Publication: Formulación de nuevos productos bioestimulantes con extractos de algas para cultivos hortícolas regados con aguas no convencionales
Authors
Navarro Pérez, Valeria
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Escuela Internacional de Doctorado
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García Sánchez, Francisco ; Simón Grao, Silvia ; Alfosea Simón, Marina
Publisher
Universidad de Murcia
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DOI
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info:eu-repo/semantics/doctoralThesis
Description
Abstract
La agricultura se enfrenta a desafíos como la escasez de recursos hídricos, que afectan al rendimiento y a la calidad de los cultivos. En zonas áridas y semiáridas, la elevada concentración de boro en el agua de riego, asociada al uso de aguas regeneradas o desaladas, constituye uno de los principales problemas, ya que su acumulación altera procesos fisiológicos y metabólicos que limitan el desarrollo vegetal. El tomate (Solanum lycopersicum L.) es uno de los cultivos hortícolas que puede ver comprometido su crecimiento, producción y calidad bajo condiciones de toxicidad por boro. En este contexto, los bioestimulantes basados en extractos de algas han despertado un creciente interés por su contenido en compuestos bioactivos y su potencial para mejorar la respuesta de los cultivos frente al estrés y favorecer una producción más sostenible.
Esta tesis doctoral se ha centrado en la caracterización bioquímica de diferentes especies de algas, como macroalgas, microalgas, diatomeas y cianobacterias, y en la evaluación de la actividad bioestimulante de algunos de sus extractos en plantas de tomate cultivadas bajo condiciones de toxicidad por boro (15 mg L-1).
En el Capítulo 3 se caracterizó la composición bioquímica de la biomasa algal de 11 especies de macroalgas, analizando su perfil nutricional, hormonal y metabolómico, junto con otros compuestos asociados a su actividad biológica. Ascophyllum nodosum y Undaria pinnatifida destacaron por su elevada diversidad y concentración de metabolitos. Laminaria digitata presentó un alto contenido de manitol, y Palmaria palmata mostró niveles elevados de nitratos y betaínas. Las algas verdes presentaron concentraciones altas de magnesio, amonio y nitrógeno total, destacando Ulva rigida por su contenido de asparagina. Todas las especies contenían niveles elevados de hormonas vegetales.
De forma similar, en el Capítulo 4 se analizó la biomasa de 4 microalgas, 2 diatomeas y una cianobacteria, evaluando su composición bioquímica, perfil de metabolitos y contenido nutricional. Phaeodactylum tricornutum y Skeletonema sp. mostraron la mayor diversidad de compuestos bioactivos. Isochrysis sp. y Phaeodactylum tricornutum presentaron las concentraciones más elevadas de distintos metabolitos. Haematococcus pluvialis destacó por su contenido en auxinas y giberelinas, Nannochloropsis gaditana por su concentración de prolina y betaína, Arthrospira platensis por su alto nivel de acetato y Chlorella vulgaris por su contenido de sacarosa y xilosa.
Por otro lado, en el Capítulo 5 se estudió el efecto de una elevada concentración de boro (15 mg L-1) en plantas de tomate y la aplicación de extractos de Laminaria digitata y Phaeodactylum tricornutum, solos o combinados con metaloides y micronutrientes. Se evaluaron parámetros fisiológicos, bioquímicos y metabólicos. Los tratamientos mejoraron la estabilidad fisiológica y metabólica de las plantas, aunque no redujeron la acumulación de boro. El análisis de componentes principales mostró que la tolerancia relativa estuvo relacionada principalmente con variables fisiológicas y metabólicas. Entre los tratamientos aplicados, el extracto de Laminaria digitata fue el más eficaz.
Por último, en el Capítulo 6 se evaluaron las respuestas agronómicas, nutricionales y metabólicas de las plantas de tomate al riego con una elevada concentración de boro (15 mg L-1) y la aplicación foliar de productos bioestimulantes formulados con un extracto de Laminaria digitata. La toxicidad por boro redujo la producción total, al disminuir el peso medio del fruto y afectar al calibre y la firmeza, sin modificar el número de frutos ni la calidad química. Aunque los bioestimulantes modificaron el estado nutricional y el perfil metabolómico, estas respuestas no fueron suficientes para mitigar la toxicidad ni mejorar el rendimiento.
En conjunto, esta tesis aporta información detallada sobre la composición bioquímica de distintas especies de algas y su potencial como bioestimulantes, así como sobre la respuesta fisiológica, nutricional y metabólica del tomate al exceso de boro.
Agriculture faces challenges such as water scarcity, which affect crop performance and quality. In arid and semi-arid regions, the high concentration of boron in irrigation water, associated with the use of reclaimed or desalinated water, represents one of the main problems, as its accumulation alters physiological and metabolic processes that limit plant development. Tomato (Solanum lycopersicum L.) is one of the horticultural crops whose growth, yield and quality can be compromised under boron toxicity. In this context, algal-based biostimulants have gained increasing interest due to their content of bioactive compounds and their potential to enhance crop responses to stress and promote more sustainable production. This doctoral thesis focuses on the biochemical characterization of different algal species, including macroalgae, microalgae, diatoms and cyanobacteria, and on the evaluation of the biostimulant activity of some of their extracts in tomato plants grown under boron toxicity (15 mg L-1). In Chapter 3, the biochemical composition of the algal biomass of 11 macroalgal species was characterised by analysing their nutritional, hormonal and metabolomic profiles, together with other compounds associated with their biological activity. Ascophyllum nodosum and Undaria pinnatifida showed high diversity and concentration of metabolites. Laminaria digitata exhibited a high mannitol content, and Palmaria palmata showed elevated levels of nitrates and betaines. Green algae presented high concentrations of magnesium, ammonium and total nitrogen, with Ulva rigida standing out for its asparagine content. All species contained high levels of plant hormones. Similarly, Chapter 4 analysed the biomass of 4 microalgae, 2 diatoms and one cyanobacterium, evaluating their biochemical composition, metabolite profile and nutritional content. Phaeodactylum tricornutum and Skeletonema sp. showed the greatest diversity of bioactive compounds. Isochrysis sp. and Phaeodactylum tricornutum presented the highest concentrations of several metabolites. Haematococcus pluvialis stood out for its auxin and gibberellin content, Nannochloropsis gaditana for its high levels of proline and betaine, Arthrospira platensis for its high acetate content, and Chlorella vulgaris for its sucrose and xylose content. In Chapter 5, the effect of a high boron concentration (15 mg L-1) on tomato plants and the application of extracts of Laminaria digitata and Phaeodactylum tricornutum, alone or combined with metalloids and micronutrients, was studied. Physiological, biochemical and metabolic parameters were evaluated. The treatments improved the physiological and metabolic stability of the plants, although they did not reduce boron accumulation. Principal component analysis showed that tolerance was mainly associated with physiological and metabolic variables. Among the applied treatments, the extract of Laminaria digitata was the most effective. Finally, Chapter 6 evaluated the agronomic, nutritional and metabolic responses of tomato plants to irrigation with a high concentration of boron (15 mg L-1) and the foliar application of biostimulant products formulated with an extract of Laminaria digitata. Boron toxicity reduced total yield by decreasing fruit weight and affecting fruit size and firmness, without altering the number of fruits or chemical quality. Although the biostimulants modified the nutritional status and metabolomic profile, these responses were not sufficient to mitigate toxicity or improve yield. Overall, this thesis provides detailed information on the biochemical composition of different algal species and their potential as biostimulants, as well as on the physiological, nutritional and metabolic responses of tomato to excess boron
Agriculture faces challenges such as water scarcity, which affect crop performance and quality. In arid and semi-arid regions, the high concentration of boron in irrigation water, associated with the use of reclaimed or desalinated water, represents one of the main problems, as its accumulation alters physiological and metabolic processes that limit plant development. Tomato (Solanum lycopersicum L.) is one of the horticultural crops whose growth, yield and quality can be compromised under boron toxicity. In this context, algal-based biostimulants have gained increasing interest due to their content of bioactive compounds and their potential to enhance crop responses to stress and promote more sustainable production. This doctoral thesis focuses on the biochemical characterization of different algal species, including macroalgae, microalgae, diatoms and cyanobacteria, and on the evaluation of the biostimulant activity of some of their extracts in tomato plants grown under boron toxicity (15 mg L-1). In Chapter 3, the biochemical composition of the algal biomass of 11 macroalgal species was characterised by analysing their nutritional, hormonal and metabolomic profiles, together with other compounds associated with their biological activity. Ascophyllum nodosum and Undaria pinnatifida showed high diversity and concentration of metabolites. Laminaria digitata exhibited a high mannitol content, and Palmaria palmata showed elevated levels of nitrates and betaines. Green algae presented high concentrations of magnesium, ammonium and total nitrogen, with Ulva rigida standing out for its asparagine content. All species contained high levels of plant hormones. Similarly, Chapter 4 analysed the biomass of 4 microalgae, 2 diatoms and one cyanobacterium, evaluating their biochemical composition, metabolite profile and nutritional content. Phaeodactylum tricornutum and Skeletonema sp. showed the greatest diversity of bioactive compounds. Isochrysis sp. and Phaeodactylum tricornutum presented the highest concentrations of several metabolites. Haematococcus pluvialis stood out for its auxin and gibberellin content, Nannochloropsis gaditana for its high levels of proline and betaine, Arthrospira platensis for its high acetate content, and Chlorella vulgaris for its sucrose and xylose content. In Chapter 5, the effect of a high boron concentration (15 mg L-1) on tomato plants and the application of extracts of Laminaria digitata and Phaeodactylum tricornutum, alone or combined with metalloids and micronutrients, was studied. Physiological, biochemical and metabolic parameters were evaluated. The treatments improved the physiological and metabolic stability of the plants, although they did not reduce boron accumulation. Principal component analysis showed that tolerance was mainly associated with physiological and metabolic variables. Among the applied treatments, the extract of Laminaria digitata was the most effective. Finally, Chapter 6 evaluated the agronomic, nutritional and metabolic responses of tomato plants to irrigation with a high concentration of boron (15 mg L-1) and the foliar application of biostimulant products formulated with an extract of Laminaria digitata. Boron toxicity reduced total yield by decreasing fruit weight and affecting fruit size and firmness, without altering the number of fruits or chemical quality. Although the biostimulants modified the nutritional status and metabolomic profile, these responses were not sufficient to mitigate toxicity or improve yield. Overall, this thesis provides detailed information on the biochemical composition of different algal species and their potential as biostimulants, as well as on the physiological, nutritional and metabolic responses of tomato to excess boron
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