PGPRs can substantially affect N uptake, although this effect is barely discussed in literature. Moreover, improved mungbean cultivars, exhibiting already a range of tolerances and resistances to certain pests and diseases, showed a great potential in adapting to drought conditions, representing a viable option for cultivation under increasing abiotic and biotic stress factors in the face of climate change.
Genetic relationships among resilience, fertility, and milk yield in dairy cattle performing in sub-Saharan Africa
(2025) Oloo, Richard Dooso; Chagunda, Mizeck G. G.
Despite the relevance of dairy production in the fight against food insecurity in sub-Saharan Africa (SSA), the negative effects of climate change and general changes in the production environment pose tremendous challenges to its profitability. Genetic improvement of resilience, the capacity of animals to be either minimally affected by an environmental disturbance or rapidly recover from a disturbance in their environment, is deemed as a part of the solution to low dairy productivity and poor cattle adaptability in SSA. However, to breed for resilience, reliable and practical methods for quantifying and analyzing resilience in SSA need to be described and undertaken. This thesis explored the measurement of resilience using different indicators and examined the relationships of resilience with fertility and milk production in dairy cows performing in SSA. Chapter two of this thesis reviewed potential solutions to enhance the sustainability and productivity of the dairy sector in SSA with an emphasis on breeding for resilience. It described the dairy production in SSA, and environmental challenges cattle have to weather in this region. The chapter further discussed different forms of resilience (general resilience and specialized resilience), indicators for measuring resilience, and provided insights into the data that can be utilized to quantify resilience in SSA’s dairy production systems. It is concluded that improving resilience of dairy animals in SSA would contribute to poverty alleviation, animal welfare improvement, and better preparedness in lieu of climate change in this region. In chapter three, the potential of quantifying general resilience using indicators based on deviations in milk yield was examined. Three indicators of general resilience were defined: variance (LnVar), lag-1 autocorrelation (rauto), and skewness (Skew) of deviations in milk yield based on actual and standardized deviations of observed milk yield from predicted milk yield. The heritability estimates of all resilience indicators except Skew were significant and ranged from 0.05 to 0.19. Weak to moderate genetic correlations were observed among indicators of general resilience, suggesting that these indicators captured different aspects of resilience. LnVar indicators indicated that resilient cows are genetically associated with better longevity. The use of actual deviations and standardized deviations to define indicators yielded identical traits except in LnVar. Standardization of deviations or correcting for the milk production potential of animals ensures that the resultant LnVar indicator does not inaccurately categorize low-producing animals as inherently resilient. The study concluded that LnVar holds a significant potential as a robust resilience indicator for dairy animals performing in SSA. The fourth chapter investigated the response of milk production at varying heat loads as an indication of heat tolerance, which is a specialized resilience. Random regression models, including reaction norm functions, were fitted to derive two resilience indicators: the slope of the reaction norm (Slope), and its absolute value (Absolute), reflecting changes in milk yield in response to varying heat load. Heritability estimates for these indicators ranged from 0.06 to 0.33 and were mostly significantly different from zero. The correlation analysis between these indicators and average milk yield revealed that high- producing cows are more vulnerable to heat stress and have less stable milk production under heat-stress conditions. The study demonstrated the possibility of using the slope of the reaction norm and its absolute value to measure the specialized resilience of dairy cattle to heat stress conditions in SSA. Chapter 5 examined the genetic parameters and relationships among resilience, fertility, and milk production traits. The heritability estimates of age at first calving (AFC), calving interval (CI), and test-day milk yield (MY) were 0.17, 0.06, and 0.35 respectively, and were all significantly different from zero. AFC was negatively correlated with both CI and MY, showing that animals that attain sexual maturity earlier exhibit longer calving intervals and higher milk production. A positive correlation between CI and MY showed that high-yielding cows faced challenges in maintaining shorter calving intervals. There was a generally positive correlation between resilience and fertility, implying that resilient animals might have better fertility. All indicators, except the variance of actual deviation corrected for milk production and variance of standardized deviations, revealed an antagonistic relationship between resilience and milk production. This thesis showed the potential for quantifying and breeding for resilience in dairy cattle performing in SSA. Cows with more than 50% Zebu genes and those performing in semi-arid environments had higher resilience, higher AFC, shorter CI, and lower MY. This suggests that zebu genes confer resilience advantage to animals and exposure of animals to various disturbances in semi-arid environments improved their resilience capacity. Different directions of relationship observed among the traits studied imply that developing a multi-trait selection index that combines all these traits could strike the right balance among resilience, fertility, and milk production. The implications of these findings are valuable in improving the productivity of dairy cattle through selective breeding for resilience to environmental stressors, particularly in low-income countries situated in tropical regions.
Genetics and breeding for humoral immunity and feed efficiency in indigenous chicken population in Kenya
(2024) Miyumo, Sophie; Chagunda, Mizeck G. G.
Indigenous chicken (IC) population contribute to food, nutrition, livelihood and economic security in many rural households in developing countries in the tropical regions. Despite their contribution, IC are predominantly raised under challenging free-range systems which limit their optimal production potential and utilization. Of significance, are disease morbidity and scarcity of feed resources. Indigenous chicken are exposed to a myriad of pathogens that cause various poultry diseases which result to massive production and economic losses. Among these diseases is Newcastle disease (NCD) which is endemic in the tropics and is considered important because of high prevalence and mortality rates. Seasonal variation in availability and quality of feed resources have a negative impact on production costs and performance of chicken. Furthermore, with climate change effects, environmental conditions are expected to significantly impact feed availability and pathogen epidemiology. Selective breeding for disease resistance and feed efficiency traits is an avenue through which individuals that are adaptative to disease-prone production environments, with ability to efficiently convert available feed resources into products and support their maintenance requirements can be sustainably produced. Therefore, this thesis aimed to generate information that can guide breeding decisions on selection for improved health and efficient production to enhance the overall performance of the indigenous chicken population in Kenya. Chapter 1 presented an overview on the relevance of indigenous chicken genetic resources in developing countries with respect to their proportion among chicken population, contribution at household and national levels, and adaptive capacity to local environments. The challenges experienced in IC production systems in developing countries and their impacts on productivity and profitability, with a focus on diseases and scarcity in feed resources were addressed in this chapter. Management strategies practiced on-farm to control diseases and cope with seasonal availability of feed resources and the limitations of these strategies were also discussed. Proposed alternative strategies related to selective breeding for traits that can be utilized to manage diseases and scarcity in feed resources in IC production systems were presented in this chapter. Finally, the chapter gave a justification for this study, and objective and outline of the thesis. Literature estimates of genetic parameters are considered resourceful in instances where estimates for traits of interest are not available or insufficient. Estimates obtained from different studies, however, may vary due to differences in population among other factors. The choice of which estimate from sampled studies to use, is in most cases subjective and this may lead to either underestimation or overestimation of potential genetic progress. Chapter 2 assessed the robustness of literature estimates of genetic parameters for traits of economic importance in chicken performing in the tropical and sub-tropical environments using meta-analysis. Additive genetic, maternal environment and residual variances, and heritability estimates for traits related to immunity, reproduction, survival, growth, egg production and feed efficiency from 70 studies were considered. Heterogeneity index showed that published estimates of the genetic parameters sampled from different studies significantly varied in each of the traits. Based on total variance, a higher proportion of the variation in genetic parameters were more due to random effect of study than sampling error. Reliability estimates (relative standard error) of the genetic parameters varied across the traits considered in this study, in which, traits well represented in terms of number of published estimated had lower levels of variation compared to traits with low published estimated. Study characteristics related to population, production system, estimation methods, sex, age and antigen (only for immune traits) significantly influenced variation in the sampled genetic parameters across the traits. Pooled genetic parameters estimated in this study using the inverse of sampling variance as a weighting factor indicate that the weighted averages of genetic parameters can be utilized where estimates are not available or insufficient. The significant variation among sampled studies and low reliability estimated in some of the traits imply that genetic parameter estimates from literature should be applied with caution to prevent negative impacts on breeding decisions and genetic progress. In addition, differences in study characteristics should be considered in order to use estimates from studies with population and production conditions characteristics that closely resemble the intended population and production system. Antibody response to challenging conditions is suggested a suitable indicator trait that can be utilized for indirect improvement of disease resistance. However, prior to selection, understanding the genetic background of antibody response in the population of interest is a prerequisite in setting up an effective selection strategy. Chapter 3 investigated non-genetic and genetic sources of variation in natural antibodies binding to keyhole limpet hemocyanin antigen (KLH-NAbs) and specific antibodies binding to NCD virus (NDV-IgG). Non-genetic factors related to sex, population, phylogenetic cluster, generation, line, genotype and age significantly influenced the antibody traits, and should therefore be accounted for in genetic evaluations to reduce bias and improve accuracy of selection. Considerable amount of additive genetic variation was observed in the KLH-NAbs and NDV-IgG traits, implying possibilities of improvement of the antibody traits through selective breeding. However, the low to moderate heritability estimated in the antibody traits indicate that relatively low accuracy levels would be expected and hence, reduced rate of genetic gains if mass selection would be used. Positive genetic correlations observed among KLH-NAb isotypes (KLH-IgM, KLH-IgG and KLH-IgA) suggest that the isotypes can be improved simultaneously. In contrast, KLH-NAbs were negatively correlated with NDV-IgG implying that genetic improvement of natural antibodies would be associated with low specific antibodies binding NDV. These findings provide a better understanding of factors affecting antibody traits in a heterogeneous chicken population and may enable effective decisions prior to inclusion of immune parameters in breeding programs intended for tropically adapted chicken. Considering that an effective immune system is heavily dependent on metabolic resources for maintenance and deployment of various immune responses, improved antibody levels is expected to compete for nutrients and energy with other functions, such as production. Besides, given the scarcity in feed resources in production systems in Kenya, competition for nutrients and energy among biological functions is likely to influence the efficiency of feed utilization. Therefore, it is pertinent to also determine the pleiotropic nature between the immunity, production and feed efficiency traits. Chapter 4 estimated genetic and phenotypic correlations among antibody, feed efficiency and production traits measured pre- (nine to 20 weeks of age) and post- (12 weeks from on-set of lay) maturity. Results revealed that improved feed efficiency would be associated with high growth rates, early maturing chicken, high egg mass and reduced feed intake. In contrast, improved general (KLH-IgM) and specific (NDV-IgG) immunity would result in lower growth rates and egg mass but associated with early sexual maturation and high feed intake. Negative genetic correlations estimated between feed efficiency and antibody traits imply that chicken of higher productivity and antibody levels will consume more feed to support both functions. These associations indicate that selective breeding for feed efficiency and immune competence may have genetic consequences on production traits and should therefore be accounted for in IC improvement programs. Based on marketable end products, a breeding goal targeting simultaneous improvement of meat and egg production to develop a dual-purpose (ICD) breed that can perform in low to medium input systems is recommended for the IC population. However, due to the dynamics in market forces over time, goals targeting specialized production to develop a meat (ICM) and a layer (ICL) breed that can perform in medium to high input systems are also recommended as alternatives. Prior to defining the selection criteria across the goals, it is necessary to determine optimal combination of traits in an index because this has an impact on the overall genetic merit of an individual and total index response. Chapter 5 evaluated various selection strategies for adoption in ICD and ICL and ICM goals in indigenous chicken breeding with respect to total index response, accuracy of selection, rate of inbreeding and number of generations of selection required to achieve pre-defined genetic gains. Selection strategy targeting only production traits in a goal had the highest total index response, highest index accuracy (only ICM goal) and lowest inbreeding rate per generation, and least number of generations of selection required to achieve pre-defined gains. The index was, however, associated with unfavorable correlated responses in feed efficiency and antibody traits. Addition of both feed efficiency and antibody response in a goal indicated favorable genetic gains could be achieved in these traits. Conversely, this strategy reduced total index response and increased the rate of inbreeding per generation and required additional number of generations of selection to achieve desired gains pre-defined in each of the goals. Inclusion of either feed-related traits or antibody traits in a goal showed that feed-related traits had a more negative impact on the total index response per generation but improved selection accuracy in the ICD and ICL goals compared to antibody traits. Based on these results, choice of whether to include feed efficiency or/and antibody response in the ICD, ICM and ICL goals should depend on targeted production system, resource availability to support additional number of generations of selection and magnitude of correlated responses on these traits when not included in the goals. Lastly, a synthesis of the thesis is presented in Chapter 6 where practical relevance and utilization of findings of the thesis in designing a breeding program for indigenous chicken population is demonstrated.
Etablierung und Vernetzung digital-gestützter Systeme auf Pferdebetrieben unter Berücksichtigung der betriebswirtschaftlichen Optimierung
(2024) Speidel, Linda Thurid; Dickhöfer, Uta
Das Management eines pferdehaltenden Betriebs umfasst eine Vielzahl arbeitswirtschaftlicher Herausforderungen. Dazu zählen unter anderem die zeitintensiven Arbeitsabläufe, das notwendige Kundenmanagement in Pensions- und Schulpferdebetrieben sowie die begrenzte Verfügbarkeit von Fachkräften. Auf Ackerbau- und Veredelungsbetrieben wird der Nutzen der Digitalisierung bereits wahrgenommen, da deren Einsatz unter anderem Potenzial zur Zeitersparnis und Arbeitserleichterung bietet. Obgleich des genannten Potenzials sind Pferdebetriebe bisher wenig digitalisiert und technisiert, die Grundversorgung erfolgt meist manuell. Im Rahmen dieser, im Projekt „Digitale Wertschöpfungsketten für eine nachhaltige kleinstrukturiert Landwirtschaft“ (DiWenkLa) angefertigten, Forschungsarbeit wurde daher untersucht, welche Möglichkeiten der Digitalisierung bisher genutzt werden und unter welchen Voraussetzungen die einzelnen Systeme in Pferdebetrieben etabliert werden können. Des Weiteren wurde analysiert, welche Auswirkungen der Einsatz dieser Systeme auf den Arbeitszeitbedarf im Pferdebetrieb hat und welche Informationen über Schnittstellen zwischen den Systemen ausgetauscht werden können. Dafür wurden von März 2020 bis Oktober 2023 Experteninterviews, (Arbeitszeit-)Beobachtungen und Online-Befragungen durchgeführt. Zunächst wurden die vorhandenen Möglichkeiten der digitalen Technisierung auf Pferdebetrieben in der Fütterung von Rau- und Krippenfutter, der Entmistung und Einstreu, der Gesundheits- und Sicherheitsüberwachung sowie der Kommunikation und dem Betriebsmanagement untersucht. Der Schwerpunkt lag auf den Voraussetzungen, die erfüllt sein müssen, um ausgewählte digital-technische Systeme auf den Betrieben zu etablieren. Zu diesem Zweck wurden Beobachtungen und Befragungen bei pferdehaltenden Betrieben (N=1235) und den Kooperationspartnern aus der Industrie des Projekts DiWenkLa durchgeführt. Die Ergebnisse zeigen, dass die Einbindung digital-technischer Systeme von der Investitionsbereitschaft der Betriebsleitenden, der stabilen Internetverbindung, einer verfügbaren Stromversorgung in den Stallgebäuden (Steckdosen) und dem vorhandenen Haltungssystem (z. B. Einzel- oder Gruppenhaltung sowie Gliederung der Haltung in Funktionsbereiche) abhängt. Auf den an einer Online-Befragung teilnehmenden Pferdebetrieben (N=451) wurden Kameras zur Sicherheits- (30,8 %) und Gesundheitsüberwachung (22,6 %) sowie Software für die Kundenkommunikation (24,8 %) und das Betriebsmanagement (13,7 %) eingesetzt. Die automatisierte Fütterung von Krippenfutter (9,3 %) und Raufutter (7,3 %) war selten vorhanden. Eine Gliederung der Haltung in Funktionsbereiche führte zu einem vermehrten Einsatz digital-technischer Systeme. Als Gründe gegen den Einsatz neuer digital-technischer Systeme wurden von den 207 teilnehmenden Betriebsleitenden die fehlenden Finanzmittel, der unbekannte wirtschaftliche Nutzen sowie der Kontaktverlust zu den Tieren genannt. In Anlehnung an die vorliegenden Ergebnisse erscheint eine erneute Erhebung der vorhandenen Systeme auf Pferdebetrieben sinnvoll, um etwaige Veränderungen im Verlauf der Zeit abzubilden und die Gründe für die Investition in neue digital-technische Systeme zu ermitteln. Des Weiteren sollte untersucht werden, ob Einsteller bei einem höheren Digitalisierungsgrad im Pferdebetrieb bereit sind, einen höheren Pensionspreis zu bezahlen. Zu diesem Zweck könnte die Zahlungsbereitschaft beim Einsatz von z. B. Futterautomation und intelligenten Kameras zur Gesundheitsüberwachung abgefragt werden. Des Weiteren wurde analysiert, welche betriebswirtschaftlichen Vorteile die auf den Pferdebetrieben etablierten, digital gesteuerten Systeme mit sich bringen können. Dazu wurden die möglichen Auswirkungen der Digitalisierung auf den Arbeitszeitbedarf für verschiedene Arbeitsabläufe wie die Fütterung, Entmistung und Hütesicherheit untersucht. Dies wurde durch Zeiterfassungen mit und ohne den Einsatz der Systeme sowie mit Hilfe von Online-Befragungen (N=1014) und Experteninterviews (N=16) realisiert. Die Ergebnisse der Untersuchungen zeigen bei der Einzelhaltung von Pferden eine potenzielle Arbeitszeitersparnis in der Fütterung und Entmistung von bis zu 65 % durch eine automatisierte Fütterung von Rau- und Krippenfutter und den Einsatz von mobiler Technik, wie beispielsweise einem Hoflader. Zudem kann der Einsatz dieser Systeme auch dazu führen, dass die benötigte Arbeitszeit in anderen Arbeitsabläufen sinkt. Ein Beispiel hierfür ist der Einsatz einer automatisierten Fütterung, welcher zu einer geringeren Arbeitszeit in der Kundenkommunikation führte. Dies wurde in den durchgeführten Datenerhebungen dadurch begründet, dass gewünschte Änderungen in der Rationsgestaltung automatisiert erfolgen und somit nicht persönlich kommuniziert werden müssen. Darüber hinaus lassen sich durch eine digitale Absprache und die Dokumentation wesentlicher Arbeitsschritte und Änderungen in den Abläufen sowie Kundenwünschen Fehler reduzieren und Missverständnisse vermeiden. Auf Basis der Ergebnisse sollten die Abfragen der Arbeitszeitbedarfe der Arbeitsabläufe mit exakten und vorgegebenen Werten wiederholt und teilweise ergänzt werden. Dies betrifft z. B. den Zeitbedarf für das Betriebsmanagement, die Tierkontrolle und den Weidegang. Dadurch können die vorhandenen Kalkulationsgrundlagen aktualisiert und das Bewusstsein der Betriebsleitenden für teils unbeachteten Arbeitszeitaufwand geschärft werden. Dieser kann wiederum durch den Einsatz von digital-technischen Systemen reduziert werden. Darüber hinaus wurde ein Konzept für eine Schnittstelle für digitale Systeme für Pferdebetriebe entwickelt, um den Datenaustausch zwischen Systemen zu vereinfachen und somit die Übersichtlichkeit der verschiedenen Informationen aus den eingesetzten Technologien zu optimieren sowie zusätzliche Zeitersparnis zu gewährleisten. Dazu wurden mittels Experteninterviews (N=20 Experten) die auszutauschenden Informationen zwischen Systemen für die Fütterung, die Entmistung und Einstreu, die Gesundheits- und Sicherheitsüberwachung sowie das Betriebsmanagement und die Kommunikation identifiziert, um eine verbesserte Übersicht für die Betriebsleitenden zu gewährleisten. In diesem Kontext wurde der Datenaustausch zwischen Futterautomationen und Kommunikationssoftware als besonders relevant hervorgehoben. Je nach Bedarf können die Informationen aus dem Datenaustausch transparent an die Kunden (z. B. Einsteller) weitergegeben werden. Eine Online-Befragung ergab, dass die Mehrheit (57,2 %) aller Teilnehmenden (N=451) Interesse an einer Vernetzung der Systeme zeigt. In zukünftigen Untersuchungen könnten zum einen die Gründe für das Interesse an einer Vernetzung analysiert werden, da bisher lediglich die Gegenposition untersucht wurde (d.h. Gründe gegen das Interesse an der Vernetzung). Zum anderen könnte die Einbindung weiterer Systeme neben den genannten geprüft werden, insbesondere die Anbindung der vorhandenen Hardware (z. B. Solarien, Aquatrainer) an das Internet und die (standardisierte) Programmierung der Schnittstelle, um z. B. eine unkomplizierte und transparente Abrechnung der Nutzung zu ermöglichen. Die Etablierung und Vernetzung digital-technischer Systeme in Pferdebetrieben ist bei erfüllbaren Voraussetzungen als sinnvoll anzusehen, da sie eine Arbeitszeiteinsparung generieren, eine Entlastung der Arbeitskräfte ermöglichen, die Kommunikation verbessern und das Betriebsmanagement sowie die Sicherheits- und Gesundheitskontrolle der Tiere vereinfachen. Diese Faktoren sind neben der Beachtung und Verbesserung des Tierwohls für eine nachhaltige, zukunftsfähige Pferdehaltung unabdingbar.
Rumen fermentation, microbial protein synthesis, and nitrogen balance in tropical cattle fed cultivated forages
(2024) Sainz-Sanchez, Pedro Alan; Dickhöfer, Uta
Over the past decade, extensive research has focused on the role of cultivated forages in cattle diets and their effects on animal performance, particularly in terms of milk yield and daily live weight gain. Despite this progress, there remains a scarcity of information regarding the dietary factors influencing the efficiency of ruminal microbial crude protein (MCP) synthesis and nitrogen (N) balance in tropical cattle fed on cultivated forages. In the Tropics and Subtropics, a variety of non-structural carbohydrate (NSC) sources are commonly used as energy supplements for tropical cattle. Current advancements in ruminant nutrition highlight the need for a deeper understanding of the complex interactions between the type of NSC, the kinetics of starch degradation, and the timing of supplementation, particularly in the context of high-quality forage diets. Hence, the overall objective of the thesis was to comprehensively understand the dietary factors influencing the rumen MCP synthesis and N balance in tropical cattle fed on high-quality and low-quality cultivated forages. This doctoral thesis hypothesized that the rumen MCP synthesis and the N balance in tropical cattle are mainly affected by the crude protein (CP) and fiber concentrations of cultivated forages. It was further hypothesized that dietary factors such as the supplementation of NSC, type of NSC, and time of supplementation influence the nutritional quality of cultivated forages and affect the rumen MCP synthesis and excretion in tropical cattle. Overall, one in vitro and two in vivo studies were conducted to investigate the proposed hypotheses. In the first in vivo study (Chapter 2), three forage grass species (Cenchrus purpureus, Chloris gayana, and Urochloa brizantha), grown alone or intercropped with a forage legume (Dolichos lablab), were evaluated to determine feed intake, digesta passage rates, rumen MCP synthesis, and N balance in Boran steers. The results showed similar duodenal MCP flow, MCP synthesis efficiency, and digesta passage rates in steers fed different forage grasses, whether grown alone or intercropped. Minor variations in dry matter (DM) intake largely drove increased N intake, fecal N excretion, and N balance, particularly when no significant differences in the chemical composition of the forage grass species were observed. The in vitro study (Chapter 3) evaluated the interactions between tropical forage grasses (Urochloa humidicola and Urochloa mutica) and forage legumes (Desmodium uncinatum, Stylosanthes guianensis, and Mucuna pruriens) and their effects on in vitro total gas production (TGP), short-chain fatty acids (SCFA) concentration and profile, and MCP synthesis. For this, various forage-legume mixtures were prepared by varying the ratios of forage legume to forage grass (75:25 or 25:75 on DM basis). Results indicated that in vitro TGP, short-chain fatty acids concentration and profile, and MCP synthesis were influenced by CP concentration, CP degradation extent, and the fermentation of both structural and NSC of the forages. Additionally, supplemental CP and NSC, influenced in vitro TGP and MCP synthesis. The second in vivo study (Chapter 4) evaluated the use of corn and oat, differing in extent and rate of ruminal starch degradation as NSC sources (i.e., corn- and oat-based concentrate mixtures), supplemented to lactating Brown Swiss cows before or after grazing on an alfalfa-ryegrass sward. The study measured feed intake, rumen MCP synthesis, nutrient digestibility, N partitioning, and milk performance. Supplementing corn-based concentrate mixture after grazing and oat-based concentrate mixture before grazing improved the efficiency of MCP synthesis, milk performance, and efficiency of N use in grazing lactating dairy cows. The effects of NSC supplementation were influenced by the interdependent interactions of starch concentrations of NSC sources, their ruminal degradation kinetics, and the timing of supplementation. The findings of the present thesis, supported by existing literature, demonstrate that cultivated tropical forages can provide sufficient N compounds to support rumen MCP synthesis, meeting the CP requirements of tropical cattle without negatively affecting DM intake, nutrient digestibility, N balance, or overall animal performance. Although CP concentration of the cultivated forages is a key factor influencing rumen MCP synthesis and N balance in tropical cattle, this perspective overlooks important aspects such as the distinction between rumen degraded protein and rumen undegraded protein which provide a clearer representation of CP degradation and utilization at both, the ruminal and post-ruminal levels. The CP concentration in cultivated tropical forages is not the only factor affecting N balance; other nutritional factors, such as energy concentration, neutral detergent fiber, and acid detergent fiber concentrations, also play a crucial role. Specifically, the energy concentration of the forage affects the capture of N by ruminal microbes, while the concentrations of neutral detergent fiber and acid detergent fiber influence the available energy in the forage, thereby impacting overall N utilization in tropical cattle. The interaction between the time of supplementation and the type of NSC source influences the synchronization of N and energy in the rumen. The response to NSC supplementation is influenced by the timing of supplementation and the degradation rates of CP and carbohydrates in both the forages and NSC sources. In the context of the results presented in the present thesis and the existing literature, cultivated tropical forages not only enhance protein nutrition and performance in tropical cattle but may also contribute positively to environmental sustainability. For instance, reducing urinary and fecal N excretion helps limit excessive N release into the environment. Additionally, intercropping forage legumes with grasses can enhance soil fertility and improve soil structure. However, further research is required to assess overall system sustainability and to develop comprehensive feeding strategies for tropical cattle in the Tropics and Subtropics.
Relationship between nutritional composition and fibre digestibility in tropical forages compared to temperate forages
(2024) Nurdianti, Risma Rizkia; Dickhöfer, Uta; Castro-Montoya, Joaquín Miguel
The study aimed to analyse variability in nutrient concentration and fibre digestibility in forage legumes and grasses from tropical and temperate regions and identify forage species with similar fibre concentration and digestibility. Forty-five samples comprised 22 tropical forage legumes, four temperate forage legumes, eleven tropical grasses, and eight temperate grasses were analysed for their proximate nutritional composition, as well as fibre digestibility by 240-h of in vitro incubation in buffered rumen fluid. All data were analysed using SAS (SAS Institute Inc., USA). Pearson correlations and multiple linear regressions were determined using CORR and GLM procedures, respectively. Cluster analyses were done using CLUSTER procedures. Tropical forage legumes had greater ash-corrected neutral detergent fibre (aNDFom) concentrations compared to temperate forage legumes, but lower aNDFom concentrations compared to tropical and temperate grasses. Tropical forage legumes had greater undigested neutral detergent fibre estimated after 240 h in vitro incubation (uNDF240) concentrations compared to other forages. In tropical forage legumes, aNDFom and lignin concentrations correlated with uNDF240 concentration (p < 0.001). Meanwhile, there were no relationships between explanatory variables and fibre digestibility (p > 0.100). Four clusters of forage species varying in fibre concentration and fibre digestibility were identified. Peanut, lima bean, and cowpea forages might have low fibre concentration and medium fibre digestibility similar to those of alfalfa and red clover. Despite differences in environmental conditions, tropical forage legumes might compete with temperate species in terms of nutrient and fibre quality. This information allows tropical farmers to improve forage quality by choosing appropriate species.
Metabolome fingerprinting reveals the presence of multiple nitrification inhibitors in biomass and root exudates of Thinopyrum intermedium
(2024) Issifu, Sulemana; Acharya, Prashamsha; Schöne, Jochen; Kaur-Bhambra, Jasmeet; Gubry-Rangin, Cecile; Rasche, Frank
Biological Nitrification Inhibition (BNI) encompasses primarily NH4 +-induced release of secondary metabolites to impede the rhizospheric nitrifying microbes from per- forming nitrification. The intermediate wheatgrass Thinopyrum intermedium (Kernza®) is known for exuding several nitrification inhibition traits, but its BNI potential has not yet been identified. We hypothesized Kernza® to evince BNI potential through the presence and release of multiple BNI metabolites. The presence of BNI metabolites in the biomass of Kernza® and annual winter wheat (Triticum aestivum) and in the root exudates of hydroponically grown Kernza®, were fingerprinted using HPLC-DAD and GC–MS/MS analyses. Growth bioassays involving ammonia-oxidizing bacteria (AOB) and archaea (AOA) strains were conducted to assess the influence of the crude root metabolome of Kernza® and selected metabolites on nitrification. In most instances, significant concentrations of various metabolites with BNI potential were observed in the leaf and root biomass of Kernza® compared to annual winter wheat. Furthermore, NH4 + nutrition triggered the exudation of various phenolic BNI metabolites. Crude root exudates of Kernza® inhibited multiple AOB strains and completely inhibited N. viennensis. Vanillic acid, caffeic acid, vanillin, and phenylalanine suppressed the growth of all AOB and AOA strains tested, and reduced soil nitrification, while syringic acid and 2,6-dihydroxybenzoic acid were ineffective. We demonstrated the considerable role of the Kernza® metabolome in suppressing nitrification through active exudation of multiple nitrification inhibitors.
Biomonitoring via DNA metabarcoding and light microscopy of bee pollen in rainforest transformation landscapes of Sumatra
(2022) Carneiro de Melo Moura, Carina; Setyaningsih, Christina A.; Li, Kevin; Merk, Miryam Sarah; Schulze, Sonja; Raffiudin, Rika; Grass, Ingo; Behling, Hermann; Tscharntke, Teja; Westphal, Catrin; Gailing, Oliver; Carneiro de Melo Moura, Carina; Department of Forest Genetics and Forest Tree Breeding, University of Göttingen, Göttingen, Germany; Setyaningsih, Christina A.; Department of Palynology and Climate Dynamics, Albrecht-von-Haller-Institute for Plant Sciences, University of Göttingen, Göttingen, Germany; Li, Kevin; Agroecology, Department of Crop Sciences, University of Göttingen, Göttingen, Germany; Merk, Miryam Sarah; Statistics and Econometrics, University of Göttingen, Göttingen, Germany; Schulze, Sonja; Agroecology, Department of Crop Sciences, University of Göttingen, Göttingen, Germany; Raffiudin, Rika; Department of Biology, IPB University ID, Bogor, Indonesia; Grass, Ingo; Department of Ecology of Tropical Agricultural Systems, University of Hohenheim, Stuttgart, Germany; Behling, Hermann; Department of Palynology and Climate Dynamics, Albrecht-von-Haller-Institute for Plant Sciences, University of Göttingen, Göttingen, Germany; Tscharntke, Teja; Agroecology, Department of Crop Sciences, University of Göttingen, Göttingen, Germany; Westphal, Catrin; Functional Agrobiodiversity, Department of Crop Sciences, University of Göttingen, Göttingen, Germany; Gailing, Oliver; Centre of Biodiversity and Sustainable Land Use, University of Göttingen, Göttingen, Germany
Background: Intense conversion of tropical forests into agricultural systems contributes to habitat loss and the decline of ecosystem functions. Plant-pollinator interactions buffer the process of forest fragmentation, ensuring gene flow across isolated patches of forests by pollen transfer. In this study, we identified the composition of pollen grains stored in pot-pollen of stingless bees, Tetragonula laeviceps , via dual-locus DNA metabarcoding (ITS2 and rbcL ) and light microscopy, and compared the taxonomic coverage of pollen sampled in distinct land-use systems categorized in four levels of management intensity (forest, shrub, rubber, and oil palm) for landscape characterization. Results: Plant composition differed significantly between DNA metabarcoding and light microscopy. The overlap in the plant families identified via light microscopy and DNA metabarcoding techniques was low and ranged from 22.6 to 27.8%. Taxonomic assignments showed a dominance of pollen from bee-pollinated plants, including oil-bearing crops such as the introduced species Elaeis guineensis (Arecaceae) as one of the predominant taxa in the pollen samples across all four land-use types. Native plant families Moraceae, Euphorbiaceae, and Cannabaceae appeared in high proportion in the analyzed pollen material. One-way ANOVA (p > 0.05), PERMANOVA (R² values range from 0.14003 to 0.17684, for all tests p-value > 0.5), and NMDS (stress values ranging from 0.1515 to 0.1859) indicated a lack of differentiation between the species composition and diversity of pollen type in the four distinct land-use types, supporting the influx of pollen from adjacent areas. Conclusions: Stingless bees collected pollen from a variety of agricultural crops, weeds, and wild plants. Plant composition detected at the family level from the pollen samples likely reflects the plant composition at the landscape level rather than the plot level. In our study, the plant diversity in pollen from colonies installed in land-use systems with distinct levels of forest transformation was highly homogeneous, reflecting a large influx of pollen transported by stingless bees through distinct land-use types. Dual-locus approach applied in metabarcoding studies and visual pollen identification showed great differences in the detection of the plant community, therefore a combination of both methods is recommended for performing biodiversity assessments via pollen identification.
Insect conservation in agricultural landscapes needs both high crop heterogeneity and semi-natural habitats
(2024) Tassoni, Sara; Becker, David; Kasten, Marit Kinga; Moriníere, Jérôme; Grass, Ingo
Identifying landscapes that are suitable for both biodiversity conservation and agricultural production is a major challenge. Traditionally, much research has focused on biodiversity conservation outside of agricultural production areas, e.g., in semi-natural habitats. In contrast, recent research has mainly focused on the potential of crop heterogeneity. This includes both compositional (crop diversity) and configurational heterogeneity (field border density). However, if and how crop heterogeneity, and semi-natural habitats interact to shape insect diversity in agricultural landscapes remains poorly understood. Here we investigated the combined effects of crop diversity, field border density, and semi-natural habitats (i.e., grassland proportion, hedge density) on insect diversity. We sampled insect communities from 14 – 17 June 2021 with pan traps in 27 study landscapes (500 m x 500 m) covering independent gradients of these landscape variables and identified a total of 587 insect species with DNA metabarcoding. We found that field border density mediated the effects of crop diversity, grassland proportion, and hedge density on insect richness. At low levels of field border density (i.e., landscapes with mostly large fields), effects were either neutral (crop diversity), negative (grassland proportion) or weakly positive (hedge density). By contrast, at high levels of field border density, crop diversity, grassland proportion, and hedge density all exerted positive effects on insect richness. Responses to crop heterogeneity and semi-natural habitat differed among trophic groups of insects (decomposers, herbivores, parasitoids, predators). While variation in richness of herbivorous insects followed the patterns of the overall richness, decomposer richness was not related to any of the investigated variables. Predator richness increased with hedge density in landscapes, whereas parasitoid richness increased when high levels of field border density and grassland proportion coincided. Our study shows that increasing crop heterogeneity is a viable strategy for promoting insect diversity in agricultural landscapes. However, the effects of the amount of remaining semi-natural habitats, such as grassland or hedges, are mediated by configurational heterogeneity, and vary between trophic groups. Efforts to conserve insects in agricultural landscapes must therefore focus on both increasing the heterogeneity of the crop matrix by promoting crop diversity and increasing the density of field borders, while also maintaining or restoring semi-natural habitats as important source habitats for insect species.
The adoption potential of extended lactation as a strategy to reduce excess calf numbers in dairy farming
(2024) Gresham, Josephine; Reiber, Christoph; Chagunda, Mizeck G. G.
Dairy production relies predominantly on a few, selectively bred, high-yielding dairy breeds, resulting in a surplus of low-value male offspring. This situation leads to a conflict between a growing demand for milk and low appreciation for dairy calves. Extending lactation could reduce the number of calves born. This study aimed to assess the current use of extended lactation in dairy production in Southern Germany, identify the perceived potential, and determine the biological potential extended lactation has to reduce calf numbers. A survey from 2020 with 310 farmers was analysed. A total of 145 (46.8%) farmers used extended lactation. The use of extended lactation on farms correlated significantly with breed, milk yield, interest in continuing or implementing the use of extended lactation, and the indicated feasibility of extended lactation. The perceived potential was assessed by 39.8% of farmers as “high” to “very high”. A total of 17 (12.8%) farmers currently not using extended lactation were identified as potential adopters. Together with existing adopters, this could result in 52.3% of farms using extended lactation, which could biologically reduce calf numbers by 7.3% or 14.1% p.a., when extended by three or six months, respectively. This adoption potential shows that extended lactation can reduce calf numbers considerably, addressing both ethical and economic concerns in dairy farming and benefiting farmers as well as society.
Leaf gas exchange of lowland rice in response to nitrogen source and vapor pressure deficit
(2021) Vu, Duy Hoang; Stürz, Sabine; Pieters, Alejandro; Asch, Folkard
Background: In anaerobic lowland fields, ammonium (NH4+) is the dominant form of nitrogen (N) taken up by rice plants, however, with the large expansion of water-saving irrigation practices, nitrification is favored during drained periods, leading to an increased availability of nitrate (NO3−). Aim: Since the uptake and assimilation of the two N-sources differ in their demand of pho- tosynthates, leaf gas exchange may be subject to adjustments in response to N-sources, particularly at high evaporative demand, when stomatal conductance (gs ) is very sensitive. Methods: Three experiments were carried out to study leaf gas exchange of various low- land rice varieties in response to N-source at low and high vapor pressure deficit (VPD). In the first experiment, seedlings of 12 rice varieties were grown at high VPD for 3 weeks. From this, four rice varieties differing in gs and CO2 assimilation rate (A) were selected and grown for 2 weeks at low VPD, and after that, they were shifted to high VPD for 1 week, whereas in the third experiment, the same varieties were grown separately at low and high VPD conditions for 2 weeks. In all three experiments, plants were grown hydroponi- cally in nutrient solution with N-sources as sole NH4+ or NO3−. Results: At high VPD, NO3− nutrition led to a higher gs and A in four out of 12 vari- eties (IR64, BT7, NU838, and Nipponbare) relative to NH4+ nutrition, while no effect was observed at low VPD or after a short-term exposure to high VPD. Further, varieties with a high intrinsic water-use efficiency (WUEi; IR64 and BT7) showed the strongest response to N-source. Higher gs was partially supported by increased root/shoot ratio, but could not be fully explained by the measured parameters. However, higher A in NO3−-fed plants did not always result in increased plant dry matter, which is probably related to the higher energy demand for NO3− assimilation. Our results suggest that at high VPD, NO3− nutri- tion can improve leaf gas exchange in varieties having a high WUEi, provided a sufficient water supply. Conclusion: Therefore, intensified nitrification under water-saving irrigation measures may improve leaf gas exchange and the growth of rice plants under high transpirational demand. However, choice of variety seems crucial since large varietal differences were observed in response to N-source. Further, breeding strategies for genotypes adapted to aerobic soil conditions should consider responses to NO3−, potentially using gas exchange measurements as a screening tool.
Spent Pleurotus ostreatus substrate has potential for managing Fusarium wilt of banana
(2021) Ocimati, Walter; Were, Evans; Tazuba, Anthony Fredrick; Dita, Miguel; Zheng, Si-Jun; Blomme, Guy
A range of basidiomycetes including the edible mushroom Pleurotus ostreatus (Po) can suppress plant pathogens such as Fusarium spp. With the current increase in production and consumption of Po in Uganda, the spent Po substrate (SPoS) could be an alternative to manage Fusarium wilt of banana (FWB), caused by the soil borne pathogen Fusarium oxysporum f. sp. cubense, race 1 (Foc). This study determined the potential of SPoS to inhibit Foc in vitro and in potted plants. In vitro studies confirmed suppression of Foc in pure co-culture (Po vs. Foc) assays and media amended with different concentrations (0% to 50% w/v) of un-sterilized SPoS filtrates. Foc growth in the sterile SPoS filtrate was comparable to the water control, suggesting possible roles of biotic or thermolabile components of the SPoS. To further verify the suppressive effects of SPoS, pot experiments were carried out with a resistant (‘Mbwazirume’, AAA) and susceptible (‘Sukali Ndizi’, AAB) banana cultivar using both artificially and naturally infested soils. Independent of the inoculation method, SPoS significantly reduced the severity of FWB in pot experiments. Susceptible cultivar ‘Sukali Ndizi’ growing in substrates amended with SPoS showed lower (1.25) corm damage (Scale 0–5) than the un-amended control (3.75). No corm damage was observed in uninoculated controls. The resistant cultivar ‘Mbwazirume’, showed slight (0.25) corm damage only in the Foc-inoculated plants without SPoS. These findings suggest that SPoS could be used as part of the management practices to reduce the impact of FWB.
The roles of field assistant of pesticide company in Indonesia: a qualitative study
Yulianti, A; Istriningsih,; Dewi, Y A; Hanifah, V W; Herteddy, D; Suib, E; Sarwani, M
The pesticide market in Indonesia is highly competitive which leads the companies to constantly develop marketing strategies. Pesticide companies assign Field Assistants (FAs) to execute the promotional efforts and knowledge delivery to farmers to increase the sale. This study aimed to investigate FA roles as a promotional agent in technology dissemination to support their tasks in demand creation and technology adoption, respectively. The study was conducted from October to December 2020 in North Sumatra Province. Data was collected by interviewing individual FA representing five pesticide companies, both multinational and local companies. The descriptive qualitative method was used by employing an inductive theoretical model, then analyzed with coding techniques using NVivo. The result revealed that among 10 emerging roles from coding, the most dominant role was stakeholders’ engagement; whilst the least one was understanding farmers’ problems. The role also addressed an environmental issue through a stewardship program funded by the company. There were variations in the implementation of those roles among companies due to their limiting factors. Thus, FA roles are mainly working on promotional efforts embedded with extension activities in terms of knowledge transfer to farmers, technical advisory, on-farm demonstration plot, and expose or farmer field day.
Investigating potential transferability of place-based research in land system science
(2016) Václavík, Tomáš; Langerwisch, Fanny; Cotter, Marc; Fick, Johanna; Häuser, Inga; Hotes, Stefan; Kamp, Johannes; Settele, Josef; Spangenberg, Joachim H; Seppelt, Ralf
Much of our knowledge about land use and ecosystem services in interrelated social-ecological systems is derived from place-based research. While local and regional case studies provide valuable insights, it is often unclear how relevant this research is beyond the study areas. Drawing generalized conclusions about practical solutions to land management from local observations and formulating hypotheses applicable to other places in the world requires that we identify patterns of land systems that are similar to those represented by the case study. Here, we utilize the previously developed concept of land system archetypes to investigate potential transferability of research from twelve regional projects implemented in a large joint research framework that focus on issues of sustainable land management across four continents. For each project, we characterize its project archetype, i.e. the unique land system based on a synthesis of more than 30 datasets of land-use intensity, environmental conditions and socioeconomic indicators. We estimate the transferability potential of project research by calculating the statistical similarity of locations across the world to the project archetype, assuming higher transferability potentials in locations with similar land system characteristics. Results show that areas with high transferability potentials are typically clustered around project sites but for some case studies can be found in regions that are geographically distant, especially when values of considered variables are close to the global mean or where the project archetype is driven by large-scale environmental or socioeconomic conditions. Using specific examples from the local case studies, we highlight the merit of our approach and discuss the differences between local realities and information captured in global datasets. The proposed method provides a blueprint for large research programs to assess potential transferability of place-based studies to other geographical areas and to indicate possible gaps in research efforts.
Qualitative modeling for bridging expert-knowledge and social-ecological dynamics of an East African savanna
(2021) Cosme, Maximilien; Hély, Christelle; Pommereau, Franck; Pasquariello, Paolo; Tiberi, Christel; Treydte, Anna; Gaucherel, Cédric
Sub-Saharan social-ecological systems are undergoing changes in environmental conditions, including modifications in rainfall pattern and biodiversity loss. Consequences of such changes depend on complex causal chains which call for integrated management strategies whose efficiency could benefit from ecosystem dynamic modeling. However, ecosystem models often require lots of quantitative information for estimating parameters, which is often unavailable. Alternatively, qualitative modeling frameworks have proved useful for explaining ecosystem responses to perturbations, while only requiring qualitative information about social-ecological interactions and events and providing more general predictions due to their validity for wide ranges of parameter values. In this paper, we propose the Ecological Discrete-Event Network (EDEN), an innovative qualitative dynamic modeling framework based on “if-then” rules generating non-deterministic dynamics. Based on expert knowledge, observations, and literature, we use EDEN to assess the effect of permanent changes in surface water and herbivores diversity on vegetation and socio-economic transitions in an East African savanna. Results show that water availability drives changes in vegetation and socio-economic transitions, while herbivore functional groups have highly contrasted effects depending on the group. This first use of EDEN in a savanna context is promising for bridging expert knowledge and ecosystem modeling.
Low glyphosate doses change reproduction and produce tolerant offspring in dense populations of Hordeum vulgare
(2021) Belz, Regina G; Sinkkonen, Aki
BACKGROUND: Low toxin doses that do not affect mean responses in plant populations can still change the growth of subpopulations. Studies covering vegetative stages ascribed fast-growing plants higher thresholds for growth stimulation and inhibition, compared with the rest of the population. We hypothesized that such selective effects also play a role after reproduction; that is, the offspring of glyphosate-treated tolerant, fast-growing phenotypes is more tolerant than the offspring of untreated plants. An experimental, high-density barley population was exposed to a range of glyphosate concentrations in the greenhouse, and reproduction and final growth were analyzed for selective effects. Therefore, F0, F1 treated and F1 non-treated offspring were re-exposed to glyphosate. RESULTS: Low doses of glyphosate inhibited the growth and reproduction of slow-growing plants at concentrations that did not change the population mean. Concentrations that inhibited average-sized plants hormetically increased the biomass and seed yield of fast-growing plants. Compared with F0 and F1 non-treated offspring, F1-treated offspring from hormetically stimulated fast-growing plants were more glyphosate tolerant. Hence, a pesticide can shape the reproductive pattern of a plant population and alter offspring tolerance at concentrations that have no effect on average yield. CONCLUSIONS: Toxin levels that do not change the population mean still alter the reproductive output of individuals. Sensitive phenotypes suffer, whereas the reproduction of tolerant phenotypes is boosted compared with toxin-free conditions. Because glyphosate is one of the leading herbicides in the world, tolerant phenotypes may benefit from current agricultural practices. If these results apply to other toxicants, low toxin doses may increase the fitness of tolerant phenotypes in a way not previously anticipated.
Land use land/cover change reduces woody plant diversity and carbon stocks in a lowland coastal forest ecosystem, Tanzania
(2022) Ntukey, Lucas Theodori; Munishi, Linus Kasian; Treydte, Anna Christina
The East-African lowland coastal forest (LCF) is one of Africa’s centres of species endemism, representing an important biodiversity hotspot. However, deforestation and forest degradation due to the high demand for fuelwood has reduced forest cover and diversity, with unknown consequences for associated terrestrial carbon stocks in this LCF system. Our study assessed spatio-temporal land use and land cover changes (LULC) in 1998, 2008, 2018 in the LCF ecosystem, Tanzania. In addition, we conducted a forest inventory survey and calculated associated carbon storage for this LCF ecosystem. Using methods of land use change evaluation plug-in in QGIS based on historical land use data, we modelled carbon stock trends post-2018 in associated LULC for the future 30 years. We found that agriculture and grassland combined increased substantially by 21.5% between the year 1998 and 2018 while forest cover declined by 29%. Furthermore, forest above-ground live biomass carbon (AGC) was 2.4 times higher in forest than in the bushland, 5.8 times in the agriculture with scattered settlement and 14.8 times higher than in the grassland. The estimated average soil organic carbon (SOC) was 76.03 ± 6.26 t/ha across the entire study area. Our study helps to identify land use impacts on ecosystem services, supporting decision-makers in future land-use planning.
Land use/cover change reduces elephant habitat suitability in the Wami Mbiki–Saadani Wildlife corridor, Tanzania
(2022) Ntukey, Lucas Theodori; Munishi, Linus Kasian; Kohi, Edward; Treydte, Anna Christina
Wildlife corridors are critical for maintaining the viability of isolated wildlife populations and conserving ecosystem functionality. Anthropogenic pressure has negatively impacted wildlife habitats, particularly in corridors between protected areas, but few studies have yet quantitatively assessed habitat changes and corresponding wildlife presence. We quantified land use/land cover and human–elephant conflict trends over the past two decades in the Wami Mbiki–Saadani (WMS) wildlife corridor, Tanzania, using RS and GIS combined with human–wildlife conflict reports. We designed landscape metrics and habitat suitability models for the African savanna elephant (Loxodonta africana) as a large mammal key species in the WMS ecosystem. Our results showed that forest cover, a highly suitable habitat for elephants, decreased by 3.0% between 1998 and 2008 and 20.3% between 2008 and 2018. Overall, the highly suitable habitat for elephants decreased by 22.4% from 1998 to 2018, when it was scarcely available and when small fragmented patches dominated the unprotected parts of the corridor. Our findings revealed that large mammalian habitat conservation requires approaches beyond habitat-loss detection and must consider other facets of landscape patterns. We suggest strengthening elephant habitat conservation through community conservation awareness, wildlife corridor mapping, and restoration practices to ensure a sustainable pathway to human–wildlife coexistence.
Do biotic and abiotic factors influence the prevalence of a common parasite of the invasive alien ladybird Harmonia axyridis?
(2022) Haelewaters, Danny; Hiller, Thomas; Ceryngier, Piotr; Eschen, René; Gorczak, Michał; Houston, Makenna L.; Kisło, Kamil; Knapp, Michal; Landeka, Nediljko; Pfliegler, Walter P.; Zach, Peter; Aime, M. Catherine; Nedvěd, Oldřich
Hesperomyces virescens (Ascomycota, Laboulbeniales), a fungal ectoparasite, is thus far reported on Harmonia axyridis from five continents: North and South America, Europe, Africa, and Asia. While it is known that He. virescens can cause mortality of Ha. axyridis under laboratory conditions, the role of biotic and abiotic factors in influencing the distribution of He. virescens in the field is unknown. We collected and screened 3,568 adult Ha. axyridis from 23 locations in seven countries in Central Europe between October and November 2018 to test the effect of selected host characters and climate and landscape variables on the infection probability with He. virescens. Mean parasite prevalence of He. virescens on Ha. axyridis was 17.9%, ranging among samples from 0 to 46.4%. Host sex, climate, and landscape composition did not have any significant effect on the infection probability of He. virescens on Ha. axyridis. Two color forms, f. conspicua and f. spectabilis, had a significantly lower parasite prevalence compared to the common Ha. axyridis f. novemdecimsignata.
Effects of type of concentrate and timing of supplementation on feed intake, nitrogen use, and performance in lactating dairy cows grazing an alfalfa-ryegrass sward
(2022) Dickhöfer, Uta; Sainz-Sanchez, Pedro Alan; Rojas, Gustavo; Castro-Montoya, Joaquín Miguel; Gomez, Carlos
The aim was to analyze the effects of two cereal grains differing in nutritional composition and starch degradation characteristics and the timing of their supplementation on feed intake, rumen microbial protein synthesis (MPS), performance, and nitrogen use of lactating dairy cows grazing an alfalfa-ryegrass sward. Four dietary treatments were tested in 24 lactating Brown Swiss cows in an incomplete 4 × 3 Latin square design. Cows were supplemented with 3.5 kg/d (as-fed basis) of a corn-based or an oat-based concentrate mixture (CM), of which either the majority (2.5 vs. 1.0 kg/d) was offered before or after grazing. Feed intake was similar across diets, but the interaction between type of CM and timing of supplementation affected eating time (p = 0.010), milk protein (p = 0.013) and energy-corrected milk yields (p = 0.025), efficiency of rumen MPS (p = 0.094), and nitrogen use efficiency (p = 0.081). Most of these variables were greater when the majority of the corn-based CM was offered after grazing and the oat-based CM before grazing. Supplementing slowly degradable starch sources after and rapidly degradable starch sources before grazing may improve the efficiency of rumen MPS, milk performance, and nitrogen use efficiency in dairy cows grazing alfalfa-ryegrass swards.

Browse

Recent Submissions