Thesis (M.A.)--Boston University

This thesis summarizes knowledge about mycotoxins, with focus to ochratoxin A. It also summarizes its tolerable levels of food intake, detoxification and analytical methods for mycotoxins. The work also includes a chapter describing liposomes that were used for the analysis of ochratoxin A by liposomal electrokinetic capillary electrophoresis (LECK). The practical part includes the analysis of ochratoxin A from Aspergillus ochraceus Wilhelm and Aspergillus melleus Yukawa fungi cultivated on a rye and optimization of the method for analysis of ochratoxin A based on liposomes of different compositions. By capillary zone electrophoresis, ochratoxin A is not sufficiently separated and detected in the extracted mixture; conversely, when liposome solutions are used, different migration behavior can be achieved while stabilizing ochratoxin A in solution due to amphiphilic interactions between mycotoxins and liposomes. Therefore, the LEKC method was used for this work. The most suitable liposome composition has been shown to be molar ratios of 25% cholesterol (membrane stabilization) / 50% 2-oleoyl-1-palmitoyl-sn-glycerol 3-phosphocholine (main zwitterionic lipid) / (25% 1,2-diacyl-sn-glycerol)-3-phospho-L-serine (introduction of negative charge).

Noch vor 50 Jahren stand Roggen an erster Stelle im Getreideanbau, erst mit Abstand folgte der Weizen . Gerste wurde meist nur als Sommerfrucht angebaut und der Mais war noch ein Exot. Die Pflanzenzüchtung bewirkte eine grundlegende Änderung der Anbaugewohnheiten. Roggen erwies sich bei der züchterischen Verbesserung als schwieriger und sein langes Stroh störte bei der Ernte mit dem Mähdrescher. Roggen wurde deshalb auf die geringerwertigeren Böden mit hohem Sandanteil abgedrängt. Durch eine neue Methode der Pflanzenzüchtung, die Hybridzüchtung, kann Roggen heute im Ertrag auf vielen Standorten wieder mit dem Weizen konkurrieren. Mit der vorliegenden Veröffentlichung wird erläutert, ob höhere Roggenanteile in der Ferkel- und Mastschweinefütterung vertretbar sind.

Horseweed (Conyza canadensis (L.) Cronq.) is prevalent in Kentucky and can be difficult to control. Research has shown multiple weed control methods to be more sustainable than relying on chemical control alone, so the use of multiple methods for horseweed management was examined in this study. The main objective was to determine best practice(s) to reduce horseweed prior to soybean [Glycine max (L.) Merr.]. Treatments included: fall-planted cover crop [CC; cereal rye (Secale cereale L.) or none], fall-applied herbicide (saflufenacil or none), and spring-applied herbicides (dicamba, 2,4-D ester, or none). We hypothesized horseweed densities would be reduced the most where all factors were combined. Saflufenacil suppressed horseweed densities from application through March, when densities increased due to a lack of competition from other winter weeds. Spring herbicides decreased horseweed densities until soybeans reached V1 in 2017, but in 2018 lost efficacy after CC termination. CC alone resulted in the longest horseweed suppression. The combination of spring herbicides and CC usually reduced horseweed densities to near zero between the CC termination and soybean planting. However, some low densities seen soon after soybean planting could be problematic. Further research must be conducted to determine the best integrated horseweed management system until soybean canopy closure.

Five day old dark-grown seedlings of Secale cereale variety "coup;ar" p:rown at 20 C were subjected to hardening at 2 C "!.n daily increments from 0 to 7 days, to temperature stress at -5 C for 0, 1, and 3 days, and to recovery at 20 C for 0, I, and J days. Unhardened plants were killed by temperature stress but as the time of hardening increased fewer plants were killed. After 5 days of hardening all plants survived subsequent freezing stress. Mitochondria were isolated from the plants after they received various combinations of the three temperature treatments. There were 8 hardening levels, 3 stress levels, and 3 recovery levels giving a total of 8x3x30 72 treatments. Mitochondria from unstressed plants exhibited steady ADPIO ratios, RC ratios, and rate of state 3 respiration over the whole range of hardening and recovery times. Mitochondria from stressed plants were totally inactive with 0 or one day of hardening but as the time of hardening increased so did ADP: O ratio, R~ ratio, and ratp of state J respiratIon. After 5 days of hardenjng mitochondrla from hardened then stressed plants reached a maxImum level of activity. Evidently there was some change 1n the mttochondria during the hardening phase.

Leaf tissue of diploid, triploid, and tetraploid tomatoes (var. UF-36) and diploid and tetraploid barley (var. Steel and Midsummer) were analyzed for total chlorophyll, soluble protein, dry weight, ribulose-1,5-diphosphate carboxylase, phosphoribulokinase, and peroxidase. Polyploidy caused a slight increase of all factors in Midsummer rye, had a variable effect on Steel rye and Everest barley, and caused a reduction in tomatoes and Barbless barley when the factors were determined on a fresh weight basis. In tomatoes, if the ribulose-1,5-diphosphate carboxylase activity was determined on protein content, dry weight or cell number the tetraploid form had higher activity than the diploid form. The interaction between polyploidy and the leaf tissue changed with the time of leaf initiation and also with the age of the leaf. The specific activity of ribulose-1,5-diphosphate carboxylase did not change with changes in chromosome number. However, there was a large drop in the specific activity in all plants assayed between the middle of October and the middle of November.

Agroecosystem sustainability as a framework for agriculture production systems requires attention to detail to multiple facets of the underlying production system. Production systems must achieve optimal cash crop yields while remaining profitable. Likewise, production practices must be tailored to reduce its environmental footprint. Identifying practices that encourage improved soil physical and chemical properties while maintaining yields have largely been challenging. Cover crops have been an integral part of the conversation regarding practices that can generally improve those properties of soil responsible for overall soil health. Use of winter cereal cover crops (WCCC’s) have shown promise as a tool for reducing soil and nutrient run-off, thereby reducing nitrogen (N) and phosphorus (P) nonpoint source pollution in the Upper Mississippi River Basin (UMRB). However, corn-cash crop yield penalties are often incurred following the use of WCCC’s such as winter cereal rye (Secale cereal) (WCR), as N is immobilized by cover crop residues in the decomposition processes. Additionally, traditional planting methods of cover crops have resulted in reductions of harvestable populations of corn and soybeans. These problems indicate a necessity for novel cover crop planting methods that reduce the consequential outcomes of implementing traditional cover crop practices. Using a method called “Skipping the corn row” (STCR), otherwise identified as “precision planted” cover crops, we aimed to reduce the cash crop yield-limiting interactions of cover crop residues within the cash crop row. We hypothesized that removing cover crop biomass from the subsequently planted cash crop row (chapter 1) could minimize N immobilization by residues, thereby increasing our subsequent yield potential and economic optimum return to N (EORN). In novel cover crop planting methods preceding soybeans (chapter 3), our hypothesis indicated that mixtures of WCR and crimson clover (Trifolium incarnatum) would impact biomass accumulation of weed communities, while novel measures that allowed for reduced seeding rates would permit competitive soybean yields while reducing input costs for cover crop seed. Chapter 2 focused on interseeding mixtures of WCR and crimson clover, where we hypothesized that residual rates would marginally impact percent cover of WCR and crimson clover mixtures. Our results indicated, in chapter one, that reducing seeding rate by using STCR planting method did indeed drive seed cost savings while improving yield and EORN in comparison to a traditionally planted cover crop. Our results in chapter 3 also indicated reduced seeding rates found in novel planting methods improved the on-farm economics of using cover crops while maintaining healthy soybean yields. Lower-than-average rainfall accumulations later in the growing season coupled with cover crop residues likely influenced soil moisture retention, benefiting the cash crop during the dry spell, helping maintain yields. Interseeding methods, as studied in chapter 2, did not show any significant impact on corn grain yield or yield components. Subsequently, half- and full-rate residual herbicides did not impact percent cover of cover crops. However, use of residual herbicides should be consistent with all herbicide labels and laws, and producers should use label-recommended amounts to maintain maximum efficacy of herbicides and to prevent resistant weed populations. Also, interseeded cover crops failed to successfully establish, resulting in minimal cover crop biomass in later sampling dates.

Cover crops are often planted during the fallow periods of cash crop harvests to cover the soil and reduce erosion but also to provide other ecosystem benefits including capturing residual nutrients and thus, reducing environmental losses of nitrogen (N) and phosphorus (P) in agroecosystems. Among these cover crops, winter rye (Secale cereale) is popular due to its winter hardiness and relatively cheap seed costs. However, growers in the Midwest, USA are reluctant to use winter rye prior to corn (Zea mays L.) due to the potential yield penalty in corn. This thesis introduces two strategies that could minimize winter rye’s effect on corn while providing nutrient loss reduction benefits are precision planting and reducing the seeding rate of winter rye ahead of corn. One study evaluates whether precision planting (planting winter rye strategically to avoid intersecting zones with corn) of winter rye at low seeding rate (37.5 kg ha-1) could produce similar cover crop biomass and quality to normal planted winter rye (50 kg ha-1) and if precision planting can improve performance and N requirement of corn (Chapter 1). The study was conducted in central Indiana during 2020-2021 (CIN21), and southern Illinois during 2021-2022 (SIL22), and 2022-2023 (SIL23) growing seasons. The experiment was arranged in a randomized block design with split plot arrangement. Main plots were three cover crops (a no-cover crop control (NoCC), conventional planted winter rye (CR), and precision planted winter rye (PR). Subplots were six rates of N fertilizer that ranged from 0-280 kg ha-1 for the CIN21 and 0-359 kg ha-1 for SIL22 and SIL23. Our results indicated that shifting from normal planting to precision planting resulted in similar cover crop biomass production with limited effect on winter rye quality [N concentration, Carbon (C):N ratio] and N and C accumulation. In CIN21, the no-cover crop control had higher yield and lower N requirements which was consistent with those of SIL22. The economic optimum rate of N (EORN) was below the typical recommended range for central Indiana and was above the recommended range for southern Illinois. Precision planting resulted in a slight increase in corn yield and N requirement, but overall was more profitable than normal planting due to a reduction in the number of seeds required and higher corn to fertilizer prices. Therefore, we recommend that (i) decision support tools for N management in corn should be revised for addition of cover crops in the Midwest, and (ii) precision planting should be implemented instead of normal planting for greater economic benefit. Future research should evaluate ecosystem services of precision vs. normal planting of winter rye over time. The other study evaluates whether planting method of winter rye (precision vs. conventional) at medium and low seeding rates of winter rye influence cover crop biomass production, N and C concentrations and accumulations, and corn performance (Chapter 2). A trial was conducted in 7 site-yrs in Indiana and Illinois during 2020-2021, 2021-2022, and 2022-2023 growing seasons. The trial was arranged in a randomized complete block design with four replicates. Cover crops [conventional planting (CR) and precision planting (PR)] were factorially arranged with two seeding rates (18.75 vs. 37.5 kg ha-1) for PR and (25 vs. 50 kg ha-1) for CR. Two extra treatments were included as control which were no-cover crop with zero-N and a 224 kg N ha-1 addition to corn. Cover crop biomass, C, N, their uptake, and C:N ratio were evaluated along with corn plant population, and corn grain yield. Our results indicated that winter rye had similar aboveground biomass, N uptake, and C accumulation regardless of planting method and seeding rate suggesting a precision planting at low seeding rate is most economical for cover crop establishment. Corn plant population was only affected by winter rye in one site-yr (CIL23) in which precision planting did not help with minimizing the negative effect of winter rye on corn population. In this study, lack of N fertilization did not decrease corn population but significantly reduced corn grain yield in all site-yrs. Corn grain yield was similar among cover crop treatments (with exception of no cover crop no N) but in one of the site-yrs, precision planting at 18.75 kg ha-1 resulted in greater corn yield than the no-cover crop with 224 N ha-1. We concluded that growers that plant winter rye prior to corn could use precision planting at a seeding rate of 18.75 kg ha-1 to take up residual soil N with limited interference with corn production at a reduced cost compared to conventional winter rye management.

Improved N management is required to enhance crop productivity, while reducing concomitant losses. Research was conducted for 4-y studying winter cover crops. Three legume species grown alone or with either cereal rye (Secale cereale) or ‘Tillage Radish®’ (Raphanus sativus L.) were used to quantify cover crop biomass and N content plus their effects on corn grain yield and N recovery. The effects of these cropping systems on selected soil health indicators was also determined. Rye bicultures enhanced biomass production, but antagonistically affected corn performance. Radish inclusion resulted in equal or greater cover crop N than rye. In year 3, the addition of radish across legume species increased corn N content (10.6 kg ha-1) and grain yield (1050 kg ha-1). Although cover crops did not affect soil bulk density, both bicultures increased soil C/N. The legume-radish association offers a novel practice towards improving crop performance and soil quality.

La alta frecuencia de cultivos de oleaginosas con moderados aportes y persistencia de residuos podría limitar la normal productividad de los suelos. La inclusión de cultivos invernales (utilizados como cultivos de cobertura, CC) en la región semiárida y subhúmeda pampeana sería una alternativa para proveer de residuos ricos en C y promover al desarrollo y al mantenimiento de la cobertura de los suelos. Pero se reconoce que el consumo hídrico de éstos podría interferir en la oferta de agua para el cultivo siguiente. El objetivo de este estudio fue evaluar la eficiencia en la producción de materia seca (MS) de cereales de invierno utilizados como CC y sus efectos sobre los contenidos de agua útil y nitratos en suelos diferenciados por el régimen hídrico. Los estudios se desarrolla-ron en 4 sitios experimentales [Luan Toro (LP) (Haplustol Entico, precipitación 624 mm), Dorila (LP) (Haplustol Entico, precipitación 873 mm), General Villegas (BA) (Hapludol Thapto Árgico, precipitación 906 mm) y General Pinto (BA) (Argiudol Típico, precipitación 1116 mm)]. Los tratamientos fueron: Secale cereale (C), Lolium multiflorum (R), Avena sativa (A) y un tratamiento Testigo, sin CC (T). La producción de MS al momento del secado de los CC varió entre 1226 y 10500 kg ha-1. Se observó una gran influencia del régimen hídrico de los suelos sobre la producción del MS de los CC. El contenido de agua total al momento de la siembra explicó el 57 % de la variabilidad de la producción de MS, mientras que el contenido de agua total en el suelo a la siembra más las precipitaciones durante el ciclo de desarrollo de los CC, explicó el 89 % de la variabilidad. En todos los sitios el centeno produjo la mayor cantidad de MS, seguida por la avena y el rye grass. La mayor variación se dio dentro del mismo sitio, entre los años de evaluación. El uso consuntivo hasta el momento del secado varió entre 88 y 299 mm. La especie con mayor eficiencia de uso de agua fue el centeno, alcanzando su máximo valor en el sitio de General Pinto (54 kg MS mm-1). Los valores de resistencia a la penetración fueron mayores bajo los tratamientos con CC y tuvieron una relación significativa con los contenidos hídricos del suelo. Sólo en el sitio Dorila los mayores valores fueron registrados en el tratamiento T, sin comprobarse relación significativa entre variaciones en la RP y los contenidos hídricos del suelo. Los contenidos de N-NO3- en el suelo fueron mayores en los tratamientos testigos, independientemente del sitio, en tanto que los contenidos de N de la biomasa variaron entre 29 y 275 kg ha-1; con mayores valores para el centeno. La producción de soja varió entre 1069 y 5346 kg ha-1 y no se afectó por la inclusión de CC. Estudios futuros deben, en el largo plazo, contemplar el beneficio de la incorporación de CC sobre las propiedades físicas y químicas del suelo en sistemas agrícolas de la región semiárida y subhúmeda pampeana dedicados al cultivo de soja. / The soil productivity can be limited because of a frequent presence of oil crops and because of their little residue cover production and persistence on the soils. In the semiarid and subhumid Pampas region, the use of winter cover crops (CC) could provide residues with high C contents and maintain an adequate soil residue cover. But, the soil water use of the CC during the winter season can modify the normal soil water availability for the follo-wing crop. The objective of this research was to evaluate the dry matter (MS) production efficiency of winter cereals cultivated as CC and their effect on the soil available water and soil nitrates under two soil moisture regimes. The study was performed in four experimental sites: Luan Toro (La Pampa) (Entic Haplustoll, mean anual rainfall of 624 mm), Dorila (La Pampa) (Entic Haplustoll, mean anual rainfall of 873 mm), General Villegas (Buenos Aires) (Thapto-argic Hapludoll, mean anual rainfall of 906 mm)and General Pinto (Buenos Aires) (Typic Argiudoll, mean anual rainfall of 1116 mm). The treatments were: Rye [Secale cereale (C)], Rye grass [Lolium multiflorum (R)] and oat [Avena sativa (A)] and an untreated control without CC (T). The MS production at the moment of killing the CC varied between 1226 and 10500 kg ha-1. A strong effect of the soil water regime on the MS production of the CC was observed. The soil water content at the moment of seeding the CC explained 57 % of the MS production and the soil water content at seeding and rainfalls during the CC growing season explained almost 89 % of the variability in MS production. In the four locations, rye showed the greater MS production followed by oat and rye grass. The greater variability was observed within each of the sites and the studied seasons. The water uptake at the moment of killing the CC varied between 88 and 299 mm. Rye was the cereal with greater water use efficiency with a highest value in General Pinto with 54 kg of MS mm-1. The soil penetration resistance (RP) values were higher under CC treatments and negatively related with the soil mois-ture contents. Only in Dorila the highest values of RP were observed in the control treatment without a significant relationship between them and the soil water contents. The soil N-NO3- contents were greater in the T than in the CC treatments. The N content of the CC biomass varied between 29 and 75 kg ha-1 achieving greater values with rye. The soybean grain production varied between 1069 and 5346 kg ha-1 without differences due to the CC treatments. Future studies should study the effects of the CC use of physical and chemical soil properties in agricultural systems from the semiarid and subhumid pampas region under continuous soybean crop production.