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Las sustancias húmicas como bioestimulantes de plantas bajo condiciones de estrés ambiental

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Abstract

RESUMEN. Las plantas están sometidas frecuentemente a situaciones desfavorables para su desarrollo y funcionamiento óptimos, ocasionadas por alteraciones en el medio ambiente. Este conjunto de situaciones desfavorables se conoce con el nombre de estrés medio ambiental. Los bioestimulantes constituyen sustancias, que por su acción pueden estimular el crecimiento de la planta, mejorar la absorción de nutrientes e incrementar los rendimientos en condiciones de estrés ambiental, independientemente de que contengan elementos nutrientes en su composición. Existen diversas categorías de bioestimulantes específicos, entre ellos, los hidrolizados de proteínas, extractos de algas, quitosana, ácidos húmicos y fúlvicos, hongos micorrízicos y bacterias promotoras del crecimiento. El objetivo de esta revisión es mostrar el efecto bioestimulante de la aplicación de sustancias húmicas en plantas, bajo condiciones de estrés. También se sintetizan aspectos relacionados con las sustancias húmicas como son sus características estructurales y su clasificación. Se informan resultados empleando sustancias húmicas como bioestimulantes, donde se comprueba su potencial para estimular diferentes procesos metabólicos y fisiológicos en condiciones de estrés ambiental. Se concluye que las sustancias húmicas presentan una estructura compleja variable, una multiplicidad de grupos funcionales y pequeñas moléculas heterogéneas que interactúan mediante uniones débiles, lo cual hace que exhiban una gran variedad de funciones beneficiosas entre las que se encuentra su potencial para incrementar los rendimientos y atenuar los efectos de estreses abióticos. Por tanto, constituyen una alternativa viable para evadir las consecuencias del cambio climático y emplear productos naturales y amigables con el medio ambiente. ABSTRACT. Plants are frequently subjected to unfavorable situations for their optimal development and operation caused by alterations in the environment. This set of unfavorable situations is known as environmental stress. Biostimulants are substances that by their action can stimulate the plant growth, improve the absorption of nutrients and increase yields under environmental stress conditions regardless of whether they contain nutrients in their composition. There are several categories of specific biostimulants, among them protein hydrolysates, algae extracts, chitosan, humic and fulvic acids, mycorrhizal fungi and growth promoting bacteria. The objective of this review is to inform the biostimulating effect of the application of humic substances in plants under stress conditions. It also synthesizes aspects related to humic substances such as their structural characteristics and classification. Results are shown using humic substances as biostimulants where their potential to stimulate different metabolic and physiological processes in abiotic stress conditions is demonstrated. It concludes that humic substances present a complex structure, a multiplicity of functional groups and small molecules that interact by weak junctions, which makes them exhibit a great variety of beneficial functions among which is their potential to increase the yields and attenuate the effects of abiotic stresses. Therefore they constitute a viable alternative to avoid the consequences of climate change and use natural and environmentally friendly products.

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... Los bioestimulantes, elaborados principalmente a partir de extractos vegetales, algas y otros productos naturales, mejoran la resistencia de las plantas al estrés abiótico mediante la regulación de procesos fisiológicos y morfológicos. Estas sustancias no solo favorecen la absorción de nutrientes y la calidad del cultivo, sino que también estimulan la expresión génica y la actividad metabólica de las plantas (Veobides-Amador et al., 2018). Entre los bioestimulantes más utilizados destacan los extractos de algas, ricos en metabolitos bioactivos, y el extracto de Aloe vera, que contiene fitohormonas y aminoácidos promotores del crecimiento (Espinosa-Antón et al., 2021;Salazar et al., 2023). ...
... Los bioestimulantes son sustancias o microorganismos aplicados a plantas o suelos que mejoran el crecimiento y desarrollo de los cultivos al incrementar su tolerancia al estrés biótico y abiótico, y optimizar la absorción de nutrientes y el uso del agua. Su origen puede ser natural o sintético, y pueden presentarse en diversas formas (líquidos, polvos o gránulos), contribuyendo a reducir la dependencia de fertilizantes y pesticidas químicos, y minimizando el impacto ambiental en la agricultura(Veobides-Amador et al., 2018; du Jardín, 2015).Derivados de Aloe vera y macroalgas como Ascophyllum nodosum han demostrado ser especialmente eficaces al promover la fotosíntesis y la adaptación a condiciones de estrés. Además, contribuyen a la sostenibilidad agrícola al reducir la necesidad de insumos químicos y mejorar la calidad del suelo(Veobides-Amador et al., 2018;Espinosa-Antón et al., 2021). ...
... Su origen puede ser natural o sintético, y pueden presentarse en diversas formas (líquidos, polvos o gránulos), contribuyendo a reducir la dependencia de fertilizantes y pesticidas químicos, y minimizando el impacto ambiental en la agricultura(Veobides-Amador et al., 2018; du Jardín, 2015).Derivados de Aloe vera y macroalgas como Ascophyllum nodosum han demostrado ser especialmente eficaces al promover la fotosíntesis y la adaptación a condiciones de estrés. Además, contribuyen a la sostenibilidad agrícola al reducir la necesidad de insumos químicos y mejorar la calidad del suelo(Veobides-Amador et al., 2018;Espinosa-Antón et al., 2021). ...
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Los bioestimulantes ayudan a mitigar los efectos negativos del estrés abiótico, facilitando la absorción de nutrientes por las plantas. Este estudio evaluó el efecto de dos bioestimulantes aplicados de forma foliar al 10%: extracto de Aloe vera y macroalgas, en el desarrollo de Raphanus sativus sometido a estrés abiótico. Se germinaron 100 semillas de rábano rojo crimson giant y se trasplantaron en un diseño experimental con cuatro tratamientos y cinco réplicas. El T1, T2, y T3 fueron sometidos a estrés abiótico, mientras que el T0 sirvió de control. El extracto de Aloe vera aplicado al T2 fue l mesófilo de la sábila mediante extracción con etanol y posterior liofilización. El bioestimulante comercial VustereQ, a base de macroalgas, fue aplicado al T3. Los resultados mostraron que tanto T2 como T3 presentaron un crecimiento similar en variables como la longitud de la planta, el diámetro del bulbo y el peso seco. Sin embargo, el T3 fue el más efectivo en el desarrollo radicular, mientras que el T2 favoreció el desarrollo foliar. Se concluye que el bioestimulante de Aloe vera es el más eficaz para estimular el crecimiento bajo condiciones de estrés hídrico, salino y térmico.
... Humic substances (HSs) are materials derived from the decomposition of plant, animal, and microbial residues and from the metabolic activity of soil microorganisms, corresponding to approximately 80% of soil organic matter (SOM), and they are also found in aquatic environments and the atmosphere [7]. These compounds are known to have biostimulant properties and are used by farmers to reduce the use of agrochemicals and more efficiently use nutrients to achieve more sustainable food production [8]. ...
... Chemically, these are fatty acids of various structures and degrees of saturation (Table 3). The content of unsaturated fatty acids with a hydrocarbon radical length of more than 10 is 13.25% (positions 5,7,9,[11][12][13][14][15], which is sufficient to ensure suspension stability. The stabilizers derived from cottonseed cake do not contain synthetic components, are biodegradable, and environmentally friendly, making them promising for companies aiming for sustainable and environmentally responsible multi-fertilizer production. ...
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The production of sugar beet in the Republic of Kazakhstan is insufficient to meet the domestic sugar needs of the population. This shortfall is attributed to the natural and climatic conditions, the high cost of production, and the low use of mineral fertilizers. The objective of the study is to investigate the impact of the organic humic fertilizer “Tumat” on the growth, development, yield, and sugar content of sugar beet in the conditions of irrigated light chestnut soils in Southeast Kazakhstan. Scientific research confirms the effectiveness of using the organic humic fertilizer Tumat for cultivating sugar beets. This fertilizer is highly bioavailable and contains a balanced mix of essential macronutrients and micronutrients, polyunsaturated fatty acids, and other biologically active substances. Foliar feeding of sugar beets enriches the soil with exchangeable potassium, mobile phosphorus, and easily hydrolyzable nitrogen during the plant’s vegetative period. Using the Tumat fertilizer enhances plant germination rates by 6.0–16.0%, stimulates growth and development, accelerates the ripening of sugar beets, and increases the yield of tubers by 10.5–15.2%, sugar content by 0.4–0.7%, and sugar output by 13.6–20.8%. An organic humic fertilizer, is recommended as an environmentally safe and effective agricultural product that boosts the productivity and quality of sugar beets, as well as soil fertility.
... Sus efectos han sido reportados en numerosos estudios y pueden ser directos o indirectos (Canellas & Olivares, 2014;Canellas et al., 2015). Los directos se relacionan con procesos metabólicos y fisiológicos y modifican el desarrollo o la organización de la raíz y la absorción de nutrientes (Trevisan et al., 2010, Barros Dobbs et al., 2010, mientras que los indirectos se asocian a propiedades físicas, químicas y biológicas del suelo e influyen en la fertilidad (al facilitar la absorción de nutrientes y aumentarla a nivel radicular), en el suministro de nutrientes, en la retención de humedad y en otros aspectos (figura 36) (Veobides Amador et al., 2018). Estos efectos positivos se reflejan posteriormente en la fisiología de las plantas y la producción del cultivo . ...
... Estos efectos parecen estar relacionados con cambios en la forma, el tamaño y la estructura de las raíces más profundas (Canellas et al., 2015). En ese sentido, las interacciones sh-planta alteran la tasa de degradación o transformación de los minerales, generan cambios en el pH y liberan agentes que forman complejos con metales y otros nutrientes poco accesibles en el suelo (Veobides Amador et al., 2018). ...
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Colombia un país megadiverso, refiere de igual manera una ingente heterogeneidad y complejidad en las comunidades que en ella habitan; especialmente en los territorios de la periferia confluyen la biodiversidad y la riqueza etnocultural de los pueblos ancestrales. El alcance de la paz total como compromiso del país requiere la integración de estos saberes ancestrales a los procesos de generación de nuevo conocimiento a partir de un acercamiento divergente respecto a los procesos tradicionales de extensión agropecuaria. Al respecto, Agrosavia contribuye a las iniciativas del gobierno nacional para la transformación social y productiva del país a través de los lineamientos de una metodología híbrida para la vinculación científico-tecnológica de los pueblos ancestrales de Colombia como planteamiento para el alcance de procesos de gestión del conocimiento interculturales. El presente documento constituye la materialización de los mencionados lineamientos donde se propone una salida frente la tensión entre la conservación biocultural y la producción de alimentos, donde la innovación tecnológica se direcciona al cumplimiento de los objetivos autónomos del pueblo Kankuamo y, el fortalecimiento de sus procesos etnoeducativos en concordancia con su visión de desarrollo comunitario indígena.
... Thus, HA with high molecular weight have a greater impact on the physical properties and local biological effects of the soil, whereas low molecular weight FA influences in the transport of micronutrients in soil solution. In addition, they also exert biological effects in the rhizosphere [9]. ...
... The role of HA in agricultural soils is well established, especially in those soils with low organic matter, and also too in pollution remediation [9]. HA has long been used in improvement crop productivity and soil fertility. ...
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At present there is a great advance in the use of organic substances as fertilizers; humic substances are one of them with various forms of extraction. This article evaluates the extraction yield of humic substances (humic acid and fulvic acid) from three raw materials and different basic extractants and acids. In the basic extraction of humic substances, the type of raw material significantly influences, to a p value equal to 5 %. The maximum extraction volumes of humic substances are with garden waste. The fractionation stage of the humic and fulvic acids (acid extraction) depends on the type of basic extractant. The alternative Vermicompost - NaOH - HCl is the most economic and technically feasible, with 38.53 % of extraction yield value of humic acid and 64.90 $/h of gross profit.
... Además del papel que tienen los AH en las propiedades del suelo y en la descontaminación, por si mismos, de medios acuáticos y terrestres, como se describió anteriormente, también tienen efectos bioactivos sobre las plantas. Así, regulan la actividad celular, promueven el metabolismo, actúan como análogos de hormonas como las auxinas, citoquininas y giberelinas, lo cual se traduce en el desarrollo de respuestas fisiológicas que conducen al favorecimiento del crecimiento , desarrollo, producción de biomasa y rendimiento vegetal (Jannin et al., 2012;Veobides et al., 2018;Seguel et al., 2019;Zou et al., 2021). ...
... En este aspecto, la fracción de AH se caracteriza por su efecto bioestimulante, biofertilizante y biorregulador, por lo cual influyen positivamente en el desempeño de las plantas (Alarcón et al., 2018). A través del efecto biofertilizante mejoran la absorción de macronutrientes y micronutrientes, a través del efecto bioestimulante aumentan el crecimiento de raíces y atenúan el efecto del estrés abiótico cuando las plantas se desempeñan bajo condiciones adversas, y a través del efecto biorregulador regulan positivamente el metabolismo Veobides et al., 2018). ...
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RESUMEN Los ácidos húmicos son una fracción de la materia orgánica humificada con efectos bioactivos que influyen en la fisiología de las plantas, promueven el desarrollo del sistema radical, estimulan el metabolismo primario y secundario, promueven la fotosíntesis, la respiración celular y mejoran la respuesta de las plantas frente a condiciones de estrés; por lo anterior han sido ampliamente estudiados como agentes bioestimulantes, principalmente en plantas de interés agrícola. Sin embargo, no se han explorado opciones de bioestimulación de plantas con otros propósitos, por ejemplo la fitorremediación. El objetivo de esta revisión es analizar evidencias científicas para proponer la bioestimulación con ácidos húmicos como una estrategia para aumentar la remoción de contaminantes a través de plantas fitorremediadoras. En este documento se relacionan aspectos de la estructura y bioactividad de los ácidos húmicos, los conceptos de fitorremediación y bioestimulación, y se analiza como el efecto bioactivo de los ácidos húmicos sobre las plantas podría influir en las diferentes estrategias de fitorremediación. La información analizada permite concluir que los AH se podrían utilizar como pre acondicionadores de plantas que serán utilizadas para la remoción de contaminantes en agua y suelo, a través de fitorremediación, lo cual se puede convertir en una estrategia biotecnológica promisoria para coadyuvar en procesos de tratamiento de ambientes contaminados. Palabras clave: sustancias húmicas; biorremediación; contaminación ambiental. _____________________________________________________________________________________ ABSTRACT Humic acids are a humified organic matter fraction that exhibit bioactive effets, which influence plant physiology, enhance root system development, stimulate primry and secondary metabolism, promote photosynthesis, cellular respiration and improve plant responses uder stress coditions; therefore, they have been widely studied as biostimulant agents, mainly in plants of agricultural interest. However, plant biostimulation options for other purposes, for example phytoremediation, have not been explored. The objective of this review is to analyze scientific evidence that leads to propose biostimulation with humic acids as a strategy to increase the removal of contaminants through phytoremediation plants. This document relates aspects of the structure and bioactivity of humic acids, the concepts of phytoremediation and biostimulation, and analyzes how the bioactive effect of humic acids on plants could influence the different phytoremediation strategies. The information analyzed can conclude that the AH will be used as plant pre-conditioners that will be used for removal contaminants in water and soil through phytoremediation, which can become a promising biotechnological strategy to assist in treatment processes of contaminated environments.
... La importancia del estudio y del manejo de las sustancias húmicas radica en la gran influencia de la industria, sobre todo en la agricultura ayudando al crecimiento y desarrollo de los cultivos (Bezuglova & Klimenko, 2022;Nsengumuremyi et al., 2022). Los impactos secundarios abordan el papel de las sustancias húmicas en la mejora de la fertilidad del suelo, centrándose particularmente en sus efectos sobre los aspectos físicos, químicos y biológicos del mismo (Nardi et al., 2021;Veobides-Amado et al., 2018). No obstante, la agricultura no es el único ámbito de aplicación de las sustancias húmicas (Ramos-Ruíz, 2000), sino que cuenta con otros usos entre los que destacan la medicina y productos farmacéuticos, dispersante de polvos cerámicos, síntesis de materiales, así como en la industria cosmética como protector solar (Hriciková et al., 2023;Kapil et al., 2023). ...
... El uso de enmiendas orgánicas ha ayudado a mitigar los daños ocasionados por factores abióticos, además, que suelen potencializar el rendimiento en diversos cultivos. Por tal motivo, Veobides-Amador et al. (2018) indican que el uso de sustancias húmicas tiene efectos directos sobre las características físicas, fisicoquímicas y biológicas del suelo, al aumentar la retención de humedad, el aporte de nutrientes, la proliferación de los microorganismos benéficos y en la formación de complejos iónicos como el fierro y el zinc. Por lo anteriormente, el objetivo fue evaluar el uso de fertilizantes químicos, orgánicos y su combinación sobre el efecto en la morfología, calidad de fruto y rendimiento del cultivo de tomate de cáscara (P. ...
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The use of conventional fertilizers has been a viable production alternative for many years; however, it has caused serious damage to ecosystems. The objective of the present study was to evaluate the effect of chemical, organic and chemical-organic fertilization on morphology, fruit quality and yield of husk tomato under rainfed conditions. The experiment was carried out in completely randomized blocks with four treatments and three repetitions: T1 = 120N-80P-120K, T2 = 3.479 kg m2 of vermicompost, T3 = 120N-80P-120K + 3.479 kg m2 of vermicompost and T4 = witness. The results indicate that treatment 3 (chemical-organic) positively influenced the variables of morphology, yield and pH. The chemical-organic treatment obtained the best results for yield, while the content of total soluble solids did not present a significant difference between treatments. The use of chemical organic fertilization is a production alternative that has a positive effect on the nutrition of shell tomato
... When the ON content has humic and fulvic acids, consider the following: humic substances are absorbed through plant tissue, raising the amino acid content, nutrients, and vitamins. The indirect effect includes the improvement of the soil's chemical, physical, and biological properties through water and nutrient retention, ventilation, permeability, greater CEC, root development; also, the direct effects include stimulates biomass accumulation, facilitates mineral nutrient absorption, and increases the resistance of plants to environmental stress [22][23][24][25][26][27]. ...
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Research on medicinal plants is essential for their conservation, propagation, resistance to environmental stress, and domestication. The use of organic nutrition has been demonstrated to improve soil fertility and plant quality. It is also important to study the effects of the Basic Cation Saturation Ratio (BCSR) approach, which is a topic where there is currently controversy and limited scientific information. Evaluating the growth and yields of Agastache mexicana subsp. mexicana (Amm) in different environments is crucial for developing effective propagation and domestication strategies. This includes examining warm and subhumid environments with rain in summer in comparison to mild environments with summer rain. Significant differences were observed in the effects of cold, waterlogging, and heat stresses on the plant’s biomass yield and the morphometric-quantitative modeling by means of isolines. The biomass yield was 56% higher in environment one compared to environment two, 19% higher in environment one with organic nutrition, and 48% higher in environment two with organic nutrition compared to using only BCSR nutrition. In the second harvesting cycle, the plants in environment one did not survive, while the plants in environment two managed to survive without needing additional nutrition. Statistical and mathematical analyses provided information about the population or sample. Additionally, further analysis using isolines as a new approach revealed new insights into understanding phenology and growth issues.
... Las aplicaciones del quitosano se presentan en diversos campos, como la industria agrícola (bioestimulante y fungicidas), en la medicina (cicatrización de heridas, producción de suturas y cremas bactericidas) y en la industria cosmética (bactericida en jabones y champús, hidratante para la piel y pasta dental) (Romero & Pereira, 2020). Por su actividad bioestimuladora comprobada en varias plantas, relacionadas con la producción de metabolitos secundarios, reguladores del crecimiento y agentes antiestrés (Hidangmayum et al., 2019;Stasińska & Hawrylak, 2022), puede ser utilizado para reemplazar el uso de los agroquímicos (fertilizantes y fungicidas químicos), que actualmente se aplican en grandes cantidades en los cultivos y generan un impacto negativo sobre el medio ambiente (Veobides et al., 2018;Shahrajabian et al., 2021). ...
Article
En la actualidad el uso de agroquímicos es necesario para la producción de alimentos de interés agroindustrial como el tomate (Solanum lycopersicum L.). Estos se aplican principalmente como estimulantes de crecimiento para el cultivo; sin embargo, también traen consigo problemas que afectan al medio ambiente y la salud humana, por lo que se busca mejores alternativas que permitan la reducción de su uso; ante esto, el quitosano se presenta como una opción de bioestimulante en plantas. El objetivo de este trabajo de investigación fue estudiar el efecto del quitosano extraído del caparazón de Romaleon setosum (Molina, 1782) o “cangrejo peludo” en la germinación y desarrollo de plántulas de S. lycopersicum. El quitosano extraído fue aplicado a las semillas de tomate a concentraciones de 1000, 2000 y 3000 mg/l, y se evaluó el porcentaje de germinación luego de 10 días y los indicadores de crecimiento cada siete días en un periodo de tres semanas. Los resultados mostraron que las semillas tratadas con quitosano presentaron efecto estimulante en los indicadores de biomasa fresca y biomasa seca, y sobre todo en la longitud de radícula, mas no para la germinación de semillas, ni en la longitud de tallo. Mientras que, de las concentraciones aplicadas, fue la de 1000 mg/L la que presentó mejores resultados en los indicadores evaluados. En la actualidad el uso de agroquímicos es necesario para la producción de alimentos de interés agroindustrial como el tomate (Solanum lycopersicum L.). Estos se aplican principalmente como estimulantes de crecimiento para el cultivo; sin embargo, también traen consigo problemas que afectan al medio ambiente y la salud humana, por lo que se busca mejores alternativas que permitan la reducción de su uso; ante esto, el quitosano se presenta como una opción de bioestimulante en plantas. El objetivo de este trabajo de investigación fue estudiar el efecto del quitosano extraído del caparazón de Romaleon setosum (Molina, 1782) o “cangrejo peludo” en la germinación y desarrollo de plántulas de S. lycopersicum. El quitosano extraído fue aplicado a las semillas de tomate a concentraciones de 1000, 2000 y 3000 mg/l, y se evaluó el porcentaje de germinación luego de 10 días y los indicadores de crecimiento cada siete días en un periodo de tres semanas. Los resultados mostraron que las semillas tratadas con quitosano presentaron efecto estimulante en los indicadores de biomasa fresca y biomasa seca, y sobre todo en la longitud de radícula, mas no para la germinación de semillas, ni en la longitud de tallo. Mientras que, de las concentraciones aplicadas, fue la de 1000 mg/L la que presentó mejores resultados en los indicadores evaluados.
... Se ha demostrado que los compuestos húmicos, conocidos por sus efectos bioestimulantes, pueden mejorar el crecimiento y desarrollo de las plantas, incluyendo la longitud de los tallos, las raíces, las hojas, la masa fresca y seca, así como la calidad y el tamaño de los frutos. Además, se ha observado un aumento en los rendimientos de los cultivos bajo sistemas de riego por aspersión (Trevisan et al., 2010;Veobides et al., 2018). Estos bioestimulantes ofrecen una alternativa viable para mitigar los efectos adversos del cambio climático en la agricultura. ...
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The production of bananas (Musa spp.) represents the most important item for the economy of the Province of El Oro. The penetration of the root system in this crop is weak, so the distribution is related to the texture and structure of the soil. This study was to evaluate the effect of different root stimulation programs on the vegetative development of banana crops under a sprinkler irrigation system. The research work was developed in the "Adrianita" farm in the Province of El Oro - Ecuador, which is located in the localities of Sabalucal-Parish Barbones del Canton el Guabo, a completely randomized block design (DBCA) was carried out, applying six treatments, T1 (Control), T2 (Carving), T3 (Rooting based on seaweed), T4 (Humic Acids), T5 (Rooting + Humic Acids), and T6 (Herculization), divided into four blocks, the Data were statistically analyzed by analysis of variance (ANOVA), using the Agrostat® software (Barbosa and Maldonado, 2010). The results obtained were plant height 3.59 m in T6, pseudostem diameter 90.61 cm in T6, number of leaves 8.07 in T1, chlorophyll levels 52.85 (SPAD) in T6, total root mass 85.92 g in T6.
... This stimulation can be carried out in various ways, including the contribution of growth-regulating substances (Aremu et al., 2015), the increase in the regulation of genes linked to hormonal processes (Barone et al., 2019), and the improvement of the physical and chemical properties of the soil (Pant et al., 2011(Pant et al., , 2012, among others. Thus, biostimulants can improve crop tolerance to biotic and abiotic stress (Iwuagwu et al., 2022;Veobides et al., 2018). ...
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Using large volumes of synthetic chemical fertilizers is a general practice in modern agriculture at a high economic and environmental cost. Biostimulants have become an alternative to this routine due to their ability to stimulate plant physiological processes without polluting soil and water. In Ecuador, however, little research has been carried out on the effect of biostimulants on the yield of crops of agricultural interest. The objective of this research was to determine the effect of foliar application of a biostimulant based on bovine manure vermicompost (VCLB) leachates on physiological variables and the yield of corn, cotton, and peanuts under field conditions and chard and five pepper hybrids in semi-protected cultivation under the agro-climatic conditions of the province of Manabí, Ecuador. The nine experiments carried out with the species and hybrids included various dilutions of VCLB and controls consisting of fertilization with nitrogen, phosphorus, and potassium, depending on the species, and soil without fertilizer. In all species, VCLB-induced plant length, chlorophyll content, and crop yield exhibit equal or higher statistical differences than those achieved under chemical fertilization (NPK). These results demonstrate the potential of this biostimulant as a sustainable alternative to produce these crops, reducing potentially the adverse effects of production on the environment under the tropical conditions of Manabí, Ecuador. We recommend corroborating these results with production-scale research.
... At the beginning of the Krebs cycle, using (non-protein) amino acids such as citrulline (CI) (Song et al., 2020) improves nitrogen balance and eliminates hydroxyl radicals. With biostimulants such as humic substances (HS) (Veobides-Amador et al., 2018), the transport of organic and inorganic molecules and the absorption of proteins, amino acids, and ionic nutrients becomes more efficient (Popa et al., 2022). These same processes can be balanced with hormones such as gibberellin (GA) (Tuan et al., 2018) or with salicylic acid (SA). ...
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Objective: To evaluate the effect of different germination promoters on three maize genotypes grown in Dystric Cambisol soils, since germination problems are linked to latency and restrict agronomic management. Design/Methodology/Approach: We conducted an experiment at the Instituto Tecnológico Superior de Juan Rodríguez Clara using a split-plot design with a factorial treatment arrangement. The large plot contained genotypes (GEN) G1 = MS-405, G2 = Arlequin, and G3 = MS-404; while the small one comprised promoter (PROMO) HS = humic substance, CI = citrulline, and SA = salicylic acid. We evaluated the following variables: germination speed (GS), emergence percentage (EMERG), stem and leaf volume (S&LV), root volume (RV), chlorophyll (CHL), secondary roots (SECR), stem diameter (DMT), number of leaves (NL), foliar area (FA), root length (RL), and plant height (PH). Then, we conducted a variance analysis and Tukey’s tests (α£0.05). Results: For each promoter, we observed main effects in EMERG, CHL, and PH for CI; S&LV, NL, FA, and PH for HS; and RL for SA. In genotypes G2 and G3, variables GS, EMERG, NL, and PH were statistically equivalent, DMT varied only in G2, and there were no statistical differences for S&LV, RV, CHL, SECR, FA, and RL. We observed some simple effects in combinations with CI: GS and PH varied in G3, EMERG in G2 and G3, CHL in G1 and G3, DMT in G1 and G2, and S&LV in G2. Study limitations/Implications: Soaking corn for one hour in the solution and weighing the correct amount properly are required, since weighing too much may inhibit germination. Findings/Conclusions: Promoter CI at a dose of 1,000 ppm accelerates the emergence speed of genotypes G2 and G3 in acidic soils.
... Another sustainable production strategy corresponds to biostimulants such as humic substances (HS), which have been studied for their bioactivity in promoting plant growth and development. Within the effects generated by HS in plants, the induction in the proliferation of roots that modify the architecture of the root system is recorded (Chen and Avaid, 1990;Façanha et al., 2002;Zandonadi et al., 2007;Dobbss et al., 2010;Trevisan et al., 2010;Canellas and Olivares, 2014;Canellas et al., 2015) and tolerance to abiotic stress conditions (Guridi-Izquierdo et al., 2017;Veobides-Amador et al., 2018;Kiran et al., 2019). In addition, the H + -ATPase activity that facilitates the absorption of nutrients has been reported, as well as the like auxin effect, which stimulates plant growth (Nardi et al., 2012;Canellas et al., 2015;Nardi et al., 2017). ...
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The common bean crop in dry areas is affected by the climate change and the low availability of nutrients that limits its yield. The objective of this review was to analyze the scope of the scientific literature on the use of inoculants based on Plant growth promoting rhizobacteria (PGPR) and humic substances (HS) in sustainable agronomic management of common bean crop and drought tolerance, for the generation of recommendations applicable to the production cultivation in dry areas from low tropic. An exploratory review on the use of PGPR and SH in common bean was carried out, since the first publications until December 2022 in the databases: Science direct, SciElo, SpringerLink, Scopus, Pubmed and Proquest. The co-inoculation of rhizobia with other PGPR was the most frequent technique in the reviewed articles. However, the combined application with SH allows greater tolerance to the water stress caused by drought. Rhizobia species most reported as efficient were Rhizobium tropici, Rhizobium etli and the strain CIAT 899 (R. tropici). In addition, the strain CIAT 899 was found to be the most useful in inoculant formulations for common beans under drought conditions in Brazil. In Colombia, only one registered product based on Rhizobium phaseoli was found for common bean, although there are no reports of evaluation of this strain under drought stress conditions.
... Another sustainable production strategy corresponds to biostimulants such as humic substances (HS), which have been studied for their bioactivity in promoting plant growth and development. Within the effects generated by HS in plants, the induction in the proliferation of roots that modify the architecture of the root system is recorded (Chen and Avaid, 1990;Façanha et al., 2002;Zandonadi et al., 2007;Dobbss et al., 2010;Trevisan et al., 2010;Canellas and Olivares, 2014;Canellas et al., 2015) and tolerance to abiotic stress conditions (Guridi-Izquierdo et al., 2017;Veobides-Amador et al., 2018;Kiran et al., 2019). In addition, the H + -ATPase activity that facilitates the absorption of nutrients has been reported, as well as the like auxin effect, which stimulates plant growth (Nardi et al., 2012;Canellas et al., 2015;Nardi et al., 2017). ...
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2023. Scopping review: use of biofertilizers and humic substances in Phaseolus vulgaris (Fabaceae) for dry zones. Revista Colombiana de Ciencias Hortícolas 17(2), e16011. Doi: https://doi.
... Another sustainable production strategy corresponds to biostimulants such as humic substances (HS), which have been studied for their bioactivity in promoting plant growth and development. Within the effects generated by HS in plants, the induction in the proliferation of roots that modify the architecture of the root system is recorded (Chen and Avaid, 1990;Façanha et al., 2002;Zandonadi et al., 2007;Dobbss et al., 2010;Trevisan et al., 2010;Canellas and Olivares, 2014;Canellas et al., 2015) and tolerance to abiotic stress conditions (Guridi-Izquierdo et al., 2017;Veobides-Amador et al., 2018;Kiran et al., 2019). In addition, the H + -ATPase activity that facilitates the absorption of nutrients has been reported, as well as the like auxin effect, which stimulates plant growth (Nardi et al., 2012;Canellas et al., 2015;Nardi et al., 2017). ...
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The common bean crop in dry areas is affected by the climate change and the low availability of nutrients that limits its yield. The objective of this review was to analyze the scope of the scientific literature on the use of inoculants based on Plant growth promoting rhizobacteria (PGPR) and humic substances (HS) in sustainable agronomic management of common bean crop and drought tolerance, for the generation of recommendations applicable to the production cultivation in dry areas from low tropic. An exploratory review on the use of PGPR and SH in common bean was carried out, since the first publications until December 2022 in the databases: Science direct, SciElo, SpringerLink, Scopus, Pubmed and Proquest. The co-inoculation of rhizobia with other PGPR was the most frequent technique in the reviewed articles. However, the combined application with SH allows greater tolerance to the water stress caused by drought. Rhizobia species most reported as efficient were Rhizobium tropici, Rhizobium etli and the strain CIAT 899 (R. tropici). In addition, the strain CIAT 899 was found to be the most useful in inoculant formulations for common beans under drought conditions in Brazil. In Colombia, only one registered product based on Rhizobium phaseoli was found for common bean, although there are no reports of evaluation of this strain under drought stress conditions.
... HS, in addition to their roles as regulators of primary and secondary metabolism, have been found to have beneficial effects in attenuating environmental stresses in plants. Studies by Canellas et al. (2015), du Jardin (2015), Van Oosten et al. (2017), andVeobides-Amador et al. (2018) have highlighted the ability of HS to mitigate the negative impacts of soil water deficit, salinization, and exposure to suboptimal temperatures, resulting in improved plant performance and productivity. One example is the foliar application of humic acid (HA) to pepper plants (Capsicum annuum L.) under high salinity conditions (100 mM NaCl). ...
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Because abiotic stresses pose significant challenges to the growth and productivity of crops, the development of plants with greater survival and growth when exposed to unfavorable situations is an objective of several research groups. Biostimulants are substances or microorganisms that, when applied to crops through the foliar or root pathways, serve to enhance various processes related to growth and development. These processes include nutrient absorption, tolerance to environmental stress, and overall harvest quality. Interestingly, biostimulants can achieve these effects even when they possess a low concentration of nutrient elements in their composition. Among the main and most often used biostimulants are plant hormones, algae extract, mycorrhizal fungi, protein hydrolysates, and humic substances (humic and fulvic acids). This review sheds light on the biostimulant effects of applying humic substances to plants experiencing hydric stress conditions and low rainfed cultivation. Additionally, it aims to identify gaps in the current research and highlights areas that require further investigation. Furthermore, the review provides a concise overview of the origin and progression of research on humic substances (HS), including their extraction and obtaining process, as well as their structural characteristics and the relationship between structure, properties, and functions. The review also presents the research findings that support the potential of humic substances influencing crops affected by abiotic stress. These findings highlight the beneficial effects of humic substances in enhancing the resilience and performance of crops facing challenges such as drought, salinity, temperature extremes, and other non-biological stressors. The evidence underscores the significance of humic substances as a valuable tool in mitigating the detrimental impacts of abiotic stress on crop productivity and overall plant health.
... Se ha informado que el vermicompost, a partir de las sustancias húmicas, favorece el desarrollo fenológico de los cultivos al ejercer una acción bioestimuladora sobre el crecimiento de las plantas, mediante la incidencia de las fitohormonas producidas por este compuesto orgánico que estimulan la producción de biomasa (22,23) . ...
Article
La necesidad de buscar alternativas para mejorar la nutrición de los cultivos ante la baja fertilidad de los suelos agrícolas y la escasez de fertilizantes, cobra cada día mayor importancia. Una de estas alternativas es la aplicación de abonos orgánicos y la inoculación con hongos micorrízicos arbusculares (HMA). El objetivo del presente trabajo fue investigar el efecto de las aplicaciones de vermicompost y la inoculación de un biofertilizante micorrízico sobre el suministro de nutrientes de un suelo Gley Nodular Ferruginoso para plantas de millo perla (Panicum italicum L.). Se ejecutaron dos experimentos en condiciones de mesocosmos en el Instituto Nacional de Ciencias Agrícolas (INCA), se estudiaron cuatro proporciones de suelo-vermicompost, con y sin la inoculación micorrízica, en un diseño completamente aleatorizado con estructura factorial y tres repeticiones. Se evaluaron la altura, la masa seca de la biomasa aérea y la concentración y cantidad de nutrientes en las plantas, la frecuencia e intensidad de la colonización y el número de esporas en el suelo. La aplicación de vermicompost incrementó la disponibilidad de nutrientes del suelo y se reflejó en el incremento de la concentración y la cantidad de nutrientes en las plantas, lo que originó mayor crecimiento y desarrollo de estas; en presencia del millo perla la aplicación de vermicompost hizo disminuir la frecuencia e intensidad de la micorrización, lo que inhibió el efecto de la inoculación con hongos micorrízicos arbusculares y no se afectó la producción de esporas en el suelo. Palabras clave: vermicompost, micorrizas arbusculares, Glomus, gleysols
... Se ha informado que el vermicompost, a partir de las sustancias húmicas, favorece el desarrollo fenológico de los cultivos al ejercer una acción bioestimuladora sobre el crecimiento de las plantas, mediante la incidencia de las fitohormonas producidas por este compuesto orgánico que estimulan la producción de biomasa (22,23) . ...
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The need to seek alternatives to improve crop nutrition given the low fertility of agricultural soils and the shortage of fertilizers is becoming increasingly important. One of these alternatives is the application of organic fertilizers and inoculation with arbuscular mycorrhizal fungi (AMF). The objective of the present work was to investigate the effect of vermicompost applications and the inoculation of a mycorrhizal biofertilizer on the nutrient supply of a Gley Nodular Ferruginous soil for pearl millet plants (Panicum italicum L.). Two experiments were carried out under mesocosmic conditions at the National Institute of Agricultural Sciences (INCA), four proportions of soil-vermicompost were studied, with and without mycorrhizal inoculation, in a completely randomized design with factorial structure and three repetitions. The height, the dry mass of the aerial biomass and the concentration and quantity of nutrients in plants, the frequency and intensity of colonization and the number of spores in the soil were evaluated. The application of vermicompost increased the availability of soil nutrients and it was reflected in the increase of the concentration and quantity of nutrients in the plants, which led to greater growth and development of these; in the presence of the pearl millet, the vermicompost application decreased the frequency and intensity of mycorrhization, which inhibited.
... Por otra parte, el uso de los ácidos húmicos en plantas, están relacionados con la pontencialización de la fisiología de las plantas, promover el crecimiento y mejorar la respuesta al estrés (Veobides et al., 2018), formación de raíces adventicias (Baldotto et al., 2012), elongación de la raíz y la formación de pelos de la raíz (Canellas et al. 2015). Todos estos factores incrementan el área de la masa de raíces (volumen de raíces) y la superficie de las raíces, lo que contribuye a una mayor absorción de agua y nutrientes (Eyheraguibel et al., 2008). ...
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El objetivo de la investigación fue evaluar el compor-tamiento de la emergencia y características agronómicas del cultivo de pepino (Cucumis sativus L.) ante la aplicación de quitosano, hongos micorrízicos y ácidos húmicos en condi-ciones protegidas. La investigación se realizó en un invernadero y laboratorio de Biología Molecular y Microbiología de la Universidad Técnica Estatal de Quevedo, Ecuador. El material vegetativo fueron las variedades comerciales de pe-pino (Inivit y Racer), con tratamientos de quitosano (3 g L-1), Glomus cubense (20 esporas/100 g de suelo) y ácidos húmicos (1:30 v/v). Se evaluó emergencia, variables morfométricas, indicadores de crecimiento e indicadores de producción. Los resultados indicaron que la variedad Racer registró el mayor porcentaje de emergencia, el hongo Glomus cubense presen-tó la mayor emergencia (71.7%). Mientras el Glomus cubense en la variedad Inivit mostró la mayor biomasa fresca (22.6 g). En tanto que el quitosano (285.8 g) y el Glomus cubense (277.9 g) influyeron en el peso del fruto. A su vez el quitosano en la variedad Inivit generó el mayor rendimiento (5,703 kg ha-1). En general se comprobó que la aplicación del hongo Glomus cubense induce a incrementos en la emergencia, biomasa fresca, biomasa seca del cultivo de pepino, por su parte la aplicación de quitosano en ambas variedades generó mayor rendimiento.
... Incluso, en la longitud de raíz presentó valores similares al testigo. Veobides et al. (2018) señalan que las sustancias húmicas presentan una estructura compleja con multiplicidad de grupos funcionales lo cual les permite exhibir una gran variedad de efectos beneficiosos entre los que se encuentra su potencial para incrementar los rendimientos y atenuar los efectos de estreses abióticos. Sin embargo, los resultados varían mucho entre especies de plantas en las cuales se apliquen estas sustancias. ...
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RESUMEN El uso de bioestimulantes y biocontroladores en viveros puede ayudar a obtener plántulas de alta calidad. Se evaluó el efecto de la aplicación de bioestimulantes con y sin inoculación de Trichoderma harzianum sobre el crecimiento y desarrollo en plántulas de maracuyá. El ensayo se realizó en una finca ubicada en el municipio Santiago Mariño del estado Aragua, Venezuela, utilizando un diseño de experimento completamente aleatorizado con un arreglo factorial de 5x2 con tres repeticiones, siendo los factores cuatro bioestimulantes comerciales (Terrahumus, Estimulante Plus Manvert, Biorend y Biovida Activador) más un testigo sin aplicación del bioestimulante, y Trichoderma harzianum (presencia o ausencia) para un total de 10 tratamientos. Se evaluaron las siguientes variables: números de hojas (NH), altura de la planta (AP), índice de clorofila (IC), longitud de la raíz (LR), peso seco de la parte aérea (PSPA) y de la parte radical (PSPR). No existió interacción entre los factores evaluados. La aplicación de los bioestimulantes ejerció un efecto positivo en las variables biométricas NH y PSPR con respecto al testigo. Hubo diferencias significativas entre la aplicación de T. harzianum y el testigo, con incrementos de 23,75; 23,84; 12, 27; 88 y 64.3 % para NH, AP, LR, PSPA y PSPR, respectivamente. Se concluye que el uso de sustancias estimulantes y T. harzianum mejora parámetros relacionados con el crecimiento y desarrollo en plántulas de maracuyá. Palabras clave adicionales: Agente biocontrolador, Bacillus, promotor de crecimiento, quitosano ABSTRACT Effect of the application of biostimulants and Trichoderma on growth in maracuyá plants (Passiflora edulis Sims) in nursery The use of biostimulants and biocontrollers in nurseries can favor the obtaining of high quality seedlings. The effect of the application of biostimulants with and without inoculation of Trichoderma harzianum on growth and development of passion fruit seedlings was evaluated. The trial was carried out in a farm located in Santiago Mariño municipality, Aragua State, Venezuela, using a completely randomized design with a 5x2 factorial arrangement and three repetitions. The factors were biostimulants (Terrahumus; Stimulant Plus Manvert; Biorend and Biovida activator, plus a control without product application) and Trichoderma harzianum (presence or absence) for a total of 10 treatments. The evaluated variables were leaf number (LN), plant height (PH), chlorophyll index (CI), root length (RL), shoot dry weight (SDW) and root dry weight (RDW). There was no interaction between the factors. The application of biostimulants exerted a positive effect on the biometric variables such as LN and RDW, with respect to the control. There were significant differences between the application of T. harzianum and the control, with increases of 23.75; 23.84; 12, 27; 88 and 64.3 % for LN, PH, RL, SDW and RDW, respectively. It is concluded that the use of stimulating substances and T. harzianum improves parameters related to growth and development in passion fruit seedlings.
... Los bioestimulantes constituyen sustancias, que por su acción pueden estimular el crecimiento de la planta, mejorar la absorción de nutrientes e incrementar los rendimientos en condiciones de estrés ambiental, independientemente de que contengan elementos nutrientes en su composición (25). ...
... Los investigadores de las SH han dedicado una gran cantidad de esfuerzos, para demostrar el efecto positivo de estas en las plantas y han encontrado que la mezcla de las mencionadas substancias con nutrimentos, provocan efectos positivos en los cultivos desde el punto de vista de la nutrición y la fisiología vegetal ya que tienen un rol relevante en el ciclo de elementos minerales en el suelo (Senesi et al., 1996) y se ha reportado el incremento en longitud de tallo, raíz, hojas, masa fresca y seca y tamaño y calidad de frutos, así como rendimientos en las cosechas (Veobides-Amador et al., 2018). ...
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Los chiles verdes en fresco, en México, son de importancia no solo porque son parte de la dieta alimenticia, sino por la mano de obra que genera su producción; sin embargo, los suelos de los estados productores presentan pH alcalino y esto provoca la fijación del hierro (Fe), el cual es un elemento vital en la calidad de los frutos. Por ello, el objetivo del estudio fue determinar el efecto de un fulvato de fierro (FFe), en la calidad de frutos de chile ‘serrano’ para el cual se utilizaron dosis crecientes de una mezcla de ácidos fúlvicos y sulfato ferroso (FFe) a 200, 400, 600, 800, 1 000 y 1 200 mg kg-1 adicionados en cuatro ocasiones al suelo: al momento del trasplante, a los 15, 45 y 60 ddt. y una solución nutritiva (SN) como control. Las variables de rendimiento y calidad medidas al fruto: peso fresco (PFF), peso seco (PSF), longitud (LF), diámetro (DF), firmeza (FI), sólidos solubles totales (SST) y el fierro (Fe) y el calcio (Ca), al tejido vegetal de follaje. Con la dosis alta de 1 200 mg kg-1 se obtuvo el valor más alto de PFF, LF y DF, mientras que con la dosis de 1 000 mg kg-1 se obtuvo el valor más alto de PSF, FI obtuvo el valor más alto con la dosis de 400 mg kg-1 y con la dosis más baja del complejo orgánico-mineral se obtuvieron los valores más altos de SST y NF. Con respecto a la concentración de nutrientes en tejido foliar la dosis de 1000 mg kg-1 provoco valores óptimos de Fe y cercano al óptimo de Ca, mientras con las dosis más bajas de 200 y 400 mg kg-1 la concentración de ambos minerales se presentó en exceso.
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Esta investigación se desarrolló en la Finca “La Esperanza” perteneciente a la CCS Vega de Pestán, municipio Cauto Cristo, provincia Granma, Cuba. Se ejecutó un experimento en condiciones de campo, entre los meses de diciembre 2022 a abril 2023 en un suelo de tipo Vertisol, el día 10 de noviembre se realizó la siembra en el semillero. El 25 del mismo mes se realizó el trasplante y del 4 de marzo al 25 de abril, la cosecha. Con el objetivo de evaluar el efecto del Quitomax® sobre las principales variables asociadas al rendimiento del pimiento, se utilizó la variedad California Wonder. El diseño empleado fue completamente aleatorizado. Los diferentes tratamientos aplicados de QuitoMax®, se realizaron cuando aparecieron las primeras flores evaluándose dos tratamientos: 1: Aplicación de QuitoMax® con dosis de 300 mg ha-1, y 2: Control, se realizaron mediciones como altura de las plantas, grosor del tallo, número de flores por plantas, número de frutos por plantas, longitud y ancho de los frutos, masa de los frutos y rendimiento. Para el análisis estadístico de los datos obtenidos se empleó un ANOVA de clasificación simple y en todos los casos se aplicó la prueba de Kolmogorov–Smirnov y una prueba de Comparación múltiple de media por T-students para el 5 % de probabilidad del error con el Paquete Estadístico STATISTICA. Los mejores resultados se obtuvieron en el tratamiento donde se aplicó Quitomax® con 8,4 t ha-1 de rendimiento por 2,2 t ha-1 en el tratamiento control.
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El uso de bioestimulantes es una alternativa para mejorar la asimilación de nutrientes por parte de la planta, ya sea aplicados en el agua de riego o vía foliar. El objetivo de esta investigación fue evaluar el efecto de la solución nutritiva Steiner y la aplicación foliar de tres bioestimulantes, sobre parámetros del crecimiento y del rendimiento de dos cultivares de chile jalapeño (Capsicum annuum L.) en condiciones de invernadero. Se establecieron cuatro tratamientos bajo un diseño de bloques completos al azar con cuatro repeticiones, en Juan José Ríos, Ahome, Sinaloa en octubre de 2018. Las variables evaluadas fueron: altura de la planta, diámetro de tallo, peso seco de hoja, peso seco de tallo, longitud de fruto, número de frutos por planta, peso total de fruto, peso de fruto por planta y número de flores. El bioestimulante Giberelin 10 tuvo efecto significativo sobre la altura de la planta. El cultivar Bronco, en promedio de tratamientos, fue sobresaliente por presentar altos valores en los parámetros del crecimiento y del rendimiento evaluados, excepto, en el diámetro de tallo y longitud de fruto, los cuales fueron mayores en el cultivar Forajido. El cultivar Forajido presentó mayor altura de la planta por efecto del tratamiento Giberelin 10, mientras que Bronco exhibió mayor número de frutos por planta con el tratamiento Fiamin-fol y mayor peso de fruto por planta con los tratamientos Maxi-Grow Excel y la solución nutritiva Steiner (testigo).
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Los extractos húmicos de vermicompost constituyen una alternativa para la producción agraria sostenible, que permite disminuir el uso de productos sintéticos, agresivos a la salud humana y animal, y reducir los costos de producción, debido a su fácil acceso para los agricultores. El objetivo de esta investigación fue determinar el efecto que ejerce la aplicación foliar de diferentes diluciones de un extracto líquido, rico en sustancias húmicas, obtenido a partir de un vermicompost de estiércol vacuno, sobre indicadores productivos en plantas de maíz (Zea mays L.). Bajo un diseño completamente aleatorio, con tres repeticiones, se realizaron aplicaciones de tres diluciones del extracto húmico (1:40, 1:60 y 1:80, v:v) en tres momentos (15, 30 y 45 días después de la siembra), y se asumió como control a un grupo de plantas que se mantuvieron sin aplicación. Se analizaron algunas propiedades del extracto obtenido y se evaluó su efecto sobre los indicadores productivos: número de mazorcas por planta, número de granos por hilera, diámetro de la mazorca (con y sin granos), longitud de la mazorca, número de hileras por mazorca, masa de 100 granos, masa de la producción (con y sin paja) y rendimiento. Para la comparación múltiple de medias se utilizó el test de Turkey al 95% de confianza. Ocho variables manifestaron estímulos ante la aplicación de los lixiviados, mostrándose las mejores respuestas en presencia de las diluciones 1:60 y 1:80 (v:v), con rendimientos por encima de las 12,6 t.ha-1 (considerando la masa de la tusa).
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Introducción. Para el establecimiento adecuado de plantaciones de cacao, se deben garantizar tecnologías idóneas para la obtención de posturas (plantas jóvenes sembradas y desarrolladas en bolsas) de calidad en los viveros. Objetivo. Definir indicadores de calidad para posturas de cacao producida vía micro injertos, en función de las fuentes orgánicas y hongos micorrízicos arbusculares en un suelo Cambisol. Materiales y métodos. Entre 2018 y 2019, en el vivero de la Empresa Agroforestal y Coco de Baracoa, se evaluó la inoculación de las cepas Glomus cubense y Rhizoglomus irregulare en sustratos formados por humus de lombriz y cáscara de cacao compostada (3:1,5:1 v/v). Se utilizó un diseño completamente aleatorizado, con cincuenta posturas por tratamiento, de ellas se evaluaron veinticinco. A los cuatro meses se evaluó: altura, diámetro del tallo, masa seca aérea, radical y total, concentración de nutrientes foliares (N, P, K), área foliar, índice de esbeltez, índice de calidad Dickson (ICD) y porcentaje de colonización micorrízica. Se realizó un análisis de varianza de clasificación simple y se aplicó la prueba de comparación de Duncan (95 %). Resultados. La inoculación de G. cubense y R. irregulare, independiente de la fuente de abono orgánico, incrementaron significativamente la masa seca total (39 %), el área foliar (20 %) y el ICD (48 %), respecto los testigos. El ICD se relacionó significativamente (p<0,05) con la masa seca total y el área foliar (R2= 0,97). La inoculación con R. irregulare y G. cubense incrementaron las concentraciones foliares de N, P y K. Conclusiones. Las variables masa seca total, el área foliar, el índice de esbeltez y el ICD, mostraron un carácter integrador del crecimiento de la planta y pueden ser indicadores de calidad para los micro injertos de cacao, a partir de relaciones suelo : abonos orgánicos e inoculación con G. cubense y R. irregulare.
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Stimulatory effects of humic substances (HS) on plant growth have been observed and widely documented. Studies have often shown positive effects on seed germination, root initiation and total plant biomass. The consistency of these observations has been uncertain, predominantly due to the lack of understanding of the plant growth promotion mechanism. Often these effects have been attributed to a direct effect of plant growth hormones; whereas in other instances the term “hormone-like activity” has been used to describe the plant growth stimulation (Chen and Aviad, Humic Substances in Soil and Crop Sciences: Selected Readings, American Society of Agronomy, Soil Science Society of America, 1990; Nardi et al., Humic Substances in Terrestrial Ecosystems, Elsevier Science B.V., 1996). Yet, investigators have been unable to prove that plant growth regulators are present in HS preparations, or the evidence provided remains unconvincing. An alternative hypothesis suggesting that growth enhancement of plants grown in nutrient solution (NS) containing HS is the result of improved micronutrient availability, Fe in particular, has been postulated and tested in the present study. Nutrient solutions containing N, P, K, Ca, Mg, S, B, Mo, Cu, Mn, Zn, and Fe at concentrations considered to be optimal for plant growth were tested for solubility of the Fe, Zn, and Mn, 7 days after preparation. In addition to control solutions at pH values of 5, 6, 7, and 7.5, 0 to 200 mg L of leonardite humic acid (HA) were added to the solutions and they were tested for Fe and Zn solubility. The HA greatly enhanced the maintenance in solution of Fe, in all the tested solutions, and Zn at pH 7.5. Mn mostly remained in solution in its inorganic forms. Plant growth experiments were carried out on both dicotyledonous plants (melons and soybean) and monocotytedonous Poaceae plants (ryegrass), due to the major difference in their Fe uptake mechanism. Plants grown in the absence of Fe exhibited severe Fe deficiency that could only partially be corrected with the addition of mineral Fe salts. The addition of HA or fulvic acid (FA) without addition of Fe, and Zn resulted in partial growth enhancement and correction of Fe deficiency, or none of the two, in the various experiments. This suggests that the growth enhancement effect observed in solutions containing Fe, Zn, and HS was related to the micronutrients rather than to phytohormones. However, the addition of Fe, Zn and either EDTA, HA or FA resulted in healthy, chlorophyll rich plants and enhanced growth, thereby providing evidence that improved Fe, and possibly Zn nutrition is a major mechanism of plant growth stimulation by HS. The use of the term hormone-like activity could be the result of the similarity of the physiological effects obtained in plants enjoying sufficient supply of Fe and Zn.
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Winter rapeseed (Brassica napus) is characterized by a low N recovery in seeds and requires high rates of fertilization to maintain yield. Its nutrient use efficiency could be improved by addition of a biostimulant such as humic acids whose physiological effects have been described previously in some plant species. However, to our knowledge, no study has focused on transcriptomic analyses to determine metabolic targets of this extract. A preliminary screening of ten humic acids revealed a significant effect of one of them (HA7) on rapeseed root growth. Microarray analysis was then used on HA7-treated or non-treated plants to characterize changes in gene expression that were further supported by physiological evidence. Stimulation of nitrogen uptake (+15% in shoots and +108% in roots) and assimilation was found to be increased in a similar manner to growth while sulfate content (+76% in shoots and +137% in roots) was more strongly stimulated leading to higher sulfate accumulation. In parallel, microscopic analysis showed an enhancement of chloroplast number per cell.
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Background Endophytic diazotrophic bacteria colonize several non-leguminous plants and promote plant growth. Different mechanisms are involved in bacteria-induced plant growth promotion, including biological nitrogen fixation (BNF), mineral solubilization, production of phytohormones, and pathogen biocontrol. Herbaspirillum seropedicae is a broad-host-range endophyte that colonizes sugarcane, rice, wheat, sorghum, and maize, and has been used as a biofertilizer. Contrasting results between greenhouse and field experiments have prompted efforts to improve the consistency of the plant response to microbial stimulation. Aims The aim of this study was to evaluate the effect of the presence of humic substances on inoculation of maize (Zea mays L.) with H. seropedicae. Methods Two experiments were conducted: one in the greenhouse using sand and nutrient solution and the other a field trial in soil with low natural fertility and to which was applied N in the form of urea (50 kg ha−1). In the greenhouse, pre-emerging seeds were inoculated with a solution of H. seropedicae (109 cells mL−1) in the presence of humic substances isolated from vermicompost (10, 20, or 30 mg C L−1); in the field trial, bacteria combined with humate were added as a foliar spray (450 L ha−1). Results At early stages (7 and 45 days old) in the greenhouse, the treatment activated plant metabolism including enhancement of plasma membrane H+-ATPase activity, alteration of sugar and N metabolism, and greater net photosynthesis. The number of viable bacterial cells was higher in root tissues when inoculation was in the presence of soluble humic substances. Foliar application of endophytic diazotrophic bacteria and humic substances increased maize grain production 65 % under field conditions. These results show a promising use of humic substances to improve the benefit of endophytic diazotrophic inoculation.
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The application of humic substances (HS) to plants stimulates their biochemical-physiological mechanisms, growth and development. Humified materials exhibit structural characteristics that allow interactions with heavy metal cations dissolved in aqueous environments. Due to their high availability, agriculture-derived vermicomposts (VC) (agro-materials) are excellent raw materials for obtaining HS. Based on these properties, it might be possible to develop biotechnology processes that use agro-materials for environmentally sustainable agriculture. The present article describes the application of a biotechnological working protocol that uses cattle manure vermicompost (CVC) as a raw material for HS. The suggested protocol includes six steps based on the structure-property-biological activity relationships of all the resulting agro-materials. Both the CVC and the resulting agro-materials were characterized using various chemical-physical and spectroscopic techniques. The agro-materials not only increased the agricultural production of different crops at the optimal sowing seasons but also increased production under water and saline stress conditions. The residues arising from the protocol processes were analyzed and found to be useful as decontaminants of heavy metals in aqueous liquid effluents. In addition, the use of such products resulted in increased profits for small- and medium-scale farmers. These studies suggest that agriculture-derived composted organic materials are viable for sustainable agroecological use
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This paper discussed the potential role of humic acids (HA) in preventing oxidative stress in rice plants submitted to water stress. The rice seedlings (Oryza sativa L. cv. IACUB-30) was grown in nutrient solution and HA were extracted from vermicompost and analysed using Fourier-transform infrared (FTIR) spectroscopic and chemical methods. Changes in plant anatomy and morphology before and after stress initiation were employed as biomarkers of plant response. The growth rate over time, water content, dry-mass content, leaf carbohydrates, protein content and amino-acid content were among the parameters evaluated. Peroxidases (POX) activity, proline content, H 2 O 2 content and membrane permeability were also studied. The results show that HA induced POX activity leading to a reduction in H 2 O 2 content and greater conservation of membrane permeability. These results indicate that the HA play an important role as ecological and safety alternative to prevent oxidative stress in plant caused by drought stress. Our findings provide novel evidence for the protective action of HA against oxidative stress caused by water deficits.
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The scientific understanding of the molecular structure of humic substances is critically reviewed here. The traditional view that humic substances are polymers in soil is not substantiated by any direct evidence but only assumed on the basis of laboratory experiments with model molecules and unwarranted results by incorrectly applying either analytical procedures or mathematical treatments developed for purified and undisputed biopolymers. A large body of evidence instead shows an alternative understanding of the conformational nature of humic substances which should be regarded as supramolecular associations of self-assembling heterogeneous and relatively small molecules deriving from the degradation and decomposition of dead biological material. A major aspect of the humic supramolecular structure is that it is predominantly stabilized by weak dispersive forces instead of covalent linkages. Hydrophobic (van der Waals, π-π, CH-π) and hydrogen bonds are responsible for the apparent large molecular size of humic substances, the former becoming more important with the increase of pH. Such novel description of humic substances structure better accounts for their essential role in providing and maintaining soil physical and chemical quality and their reactivity towards pesticides and other environmental soil contaminants. This innovative understanding of the nature of humic substances implies a further development of the science and technology for the control of the chemistry and dynamics of natural organic matter in the soil and the environment.
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Humic acids (HAs) have positive effects on plant physiology, but the molecular mechanisms underlying these events are only partially understood. The induction of root growth and emission of lateral roots (LRs) promoted by exogenous auxin is a natural phenomenon. Exogenous auxins are also associated with HA. Gas nitric oxide (NO) is a secondary messenger produced endogenously in plants. It is associated with metabolic events dependent on auxin. With the application of auxin, NO production is significantly increased, resulting in positive effects on plant physiology. Thus it is possible to evaluate the beneficial effects of the application of HA as an effect of auxin. To investigate the effects of HA the parameters of root growth, Zea mays was studied by evaluating the application of 3 mM C L⁻¹ of HA extracted from Oxisol and 100 µM SNP (sodium nitroprusside) and the NO donor, subject to two N-NO₃⁻, high dose (5.0 mM N-NO₃⁻) and low dose (5.0 mM N-NO₃⁻). Treatments with HA and NO were positively increased, regardless of the N-NO₃⁻ taken, as assessed by fresh weight and dry root, issue of LRs. The effects were more pronounced in the treatment with a lower dose of N-NO₃⁻. Detection of reactive oxygen species (ROS) in vivo and catalase activity were evaluated; these tests were associated with root growth. Under application of the bioactive substances tested, detection of ROS and catalase activity increased, especially in treatments with lower doses of N-NO₃⁻. The results of this experiment indicate that the effects of HA are dependent on ROS generation, which act as a messenger that induces root growth and the emission of LRs.
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Humic substances (HS) represent the organic material mainly widespread in nature. HS have positive effects on plant physiology by improving soil structure and fertility and by influencing nutrient uptake and root architecture. The biochemical and molecular mechanisms underlying these events are only partially known. HS have been shown to contain auxin and an "auxin-like" activity of humic substances has been proposed, but support to this hypothesis is fragmentary. In this review article, we are giving an overview of available data concerning molecular structures and biological activities of humic substances, with special emphasis on their hormone-like activities.
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It is widely reported that some humic substances behave as exogenous auxins influencing root growth by mechanisms that are not yet completely understood. This study explores the hypothesis that the humic acids' effects on root development involve a nitric oxide signaling. Maize seedlings were treated with HA 20 mg C L(-1), IAA 0.1 nM, and NO donors (SNP or GSNO), in combination with either the auxin-signaling inhibitor PCIB, the auxin efflux inhibitor TIBA, or the NO scavenger PTIO. H(+)-transport-competent plasma membrane vesicles were isolated from roots to investigate a possible link between NO-induced H(+)-pump and HA bioactivity. Plants treated with either HA or SNP stimulated similarly the lateral roots emergence even in the presence of the auxin inhibitors, whereas NO scavenger diminished this effect. These treatments induced H(+)-ATPase stimulation by threefold, which was abolished by PTIO and decreased by auxin inhibitors. HA-induced NO synthesis was also detected in the sites of lateral roots emergence. These data depict a new scenario where the root development stimulation and the H(+)-ATPase activation elicited by either HA or exogenous IAA depend essentially on mechanisms that use NO as a messenger induced site-specifically in the early stages of lateral root development.
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A class of organic molecules extracted from atmospheric aerosol particles and isolated from fog and cloud water has been termed humic-like substances (HULIS) due to certain resemblance to terrestrial and aquatic humic and fulvic acids. In light of the interest that this class of atmospheric compounds currently attracts, we comprehensively review HULIS properties, as well as laboratory and field investigations concerning their formation and characterization in atmospheric samples. While sharing some basic features, accumulating evidence suggests that atmospheric HULIS differ substantially from terrestrial and aquatic humic substances. Major differences between HULIS and humic substances, including smaller average molecular weight, lower aromatic moiety content and higher aliphatic moiety and polysaccharide contents, as well as others, are highlighted. Several alternatives are proposed that may explain such differences: (1) the possibility that mono- and di-carboxylic acids and mineral acids abundant in the atmosphere prevent the formation of large humic ''supramolecular associations''; (2) that large humic macromolecules are destroyed in the atmosphere by UV radiation, O3, and OH-radicals; (3) that ''HULIS'' actually consists of a complex, unresolved mixture of relatively small molecules rather than macromolecular entities; and (4) that HULIS formed via abiotic and short-lived oxidative reaction pathways differs substantially from humic substances formed over long time periods via biologically-mediated reactions. It is concluded that a significant effort towards adopting standard extraction and characterization methods is required to develop a better and more meaningful comparison between different HULIS samples. The essential differences as denoted throughout, point to the possibility that HULIS may not be nearly as humic-like as hitherto believed.
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In this study, a detailed characterization of earthworm low molecular size humic substances (LMS) was performed and these substances were used to study their effect on the nitrate influx in roots, tissue nitrate content, and expression of maize genes putatively involved in nitrate uptake in maize (Zea mays L.). The results show that the humic fraction with low molecular size used in this study is endowed with the characteristic structural network described for most humic substances so far isolated and confirm the presence of IAA in this fraction. The results also show that the LMS fraction of humic substances stimulates the uptake of nitrate by roots and the accumulation of the anion at the leaf level. Moreover, the analysis of the expression of genes encoding two putative maize nitrate transporters (ZmNrt2.1 and ZmNrt1.1) and of two maize H+‐ATPase isoforms (Mha1 and Mha2) show that these substances may exert direct effects on gene transcription in roots, as shown for the Mha2 gene, and long‐distance effects in shoots, as observed for the ZmNrt2.1 gene.
Article
Vermicompost (VC) and its extracts (liquid humus) are materials that stimulate the growth and development of the plants, increasing their yield in small and large-scale farming conditions. This paper evaluates the biological effects of a liquid humic extract, previously characterized on the parameters of growth, development and production in the cultivation of maize (Zea mays L.). To the residual solid remaining after the obtaining liquid humus (Liplant®) from VC cattle manure, was applied a new extraction of humic substances (HS) in basic medium. The new liquid extract (ELH) was applied toleaves of corn plants in field conditions at dilutions of 1:10, 1:20 and 1:30 (v:v). To study the effects of ELH it was evaluated growth, development and production parameters. Chemical and physical characteristics of ELH were similar to aqueous humified compounds. The foliar application of ELH to corn plants, exerted positive effects on length and stem diameter, length of cobs without leaves, cobs fresh weight with and without leaves and on the yield of the number of cobs. From these results, it is possible to propose studies to incorporate this new liquid humus in the initial formulation of liquid humus (Liplant® product) or in its technology of application.
Article
The effects of a humic substance (HS) extracted from a volcanic soil on the nitrate assimilation pathway of Zea mays seedlings were thoroughly examined using physiological and molecular approaches. Plant growth, the amount of soluble proteins and amino acids, as well as the activities of the enzymes involved in nitrogen metabolism and Krebs cycle, were evaluated in response to different HS concentrations (0, 1 and 5 mg C L−1) supplied to maize seedlings for 48 h. To better understand the HS action, the transcript accumulation of selected genes encoding enzymes involved in nitrogen assimilation and Krebs cycle was additionally evaluated in seedlings grown for 2 weeks under nitrogen (N) sufficient condition and N deprivation. HS at low concentration (1 mg C L−1) positively influenced nitrate metabolism by increasing the content of soluble protein and amino acids synthesis. Furthermore, the activity and transcription of enzymes functioning in N assimilation and Krebs were significantly stimulated. HS treatment influenced the gene expression of Zea mays plants at transcriptional level and this regulation was closely dependent on the availability of nitrate in the growth medium.
Article
A new era in soil management is emerging on the basis of the novel understanding of soil organic matter (SOM), as a noncovalent supramolecular association of small molecules surviving microbial degradation of plant and animal tissues. The recognition of such molecular nature of humus may have technological implications in agricultural soil management that are yet to be developed. Here we discuss the implications of the supramolecular structure of humus on innovative methods for carbon sequestration in agricultural soil. One method exploits the capacity of humified/hydrophobic matter, such as mature compost amended to soils, to protect from mineralization biolabile hydrophilic molecules rhizodeposited by crops. Another method is the use of biomimetic catalysts to be spread on soils to oxidatively photopolymerize SOM in situ. The formation of intermolecular covalent bonds among soil humic molecules increases the chemical energy required by microbes to mineralize SOM. Both methods were verified in their effectiveness in soil before the scaling up of their use on real field trials under agricultural crops.
Article
Dentro de los intereses de la agricultura de conservación, orgánica y sostenible se ensayan actualmente numerosos productos de origen orgánico, aplicados foliarmente como estimuladores del crecimiento. Con el objetivo de determinar la influencia de la aplicación foliar del extracto líquido de vermicompost, obtenido a partir de estiércol vacuno en índices crecimiento del fríjol (Phaseolus vulgaris L.) cv. CC – 25 - 9, se condujo un experimento en las áreas agrícolas de la Facultad de Agronomía durante los meses de febrero a abril de 2009 en canteros de 3,5 x 0,5 metros sobre un suelo Ferralítico Rojo típico en siembra directa. Las aplicaciones del producto se realizaron cada 7 días a partir de la fase fenológica de primer par de hojas verdaderas a dos concentraciones, 1:60 y 1:70 más un control. Los tratamientos que recibieron los beneficios del producto alcanzaron valores de índices de crecimiento y rendimientos significativamente superiores al control en cada fase fenológica, destacándose la aplicación del extracto líquido de vermicompost de 1:60 como el mejor resultado.
Article
Humic substances (HS), as component of soil organic matter, have been widely studied. Their positive effects on plant physiology have been further demonstrated, but there are no clear evidences about the direct as well as indirect mechanisms regulating these processes.In this paper a transcriptomic approach based on the detection of cDNA-AFLP markers was used to identify candidate genes potentially involved in the regulation of the response to HS in Arabidopsis thaliana.Using 160 primer combinations, the cDNA-AFLP enabled to identify 133 genes putatively involved in plant–HS interaction. Sequence analysis and Gene Ontology classification indicated that a large number of genes involved in developmental and metabolic processes, as well as in transcription regulation or RNA metabolism were identified as HS-regulated. Real-Time PCR analyses confirmed transcription levels of 32 HS-regulated genes.This study demonstrates that HS exert their effects on plant physiology by means of complex transcriptional networks. From the overall transcriptomic results we may hypothesize that HS exert their function through a multifaceted mechanism of action, partially connected to their well demonstrated auxin activity, but involving also IAA-independent signalling pathways.
Article
Animal manure composts contain a substantial amount of organic matter, subse- quently containing a significant amount of humic substances. In this study, we investigated the yields of refuse compost-derived humic substances and their analytical and spectroscopic charac- teristics. The humic acid (HA) and fulvic acids (FAs) of humic substances were extracted from refuse compost and purified. The composition of humic substances were determined by elemen- tal analysis and that of functional groups by Fourier transform infrared spectroscopy (FTIR) and solid-state 13C nuclear magnetic resonance spectroscopy with cross-polarization and magic-angle spinning (CPMAS 13C NMR). Elemental analysis indicates that C and N contents of HA surpass those of FAs. However, total functional group acidities of FAs were much greater than that of HA. Both FTIR and 13C NMR spectra indicate that carboxyl contents of FAs surpass that of HA. The characteristics of compost-derived humic substances affects their reactions with metals es- pecially heavy metals, which in turn affects the mobility and biotoxicities of heavy metals in soil and the associated environments.
Article
Humic substances (HS) contained in the vermicompost, are environmentally friendly materials that restore the chemical and physical properties of soils and improve plant growth. The work described herein was aimed at studying the HA–root interactions and their relationship with some components of antioxidative metabolism in rice (Oryza sativa L.). These studies encompassed aspects ranging from the activity of enzymes in antioxidative metabolism and the relationship between these enzymes and the reactive oxygen species (ROS) content in rice to the expression of genes encoding rice tonoplast intrinsic proteins (OsTIP), a sub-family of aquaporins. The HA–root interactions were also characterized. The results from these studies demonstrate that the interaction of HA with the radicular system in plants activates antioxidative enzymatic function, thus controlling the ROS content and modifying OsTIP expression. Microscopic and spectroscopic techniques confirmed the interactions between HA fragments of lower structural complexity and the radicular system. It appears that HA act in plants via a specific form of stress that is detected by anti-stress defense systems in plants. These HA applied to plants can protect against water stress in degraded soils.
Article
The scientific understanding of the molecular size and shape of humic substances (HS) is critically reviewed. The traditional view that HS are polymers in soil is not substantiated by any direct evidence but is assumed only on the basis of laboratory experiments with model molecules and unwarranted results produced by incorrectly applying either analytical procedures or mathematical treatments developed for purified and undisputed biopolymers. A large body of evidence shows an alternative understanding of the conformational nature of HS, which should be regarded as supramolecular associations of self-assembling heterogeneous and relatively small molecules deriving from the degradation and decomposition of dead biological material. A major aspect of the humic supramolecular conformation is that it is stabilized predominantly by weak dispersive forces instead of covalent linkages. Hydrophobic (van der Waals, π-π, CH-π) and hydrogen bonds are responsible for the apparent large molecular size of HS, the former becoming more important with the increase of pH. This innovative understanding of the nature of HS implies a further development of the science and technology for the control of the chemistry and reactivity of natural organic matter in the soil and the environment.
Article
The physiological effects of humic substances (HS) on some aspects of plant growth and metabolism are examined. Evidence has been presented on that the effect of HS on plant growth depends on the source, concentration and molecular weight humic fraction. While a low molecular size (LMS<3500 Da) fraction easily reaches the plasmalemma of higher plant cells and, in part, is taken up into them, a high molecular size fraction (HMS>3500 Da) is not absorbed and can interact only with the cell wall. Therefore, a LMS fraction is the major candidate for determining the positive effects of HS on plant growth. The latter effects are in part exerted at the level of the plasma membrane by positively influencing the uptake of some nutrients, and in particular that of nitrate. The effects on the intermediary metabolism are less understood, albeit it seems that HS may influence both respiration and photosynthesis. Humic matter appears also to display an hormone-like activity. It is not clear if this activity is strictly linked to the chemical structure of HS or whether it depends on hormones of microbial origin entrapped into them. In any case, HS exhibit stimulatory effects on plant cell growth and development.
Article
The aim of the present work is the study of the complex organic matter present in sediments from two retention ponds, Wissous located in an urban area and Cheviré receiving road runoff. The main questions are relative to the origins, the transformation processes and the final structure of organic matter. The sediment from Wissous contained 22.3 wt.% of organic matter, compared to 14.7 wt.% for the Cheviré sediment. FT-IR spectra did not reveal significant differences. Total organic matter (TOM) was fractionated into lipids and humic-like substances. “Humic acid” and “humin” fractions from the two samples were studied using pyrolysis techniques in presence of alkylating agents. The nature of TMAH pyrolysis products from Wissous and Cheviré “humic acids” did not differ. The presence of C7–C28 aliphatic monocarboxylic acid methyl esters with a dominant short <C20 mode (C16 major) containing iso and anteiso C15, C17 acids, and a minor C20–C28 mode indicates a mixed bacterial and vegetal contribution. Pyrolysis of “humin” afforded the same kinds of products. The bacterial contribution with short acids and typical branched iso and anteiso C15 and C17 acids was dominant for all the samples. Nevertheless the plant contribution appeared to be somewhat more pronounced in “humic acids” than in “humin” for Cheviré, and in humin for Wissous. Pyrolysis in presence of TEAAc allowed to distinguish three origins for the fatty acid methyl esters produced after TMAH pyrolysis of “humic acids” and “humins”. The presence in the TEAAc products of fatty acid methyl esters (identified as methyl esters) showed that plant fatty acid methyl esters were trapped in the matrix, particularly for Wissous. Short acids including bacterial iso and anteiso C15, C17 acids and identified as ethyl esters were present as trapped acids R-COOH. The last part which cannot react with TEAAc corresponds to acids which are bound to the matrix by ester groups and thus incorporated to the macromolecular structure.
Article
We size fractionated a soil humic acid (HA) by preparative high performance size exclusion chromatography (HPSEC) and evaluated the analytical capacity of humeomics to isolate and identify humic molecular components in the separated size-fractions. HA and its three size-fractions were chemically fractionated to extract non-covalently bound organosoluble compounds (ORG1), weakly ester-bound organosoluble (ORG2) and hydrosoluble constituents (AQU2), strongly ester-bound organosoluble components (ORG3), and final unextractable residues (RES4). According to their solubility, the extracts were characterized by either GC-MS or on-line thermochemolysis/GC-MS techniques. The humeomic sequence showed that the analytical yields of identified compounds in either ORG or AQU extracts of size-fractions were invariably larger than for the unfractionated HA. This was attributed to a weaker conformational stability of humic suprastructures obtained by HPSEC fractionation, thereby enabling an improved separation and identification of single humic molecules. In line with the supramolecular understanding of humic substances, we found that hydrophobic compounds were mainly distributed in the largest size-fraction, while hydrophilic components were eluted in the smallest size-fraction. Furthermore, compounds with linear chains or stackable aromatic rings associated in regular structures were more abundant in the former fraction, whereas irregularly shaped compounds, that hindered association in larger size, were mostly found in the latter fraction. Thus the structural characteristics of single humic molecules determined their mutual association in humic suprastructures, as well as their conformational strength and shape. The lack of de novo synthesized macropolymers in the unfractionated soil humic matter was confirmed by the absence of RES4 fractions in the separated size-fractions. Our results indicate that humeomics capacity to reveal the complex molecular composition of humic suprastructures was significantly improved by subjecting humic matter to a preliminary HPSEC fractionation.
Article
Under environmental stresses, plant development is adaptively modulated. This modulation is influenced by the steady-state balance (homeostasis) between reactive oxygen species (ROS) and phytohormones. Frequently observed symptoms in plant stress adaptation responses include growth retardation, reduced metabolism and photosynthesis, reallocation of metabolic resources and increased antioxidant activities to maximize plant survival under adverse environmental conditions. In view of stress-induced morphogenetic changes during adaptation, ROS and auxin are the main players in the regulatory networks because both are strongly affected by exposure to environmental cues. However, the mechanisms underlying the crosstalk between ROS and auxin are poorly understood. In this review, we aim at surveying how the integration of environmental stress-related signals is modulated by crosstalk between ROS and auxin regulatory networks.
Article
A high molecular weight humic fraction (>3,500 Da) was characterized chemically by DRIFT and 1H NMR spectroscopy, and was applied to Zea mays L. plants to evaluate its effect on phenylpropanoid metabolism. The activity and gene expression of phenylalanine (tyrosine) ammonia-lyase (PAL/TAL), and the concentrations of phenolics and their amino acid precursors phenylalanine and tyrosine were assayed. Maximum induction of PAL/TAL activity and expression was obtained when the concentration of added humic substance was 1 mg C/l hydroponic solution. Phenylalanine and tyrosine significantly decreased (-16% and -22%, respectively), and phenolic compounds increased in treated plants. The effects of the humic substance could be ascribed partly to indoleacetic acid (27 nmol/mg C) in the humic fraction. Our results suggest that this humic fraction induces changes in phenylpropanoid metabolism. This is the first study that shows a relationship between humic substances and the phenylpropanoid pathway.
Article
Preparative high performance size-exclusion chromatography (HPSEC) was applied to humic acids (HA) extracted from vermicompost in order to separate humic matter of different molecular dimension and evaluate the relationship between chemical properties of size-fractions (SF) and their effects on plant root growth. Molecular dimensions of components in humic SF was further achieved by diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY-NMR) based on diffusion coefficients (D), while carbon distribution was evaluated by solid state (CP/MAS) (13)C NMR. Seedlings of maize and Arabidopsis were treated with different concentrations of SF to evaluate root growth. Six different SF were obtained and their carbohydrate-like content and alkyl chain length decreased with decreasing molecular size. Progressive reduction of aromatic carbon was also observed with decreasing molecular size of separated fractions. Diffusion-ordered spectroscopy (DOSY) spectra showed that SF were composed of complex mixtures of aliphatic, aromatic and carbohydrates constituents that could be separated on the basis of their diffusion. All SF promoted root growth in Arabidopsis and maize seedlings but the effects differed according to molecular size and plant species. In Arabidopsis seedlings, the bulk HA and its SF revealed a classical large auxin-like exogenous response, i.e.: shortened the principal root axis and induced lateral roots, while the effects in maize corresponded to low auxin-like levels, as suggested by enhanced principal axis length and induction of lateral roots. The reduction of humic heterogeneity obtained in HPSEC separated size-fractions suggested that their physiological influence on root growth and architecture was less an effect of their size than their content of specific bioactive molecules. However, these molecules may be dynamically released from humic superstructures and exert their bioactivity when weaker is the humic conformational stability as that obtained in the separated size-fractions.
Grande naine'(Musa AAA) transformadas con el gen de osmotina ap24 al estrés hídrico
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A relação da planta com a água. Brasil: Universidade Federal Rural do Rio de Janeiro
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Humosfera : tratado preliminar sobre a química das substâncias húmicas