Uptake and fate of hexahydro-1,3,5-trinitro-1,3,5-triazine by Chrysopogon zizanioides

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a nitramine compound that has been used heavily by the military as an explosive. Manufacturing, use, and disposal of RDX have led to several contamination sites across the United States. RDX is both persistent in the environment and a threat to human health, making its remediation vital. The use of plants to extract RDX from the soil and metabolize it once it is in the plant tissue, is being considered as a possible solution. In the present study, the tropical grass Chrysopogon zizanioides was grown hydroponically in the presence RDX at 3 different concentration levels: 0.3, 1.1, and 2.26 ppm. The uptake of RDX was quantified by high performance liquid chromatography (HPLC) analysis of media samples taken every 6 hr during the first 24 hr and then daily over a 30-day experimental period. A rapid decrease in RDX concentration in the media of both controls and plant treatments was seen within the first 18 hours of the experiment with the greatest loss in RDX over time occurring within the first 6 hours of exposure. The loss was similar in both controls and plant exposures and possibly attributed to rapid uptake by the containers. A plant from one treatment at each of the three concentrations was harvested at Day 10, 20 and 30 throughout the experiment and extracted to determine the localization of RDX within the tissue and potentially identify any metabolites on the basis of differing retention times. Of the treatments containing 0.3, 1.1, and 2.26 ppm RDX, 13.1%, 18.3%, and 24.2% respectively, was quantified in vetiver extracts, with the majority of the RDX being localized to the roots. All plants not yet harvested were harvested on Day 30 of the experiment. A total of three plants exposed to each concentration level as well as the control, were extracted and analyzed with HPLC to determine amount of RDX taken up, localization of RDX within the plant tissue, and potentially identify any metabolites. Phytotoxicity of RDX to vetiver was also monitored. While a loss in biomass was observed in plants exposed to all the different concentrations of RDX, control plants grown in media not exposed to RDX showed the greatest biomass loss of all the treatments. There was also little variation in chlorophyll content between the different concentration treatments with RDX. This preliminary greenhouse study of RDX uptake 10 by Chrysopogon zizanioides will help indicate the potential ability of vetiver to serve as a plant system in the phytoremediation of RDX.

Aluminum toxicity to tropical montane forest tree seedlings in southern Ecuador: response of biomass and plant morphology to elevated Al concentrations

In acid tropical forest soils (pH < 5.5) increased mobility of aluminum might limit aboveground productivity. Therefore, we evaluated Al phytotoxicity of three native tree species of tropical montane forests in southern Ecuador. An hydroponic dose-response experiment was conducted. Seedlings of Cedrela odorata L., Heliocarpus americanus L., and Tabebuia chrysantha (Jacq.) G. Nicholson were treated with 0, 300, 600, 1200, and 2400 mu M Al and an organic layer leachate. Dose-response curves were generated for root and shoot morphologic properties to determine effective concentrations (EC). Shoot biomass and healthy leaf area decreased by 44 % to 83 % at 2400 mu M Al, root biomass did not respond (C. odorata), declined by 51 % (H. americanus), or was stimulated at low Al concentrations of 300 mu M (T. chrysantha). EC10 (i.e. reduction by 10 %) values of Al for total biomass were 315 mu M (C. odorata), 219 mu M (H. americanus), and 368 mu M (T. chrysantha). Helicarpus americanus, a fast growing pioneer tree species, was most sensitive to Al toxicity. Negative effects were strongest if plants grew in organic layer leachate, indicating limitation of plant growth by nutrient scarcity rather than Al toxicity. Al toxicity occurred at Al concentrations far above those in native organic layer leachate.

Aluminum toxicity in a tropical montane forest ecosystem in southern Ecuador

Aluminum phytotoxicity frequently occurs in acid soils (pH < 5.5) and was therefore discussed to affect ecosystem functioning of tropical montane forests. The susceptibility to Al toxicity depends on the sensitivity of the plant species and the Al speciation in soil solution, which can vary highly depending e.g., on pH, ionic strength, and dissolved organic matter. An acidification of the ecosystem and periodic base metal deposition from Saharan dust may control plant available Al concentrations in the soil solutions of tropical montane rainforests in south Ecuador. The overall objective of my study was to assess a potential Al phytotoxicity in the tropical montane forests in south Ecuador. For this purpose, I exposed three native Al non-accumulating tree species (Cedrela odorata L., Heliocarpus americanus L., and Tabebuia chrysantha (Jacq.) G. Nicholson) to increased Al concentrations (0 – 2400 μM Al) in a hydroponic experiment, I established dose-response curves to estimate the sensitivity of the tree species to increased Al concentrations, and I investigated the mechanisms behind the observed effects induced by elevated Al concentrations. Furthermore, the response of Al concentrations and the speciation in soil solution to Ca amendment in the study area were determined. In a final step, I assessed all major Al fluxes, drivers of Al concentrations in ecosystem solutions, and indicators of Al toxicity in the tropical montane rainforest in Ecuador in order to test for indications of Al toxicity. In the hydroponic experiment, a 10 % reduction in aboveground biomass production occurred at 126 to 376 μM Al (EC10 values), probably attributable to decreased Mg concentrations in leaves and reduced potosynthesis. At 300 μM Al, increased root biomass production of T. chrysantha was observed. Phosphorus concentrations in roots of C. odorata and T. chrysantha were significantly highest in the treatment with 300 μM Al and correlated significantly with root biomass, being a likely reason for stimulated root biomass production. The degree of organic complexation of Al in the organic layer leachate, which is central to plant nutrition because of the high root density, and soil solution from the study area was very high (mean > 99 %). The resulting low free Al concentrations are not likely to affect plant growth, although the concentrations of potentially toxic Al3+ increased with soil depth due to higher total Al and lower dissolved organic matter concentrations in soil solutions. The Ca additions caused an increase of Al in the organic layer leachate, probably because Al3+ was exchanged against the added Ca2+ ions while pH remained constant. The free ion molar ratios of Ca2+:Al3+ (mean ratio ca. 400) were far above the threshold (≤ 1) for Al toxicity, because of a much higher degree of organo-complexation of Al than Ca. High Al fluxes in litterfall (8.8 – 14.2 kg ha−1 yr−1) indicate a high Al circulation through the ecosystem. The Al concentrations in the organic layer leachate were driven by the acidification of the ecosystem and increased significantly between 1999 and 2008. However, the Ca:Al molar ratios in organic layer leachate and all aboveground ecosystem solutions were above the threshold for Al toxicity. Except for two Al accumulating and one non-accumulating tree species, the Ca:Al molar ratios in tree leaves from the study area were above the Al toxicity threshold of 12.5. I conclude that toxic effects in the hydroponic experiment occurred at Al concentrations far above those in native organic layer leachate, shoot biomass production was likely inhibited by reduced Mg uptake, impairing photosynthesis, and the stimulation of root growth at low Al concentrations can be possibly attributed to improved P uptake. Dissolved organic matter in soil solutions detoxifies Al in acidic tropical forest soils and a wide distribution of Al accumulating tree species and high Al fluxes in the ecosystem do not necessarily imply a general Al phytotoxicity.

Growth response to ozone of annual species from Mediterranean pastures

Ozone (O3) phytotoxicity has been reported on a wide range of plant species. However, scarce information has been provided regarding the sensitivity of semi-natural grassland species, especially those from dehesa Mediterranean grasslands, in spite of their great biological diversity and the high O3 levels recorded in the region. A screening study was carried out in open-top chambers (OTCs) to assess the O3-sensitivity of representative therophytes of these ecosystems based on the response of selected growth-related parameters. Three O3 treatments and 3 OTCs per treatment were used. Legume species were very sensitive to O3, because 78% of the tested species showed detrimental effects on their total biomass relative growth rate (RGR) following their exposure to O3. The Trifolium genus was particularly sensitive showing O3-induced adverse effects on most of the assessed parameters. Gramineae plants were less sensitive than Leguminosae species because detrimental effects on total biomass RGR were only observed in 14% of the assessed species. No relationship was found between relative growth rates when growing in clean air and O3 susceptibility. The implications of these effects on the performance of dehesa acidic grasslands and on the definition of ozone critical levels for the protection of semi-natural vegetation are discussed.

Fabricación, caracterización y utilización de biochar como sustituto de la turba en la preparación de sustratos de cultivo

Este trabajo aborda el estudio del uso de restos de poda, lodos de depuradora y diferentes biochares obtenidos a partir de dichos residuos, así como biochar comercial, como componentes de sustratos de cultivo en sustitución de la turba. Para ello, se han llevado a cabo varios experimentos usando dichos residuos originales y pirolizados, de forma individual o mezclándolos en distintas proporciones con turba con el fin de estudiar sus características químicas e hidrofísicas, su posible fitotoxicidad y el cultivo en macetas de Lactuca sativa. Los resultados obtenidos indican que es posible preparar sustratos de cultivo adecuados a partir de algunos de estos materiales, logrando así una forma de recuperación y valorización de los mismos, a la vez que se minimiza el consumo de turba. En general, la adición de biochar de restos de poda a la turba mejora la germinación y aumenta el crecimiento de Lactuca sativa respecto a la utilización de turba sola. ABSTRACT This research deals with the study of the use of pruning wastes, sewage sludges and different biochars obtained from these materials, as well as a commercial biochar, as growing media components to replace peat. Several experiments were conducted using original wastes and pyrolyzed ones, individually or mixed in different proportions with peat, in order to study their chemical and hydrophysical characteristics, its possible phytotoxicity and the pot cultivation of Lactuca sativa. The results obtained indicate that it is possible to prepare suitable growing media from some of these materials, not only achieving a recovery and valorisation of them, but also minimizing the consumption of peat. In general, the addition of pruning waste biochar to peat improves germination and increases the growth of Lactuca sativa in comparison with peat alone.

Análisis de la degradación, desintegración y biodegradabilidad de bolsas de poliéster y almidón en compostaje de residuos urbanos: escalas de laboratorio e industrial

El principal objetivo de esta tesis es verificar que las bolsas biodegradables de copoliéster (PBAT) con base de almidón (UNE 13432: 2001) alcanzan los niveles de degradación y desintegración requeridos para su certificación (%D= ≥ 90%), medido en condiciones reales de compostaje industrial. Para lograr mayor representatividad, los ensayos se han realizado en dos plantas de tratamiento de residuos urbanos en las que se aplican las técnicas de compostaje más comunes en el ámbito europeo y nacional, pila y túnel, mediante el compostaje de la FORSU. Se llevaron a cabo dos tipos de ensayos. Por un lado se realizó un ensayo escala de laboratorio (ISO 14855), orientado como indicador de la biodegradabilidad del polímero en el formato bolsa comercializado. Por otro lado, se desarrollaron una batería de ensayos realizados en dos plantas de compostaje de residuos urbanos: el Centro de Tratamiento de Residuos de Torija (Ávila), que realiza el compostaje mediante pila volteada, y el Centro de Tratamiento de Residuos de Arenas de San Pedro (Ávila), que realiza el compostaje en túnel. Para la obtención de resultados se han contrastado parámetros como el porcentaje de biodegradación (%B), el porcentaje de desintegración (%D), degradación superficial de las muestras, calidad de la FORSU inicial (caracterizaciones y análisis físico-químico) y calidad del MB final (análisis físico-químico e IG). Atendiendo al objetivo general se demuestra que las bolsas de copoliéster con base de almidón certificadas (UNE EN 13432:2001) han alcanzado el 94,37% ± 0,007% de desintegración en la planta de compostaje de FORSU con pila volteada; y el 86,36% ± 0,151% en la planta de compostaje de FORSU con túnel estático. A pesar de la aparente diferencia, el resultado del análisis concluye que no existen diferencias estadísticamente significativas entre técnicas de compostaje. La presencia de impropios y el contendido de metales pesados en la FORSU no han influido en la desintegración de las bolsas de estudio. En cambio, se ha detectado una influencia estadísticamente significativa entre el contenido de materia orgánica total y de nutrientes de la FORSU y el porcentaje de desintegración de las muestras. No se detectado una relación estadísticamente significativa entre la presencia de bolsas de estudio en las concentraciones definidas, y la calidad del MB, medido mediante el análisis físico-químico, microbiológico y el IG del MB. La concentración de los metales pesados en la mayoría de las muestras de material bioestabilizado cumplió con los límites establecidos para la categoría A, aplicable al “compost” procedente de la fracción orgánica recogida de forma separada según el RD 506/2013 de productos fertilizantes. También se detectó fitotoxicidad alta (FA) según la metodología y criterios de valoración definidos. Esta fitotoxicidad no está relacionada con la presencia de las bolsas de estudio sino con la calidad de la FORSU de partida y/o con los productos liberados durante el proceso de compostaje. ABSTRACT The main objective of this thesis is to verify that the copolyester (PBAT) starch based (UNE 13432: 2001) biodegradable bags reach levels of degradation and disintegration required for it´s certification (% D = ≥ 90%), measured in terms of real industrial composting. The tests were performed at two municipal solid waste (MSW) treatment plants, where the most common composting techniques applied at European and national level were represented, windrow and tunnel. Two types of tests were carried out: First, a laboratory scale test (ISO 14855), as an indicator of the polymer biodegradation of the commercialized bag format. Second, a battery of tests was conducted at two MSW composting plants, Waste Treatment Center of Torija (Guadalajara), that makes compost by turned pile, and the Waste Treatment Center of Arenas de San Pedro (Ávila), where makes compost by static tunnel. To obtain the results, the parameters such as the biodegradation percentage (% B), the disintegration percentage (% D), surface degradation of the samples, the initial quality of FORSU (characterizations and physico-chemical analysis) and bioestabilithated material (MB) quality (physico-chemical analysis and IG) have been compared. In reference to the general aim It shows that the copolyester starch based certified (UNE-EN 13432) bags have reached 94.37% ± 0.007% of disintegration in the composting turned pile; and 86.36% ± 0.151% in the static tunnel. Despite the apparent difference, the result of the analysis concludes that there are no statistically significant differences between composting techniques. The presence of non-compostable materials and the heavy metals content in the FORSU has not affected in the disintegration of the bags. Instead, It has been detected a statistically significant influence over the total organic matter content and nutrient content in the FORSU and the samples disintegration percentage. A statistically significant relationship between the bag presence in the defined concentrations and the quality of MB measured by physical-chemical analysis, microbiological analysis and IG of the MB is not detected. The concentration of heavy metals in most MB samples was within the limits of A-Class, applicable to "compost" from organic waste collected separately according to RD 506/2013 of fertilizers. High phytotoxicity (FA) was also detected according to the methodology and evaluation defined. The phytotoxicity is not related to the presence of bags but it is with the FORSU initial quality and/or with the products released during the composting process.

Compostabilidad de envases de bolsas de PBAT+PLA y envases rígidos de PLA mediante tecnologías de pila y túnel

Los polímeros compostables suponen en torno al 30% de los bioplásticos destinados a envasado, siendo a su vez esta aplicación el principal destino de la producción de este tipo de materiales que, en el año 2013, superó 1,6 millones de toneladas. La presente tesis aborda la biodegradación de los residuos de envases domésticos compostables en medio aerobio para dos tipos de formato y materiales, envase rígido de PLA (Clase I) y dos tipos de bolsas de PBAT+PLA (Clases II y III). Sobre esta materia se han realizado diversos estudios en escala de laboratorio pero para otro tipo de envases y biopolímeros y bajo condiciones controladas del compost con alguna proyección particularizada en plantas. La presente tesis da un paso más e investiga el comportamiento real de los envases plásticos compostables en la práctica del compostaje en tecnologías de pila y túnel, tanto a escala piloto como industrial, dentro del procedimiento y con las condiciones ambientales de instalaciones concretas. Para ello, con el método seguido, se han analizado los requisitos básicos que debe cumplir un envase compostable, según la norma UNE – EN 13432, evaluando el porcentaje de biodegradación de los envases objeto de estudio, en función de la pérdida de peso seco tras el proceso de compostaje, y la calidad del compost obtenido, mediante análisis físico-químico y de fitotoxicidad para comprobar que los materiales de estudio no aportan toxicidad. En cuanto a los niveles de biodegrabilidad, los resultados permiten concluir que los envases de Clase I se compostan adecuadamente en ambas tecnologías y que no requieren de unas condiciones de proceso muy exigentes para alcanzar niveles de biodegradación del 100%. En relación a los envases de Clase II, se puede asumir que se trata de un material que se composta adecuadamente en pila y túnel industrial pero que requiere de condiciones exigentes para alcanzar niveles de biodegradación del 100% al afectarle de forma clara la ubicación de las muestras en la masa a compostar, especialmente en el caso de la tecnología de túnel. Mientras el 90% de las muestras alcanza el 100% de biodegradación en pila industrial, tan sólo el 50% lo consigue en la tecnología de túnel a la misma escala. En cuanto a los envases de Clase III, se puede afirmar que es un material que se composta adecuadamente en túnel industrial pero que requiere de condiciones de cierta exigencia para alcanzar niveles de biodegradación del 100% al poderle afectar la ubicación de las muestras en la masa a compostar. El 75% de las muestras ensayadas en túnel a escala industrial alcanzan el 100% de biodegradación y, aunque no se ha ensayado este tipo de envase en la tecnología de pila al no disponer de muestras, cabe pensar que los resultados de biodegrabilidad que hubiera podido alcanzar habrían sido, como mínimo, los obtenidos para los envases de Clase II, al tratarse de materiales muy similares en composición. Por último, se concluye que la tecnología de pila es más adecuada para conseguir niveles de biodegradación superiores en los envases tipo bolsa de PBAT+PLA. Los resultados obtenidos permiten también sacar en conclusión que, en el diseño de instalaciones de compostaje para el tratamiento de la fracción orgánica recogida selectivamente, sería conveniente realizar una recirculación del rechazo del afino del material compostado para aumentar la probabilidad de someter este tipo de materiales a las condiciones ambientales adecuadas. Si además se realiza un triturado del residuo a la entrada del proceso, también se aumentaría la superficie específica a entrar en contacto con la masa de materia orgánica y por tanto se favorecerían las condiciones de biodegradación. En cuanto a la calidad del compost obtenido en los ensayos, los resultados de los análisis físico – químicos y de fitotoxicidad revelan que los niveles de concentración de microorganismo patógenos y de metales pesados superan, en la práctica totalidad de las muestras, los niveles máximos permitidos en la legislación vigente aplicable a productos fertilizantes elaborados con residuos. Mediante el análisis de la composición de los envases ensayados se constata que la causa de esta contaminación reside en la materia orgánica utilizada para compostar en los ensayos, procedente del residuo de origen doméstico de la denominada “fracción resto”. Esta conclusión confirma la necesidad de realizar una recogida selectiva de la fracción orgánica en origen, existiendo estudios que evidencian la mejora de la calidad del residuo recogido en la denominada “fracción orgánica recogida selectivamente” (FORM). Compostable polymers are approximately 30% of bioplastics used for packaging, being this application, at same time, the main destination for the production of such materials exceeded 1.6 million tonnes in 2013. This thesis deals with the biodegradation of household packaging waste compostable in aerobic medium for two format types and materials, rigid container made of PLA (Class I) and two types of bags made of PBAT + PLA (Classes II and III). There are several studies developed about this issue at laboratory scale but for other kinds of packaging and biopolymers and under composting controlled conditions with some specifically plants projection. This thesis goes one step further and researches the real behaviour of compostable plastic packaging in the composting practice in pile and tunnel technologies, both at pilot and industrial scale, within the procedure and environmental conditions of concrete devices. Therefore, with a followed method, basic requirements fulfilment for compostable packaging have been analysed according to UNE-EN 13432 standard. It has been assessed the biodegradability percentage of the packaging studied, based on loss dry weight after the composting process, and the quality of the compost obtained, based on physical-chemical analysis to check no toxicity provided by the studied materials. Regarding biodegradability levels, results allow to conclude that Class I packaging are composted properly in both technologies and do not require high exigent process conditions for achieving 100% biodegradability levels. Related to Class II packaging, it can be assumed that it is a material that composts properly in pile and tunnel at industrial scale but requires exigent conditions for achieving 100% biodegradability levels for being clearly affected by sample location in the composting mass, especially in tunnel technology case. While 90% of the samples reach 100% of biodegradation in pile at industrial scale, only 50% achieve it in tunnel technology at the same scale. Regarding Class III packaging, it can be said that it is a material properly composted in tunnel at industrial scale but requires certain exigent conditions for reaching 100% biodegradation levels for being possibly affected by sample location in the composting mass. The 75% of the samples tested in tunnel at industrial scale reaches 100% biodegradation. Although this kind of packaging has not been tested on pile technology due to unavailability of samples, it is judged that biodegradability results that could be reached would have been, at least, the same obtained for Class II packaging, as they are very similar materials in composition. Finally, it is concluded that pile technology is more suitable for achieving highest biodegradation levels in bag packaging type of PBAT+PLA. Additionally, the obtained results conclude that, in the designing of composting devices for treatment of organic fraction selectively collected, it would be recommended a recirculation of the refining refuse of composted material in order to increase the probability of such materials to expose to proper environmental conditions. If the waste is grinded before entering the process, the specific surface in contact with organic material would also be increased and therefore biodegradation conditions would be more favourable. Regarding quality of the compost obtained in the tests, physical-chemical and phytotoxicity analysis results reveal that pathogen microorganism and heavy metals concentrations exceed, in most of the samples, the maximum allowed levels by current legislation for fertilizers obtained from wastes. Composition analysis of tested packaging verifies that the reason for this contamination is the organic material used for composting tests, comes from the household waste called “rest fraction”. This conclusion confirms the need of a selective collection of organic fraction in the origin, as existing studies show the quality improvement of the waste collected in the so-called “organic fraction selectively collected” (FORM).

Dinâmica do fósforo no solo em função da adição de ácidos orgânicos de baixa massa molar

A baixa eficiência da adubação fosfatada em solos altamente intemperizados é devido, entre outros fatores, à adsorção do fósforo (P) à superfície das argilas silicatadas do tipo 1:1 e, principalmente, dos (hidr)óxidos de Fe e de Al. Manejos do solo que induzem a solubilização de formas de P indisponíveis para as plantas têm sido intensamente estudados nos últimos anos. Uma tentativa de aumentar a concentração de P disponível na solução do solo para sua absorção pelas plantas é a mobilização de P por ânions de ácidos orgânicos de baixa massa molar (AOBMM). Ânions derivados de AOBMM exsudados pelas raízes de plantas ou excretados por microrganismos são associados com algumas condições de rizosfera como deficiência de P e fitotoxidez de Al e interagem com o solo de forma a aumentar a biodisponibilidade de P. Dependendo dos atributos do solo, do grau de dissociação, das propriedades e do número de grupos carboxílicos dos ânions orgânicos, o P pode ser mobilizado do solo principalmente devido à dissolução complexométrica de minerais e à adsorção competitiva dos grupos funcionais carboxílicos e fosfato nos sítios de superfície coloidais. A capacidade dos ânions citrato, malato e oxalato em mobilizar P de amostras de um Neossolo Quartzarênico típico (RQ) e de um Latossolo Vermelho ácrico (LVwf) foi avaliada por meio de um estudo de lixiviação de ânions em colunas. Devido a não detecção de P nos efluentes das colunas com LVwf, foi realizado outro estudo em colunas, no qual somente citrato foi lixiviado, mas num volume maior, e as alterações das formas de P nas amostras desse solo induzidas pela lixiviação de citrato foram identificadas por espectroscopia de absorção de raios-X na borda K do fósforo (X-ray absorption near edge structure -XANES - spectroscopy). A capacidade dos ânions de AOBMM em solubilizar P foi mais dependente do teor de P disponível e de outros atributos do solo que do número de grupos funcionais carboxílicos dos ânions orgânicos. Somente o oxalato mobilizou P do RQ, enquanto todos os ânions de AOBMM foram capazes de mobilizar P do LVwf. Quando baixos volumes de solução contendo ânions de AOBMM foram lixiviados no solo, além do aumento do pH, a mobilização de P foi acompanhada pela mobilização de Al no RQ (pH água = 5), e pela mobilização de Ca no LVwf (pH água = 5.6), o que indica solubilização de P pela complexação de Al, Ca, ou Fe, de fosfatos insolúveis, ou pela inibição da precipitação de P com esses metais. Ao lixiviar um volume maior de citrato no LVwf, o P também não foi detectado nos efluentes das colunas, mas houve lixiviação intensa de Al e Fe, bem como mudanças nas proporções de formas de P no solo caracterizadas pelos espectros XANES. Embora tenhamos encontrado indícios da ação dos principais mecanismos de solubilização de P (dissolução complexométrica de minerais e troca de ligantes entre grupos funcionais carboxílicos e P adsorvido ao solo), os ânions de AOBMM mostraram pouco potencial de efetivamente aumentar a biodisponibilidade de P.

Localization and movement of mineral oil in plants by fluorescence and confocal microscopy

Fluorescence and confocal laser scanning microscopy were explored to investigate the movement and localization of mineral oils in citrus. In a laboratory experiment, fluorescence microscopy observation indicated that when a 'narrow' distillation fraction of an nC23 horticultural mineral oil was applied to adaxial and opposing abaxial leaf surfaces of potted orange [Citrus x aurantium L. (Sapindales: Rutaceae)] trees, oil penetrated steadily into treated leaves and, subsequently, moved to untreated petioles of the leaves and adjacent untreated stems. In another experiment, confocal laser scanning microscopy was used to visualize the penetration into, and the subsequent cellular distribution of, an nC24 agricultural mineral oil in C. trifoliata L. seedlings. Oil droplets penetrated or diffused into plants via both stomata and the cuticle of leaves and stems, and then moved within intercellular spaces and into various cells including phloem and xylem. Oil accumulated in droplets in intercellular spaces and within cells near the cell membrane. Oil entered cells without visibly damaging membranes or causing cell death. In a field experiment with mature orange trees, droplets of an nC23 horticultural mineral oil were observed, by fluorescence microscopy, in phloem sieve elements in spring flush growth produced 4-5 months and 16-17 months after the trees were sprayed with oil. These results suggest that movement of mineral oil in plants is both apoplastic via intercellular spaces and symplastic via plasmodesmata. The putative pattern of the translocation of mineral oil in plants and its relevance to oil-induced chronic phytotoxicity are discussed.

Noninvasive localization of petroleum-derived spray oil in plants with chemical shift selective magnetic resonance imaging

Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) were used to detect petroleum-derived spray oils (PDSOs) in citrus seedlings and trees. The NMR spectrum of the phantom containing 10% (v/v) of a nC24 agricultural mineral oil (AMO) showed the resonance of the water protons at delta = 5 ppm, while the resonance of the oil protons at delta = 1.3 to 1.7 ppm. The peak resolution and the chemical shift difference of more than 3.3 ppm between water and oil protons effectively differentiated water and the oil. Chemical shift selective imaging (CSSI) was performed to localize the AMO within the stems of Citrus trifoliata L. seedlings after the application of a 4% (v/v) spray. The chemical shift selective images of the oil were acquired by excitation at delta = 1.5 ppm by averaging over 400 transients in each phase-encoding step. Oil was mainly detected in the outer cortex of stems within 10 d of spray application; some oil was also observed in the inner vascular bundle and pith of the stems at this point. CSSI was also applied to investigate the persistence of oil deposits in sprayed mature Washington navel orange (Citrus x aurantium L.) trees in an orchard. The trees were treated with either fourteen 0.25%, fourteen 0.5%, four 1.75%, or single 7% sprays of a nC23 horticultural mineral oil (HMO) 12 to 16 months before examination of plant tissues by CSSI, and were still showing symptoms of chronic phytotoxicity largely manifested as reduced yield. The oil deposits were detected in stems of sprayed flushes and unsprayed flushes produced 4 to 5 months after the last spray was applied, suggesting a potential movement of the oil via phloem and a correlation of the persistence of oil deposit in plants and the phytotoxicity. The results demonstrate that MRI is an effective method to probe the uptake and localization of PDSOs and other xenobiotics in vivo in plants noninvasively and nondestructively.

O efeito da adubação foliar na variedade de batata (Solanum tuberosum) de indústria “LADY ROSETTA”

A batata está sujeita a stresses bióticos (doenças, pragas, infestantes) e abióticos (condições climáticas, secura, excesso de água, ou fitotoxicidade provocada por herbicidas, entre outros). Os adubos foliares contendo nutrientes (macro e micronutrientes) poderão contribuir para uma melhor nutrição da planta, para além de exercer uma ação benéfica ao nível do potencial hídrico da folha e sua proteção contra os diversos inimigos bióticos. Instalou-se um ensaio em Marinhais na variedade de batata de indústria Lady Rosetta, para avaliar o efeito da adubação foliar de uma gama de adubos foliares “Humigel”, contendo, entre outros nutrientes, o enxofre e o potássio, numa situação de fitotoxidade causada pela aplicação de um herbicida. O ensaio foi instalado com um dispositivo experimental de parcelas totalmente aleatórias, com 4 repetições. Os tratamentos foram a aplicação de “Humigel” e sem aplicação (testemunha). A produção comercial nas parcelas com “Humigel” foi significativamente mais elevada (48 192 kg/ha) do que nas parcelas testemunha (43 458 kg/ha). Não se registaram diferenças significativas ao nível do número de tubérculos (comercial e total) por planta, nem ao nível dos parâmetros de qualidade (peso específico e teste de fritura).

Effects of vermicomposted spent mushroom compost on growing medium characteristics, plant growth, yield and abiotic stress tolerance

Treatment of agricultural biodegradable wastes and by-products can be carried out using composting or vermicomposting, or a combination of both treatment methods, to create a growing medium amendment suitable for horticultural use. When compared to traditional compost-maturation, vermicompost-maturation resulted in a more mature growing medium amendment i.e. lower C/N and pH, with increased nutrient content and improved plant growth response, increasing lettuce shoot fresh and dry weight by an average of 15% and 14%, respectively. Vermicomposted horse manure compost was used as a growing medium amendment for lettuce and was found to significantly increase lettuce shoot and root growth, and chlorophyll content. When used as a growing medium amendment for tomato fruit production, vermicomposted spent mushroom compost increased shoot growth and marketable yield, and reduced blossom end rot in two independent studies. Vermicompost addition to peat-based growing media increased marketable yield by an average of 21%. Vermicompost also improved tomato fruit quality parameters such as acidity and sweetness. Fruit sweetness, as measured using Brix value, was significantly increased in fruits grown with 10% or 20% vermicompost addition by 0.2 in truss one and 0.3 in truss two. Fruit acidity (% citric acid) was significantly increased in plants grown with vermicompost by an average of 0.65% in truss one and 0.68% in truss two. These changes in fruit chemical parameters resulted in a higher tomato fruit overall acceptability rating as determined by a consumer acceptance panel. When incorporated into soil, vermicomposted spent mushroom compost increased plant growth and reduced plant stress under conditions of cold stress, but not salinity or heat stress. The addition of 20% vermicompost to cold-stressed plants increased plant growth by an average of 30% and increased chlorophyll fluorescence by an average of 21%. Compared to peat-based growing medium, vermicompost had consistently higher nutrient content, pH, electrical conductivity and bulk density, and when added to a peat-based growing medium, vermicomposted spent mushroom compost altered the microbial community. Vermicompost amendment increased the microbial activity of the growing medium when incorporated initially, and this increased microbial activity was observed for up to four months after incorporation when plants were grown in it. Vermicomposting was shown to be a suitable treatment method for agricultural biodegradable wastes and by-products, with the resulting vermicompost having suitable physical, chemical and biological properties, and resulting in increased plant growth, marketable yield and yield quality, when used as an amendment in peat-based growing medium.

Potencial do óleo de Aloysia citriodora Palau no controle de fitopatógenos e na indução de resistência ao tombamento de plântulas de feijão, pepino e beterraba

The crops are affected by pests and diseases that decrease productivity. Among them are the damping off of seedlings that can occur in pre and post-emergence. In bean crops, cucumber and beet these diseases occur, being caused by various pathogens, especialy fitopathogenic fungi. Several measures are used for the controle of such diseases, among them, is the chemical seed treatment fungicides. However, society has become increasingly concerned about the quality and food and environmental contamination, generation a growting search for sensitive products to humans and the environment. The use of essential oils to control plant pathogens is an example of alternative tested by science in the search for less aggressive technologies. This study aimed to evaluate the efficiency of the use of essential oil Aloysia citriodora, in control of pathogens causing damping off in beans, cucumber and beet. This thesis was divided in four chapters, the introductory first, and the other addressing the control of Pythium sp. in beans, Sclerotinia sclerotiorum on cucumber, and Fusarium sp. on beet. The methodology consisted of four experiments in each pathosystem, with all the work done at the Federal Technological University of Parana, Campus Dois Vizinhos. In the first experiment evaluated the fungistatic and fungicidal effect of the essential oil of A. citriodora on PDA in vitro in mycelial growth of pathogens studied. In the second experiment evaluated the in vitro effect of essential oil concentrations of A. citriodora in BD medium on microscope slides, on the germination of sporangia Pythium sp. and conidia Fusarium sp., and in Petri dishes with PDA medium, the sclerotia germination speed index of S. sclerotiorum. In the third experiment, we evaluated in germination test in paper roll (PR), the phytotoxic effect or not the use of essential oil concentrations of A. citriodora in dry bean seed, cucumber and beet. The variables used to assess this experiment were the germination percentage, mediun green mass per plant and average length of seedlings. In the fourth experiment we assessed the effect of treating bean seeds, cucumber and beet with essential oil contents of A. citriodora, seeds in their subsequent substrates contamined with pathogens studied, Pythium sp., S. sclerotiorum and Fusarium sp. In this experiment we used the following variables: percentage of emergence, percentage of post-emergence damping off, green average mass per plant, average length per plant and biochemical analyzes. The biochemistry of plant tissues evaluated were as follows: protein content, enzymatic activities of peroxidases, phenylalanine ammonia-liase (PAL), chitinases and β-1,3-glucanases. The in vitro results show that the essential oil has fungistatic and fungicidal effect on mycelial growth, on sporangia germination, conidia and sclerotia of the pathogens studied in this work, wich may be related to its major components, citral and limonene. The oil also exhibits low phytotoxicity to seeds of the species studied, only in beans decreases germination in most studied dosage (0,25%), cucumber also in the higher dosage (0,25%) reduce the length of seedlings, and beet there were no negative effects to the seedlings. In the test in substrate contaminated with the pathogens, the use of essential oil: increased germination and decreased post emergence damping off of beans seedlings; at a concentration of 0,0625% decreases post emergence damping off in cucumber. In biochemical analyzes found an increase in the enzymatic activity of peroxidases and β-1,3-glucanases on beans, and glucanases on cucumber, and increased enzyme activity of peroxidases on beet, showing action in resistance induction at damping off.

Effect of different doses of post-emergence-applied iodosulfuron on weed control and grain yield of malt barley (Hordeum distichum L.), under Mediterranean conditions

A study was carried out over a two year period (2009/2010 and 2012/2013) on an experimental farm in the Alentejo region (Beja), in southern Portugal where rainfed malt barley (Hordeum distichum L.) is sown at the end of autumn or beginning of winter (November– December). The aim of this experiment was to study the efficiency of the herbicide iodosulfuron-methyl-sodium to control post-emergence broadleaved weeds in this cereal crop. The malt barley crop was established using no-till farming. This technology provides the necessary machine bearing capacity of the soil to assure the post-emergence application of herbicides at two diferente weed development stages. The herbicide iodosulfuron-methyl-sodium was applied at three doses (5.0, 7.5, and 10.0 g a. i. · ha–1) and at two different broadleaved weed development stages (3 to 4 and 6 to 7 pairs of leaves), that also corresponded to two diferente crop development stages (beginning of tillering and complete tillering). The results indicated that early herbicide application timing provided a significantly higher efficiency for all the applied herbicide doses, but this better weed control was not reflected in a higher crop grain yield. The lack of a higher crop grain yield was probably due to a crop phytotoxicity of the herbicide, when used at an early application timing.

O efeito da adubação foliar na variedade de batata (Solanum tuberosum) de indústria “LADY ROSETTA”

A batata está sujeita a stresses bióticos (doenças, pragas, infestantes) e abióticos (condições climáticas, secura, excesso de água, ou fitotoxicidade provocada por herbicidas, entre outros). Os adubos foliares contendo nutrientes (macro e micronutrientes) poderão contribuir para uma melhor nutrição da planta, para além de exercer uma ação benéfica ao nível do potencial hídrico da folha e sua proteção contra os diversos inimigos bióticos. Instalou-se um ensaio em Marinhais na variedade de batata de indústria Lady Rosetta, para avaliar o efeito da adubação foliar de uma gama de adubos foliares “Humigel”, contendo, entre outros nutrientes, o enxofre e o potássio, numa situação de fitotoxidade causada pela aplicação de um herbicida. O ensaio foi instalado com um dispositivo experimental de parcelas totalmente aleatórias, com 4 repetições. Os tratamentos foram a aplicação de “Humigel” e sem aplicação (testemunha). A produção comercial nas parcelas com “Humigel” foi significativamente mais elevada (48 192 kg/ha) do que nas parcelas testemunha (43 458 kg/ha). Não se registaram diferenças significativas ao nível do número de tubérculos (comercial e total) por planta, nem ao nível dos parâmetros de qualidade (peso específico e teste de fritura).