ABSTRACT In semi-arid regions, where seasonal drought or irregular rainfall distribution are common occurrences, agricultural management techniques or strategies, such as the use of bone meal and/or hydrogel, can mitigate adverse conditions and ensure crop production. This study aimed to evaluate the efects of bone meal doses (0, 250, 500, 750 and 1,000 g pit−1), in association or not with hydrogel (0 and 5 g pit−1, respectively), on the leaf nutrient content of the dwarf cashew cultivar BRS 226. The leaf nutrient contents were evaluated during two growing seasons. For being a good source of macronutrients, the bone meal increased the levels of N, P, Ca, K and Mg in the dwarf cashew leaves. The leaf contents of the micronutrients Zn, Fe and Mn decreased with increasing bone meal doses. The nutrient accumulation in the leaves of the dwarf cashew planted in pits with bone meal and hydrogel has the following order: N > K > Ca > Mg > P > Mn > Fe > Zn > Cu. The application of bone meal at levels close to 600 g pit−1, mainly with the use of hydrogel, is a viable fertilizer alternative for dwarf cashew.

RESUMO Em regiões semiáridas, onde a seca sazonal ou a distribuição irregular de chuvas são ocorrências comuns, técnicas ou estratégias de manejo agrícola, como o uso de farinha de osso e/ou hidrogel, podem mitigar condições adversas e garantir a produção agrícola. Objetivou- se avaliar os efeitos de doses de farinha de osso (0, 250, 500, 750 e 1,000 g cova−1), em associação ou não com hidrogel (0 e 5 g cova−1, respectivamente), sobre o teor de nutrientes foliares da cultivar de cajueiro-anão BRS 226. Os teores de nutrientes nas folhas foram avaliados durante duas safras. Por ser boa fonte de macronutrientes, a farinha de osso aumentou os níveis de N, P, Ca, K e Mg nas folhas do cajueiro anão. Os teores foliares dos micronutrientes Zn, Fe e Mn diminuíram com o aumento das doses de farinha de osso. O acúmulo de nutrientes nas folhas do cajueiro anão plantado em covas com farinha de osso e hidrogel tem a seguinte ordem: N > K > Ca > Mg > P > Mn > Fe > Zn > Cu. A aplicação de farinha de osso em níveis próximos a 600 g cova−1, principalmente com o uso de hidrogel, é uma alternativa viável de fertilizante para cajueiro-anão.

Resumen. Los hidrogeles biodegradables obtenidos de fuentes naturales son materiales no tóxicos y con una gran capacidad de retención de agua, por lo que constituyen una valiosa alternativa para el uso racional del agua en aplicaciones agrícolas. El objetivo del presente trabajo fue evaluar el efecto de hidrogeles formulados a partir de polímeros naturales (alginato, polisacáridos de nopal, polisacáridos de aloe y quitosano) sobre la capacidad de retención de agua, el potencial biodegradable, así como la morfometría y germinación de plántulas de alfalfa en comparación con el hidrogel de poliacrilato de potasio (control comercial). Se caracterizaron un total de 36 tratamientos bajo condiciones controladas a nivel laboratorio, obteniendo que, en comparación con el control comercial, el hidrogel de PSGCL presentó el mayor valor de retención de agua y todos los demás tratamientos obtenidos a partir de polímeros naturales presentaron mayor potencial biodegradable. En cuanto a la germinación de plántulas de alfalfa respecto al testigo absoluto y al resto de los tratamientos.

Abstract. Biodegradable hydrogels obtained from natural sources are non-toxic materials with a large water retention capacity, hence a valuable alternative for the rational use of water in agriculture applications. The aim of the present work was to evaluate the effect of hydrogels formulated from natural polymers (alginate, nopal polysaccharides, aloe polysaccharides, and chitosan) on water retention capacity, biodegradable potential as well as the morphometry and germination of alfalfa seedlings compared with potassium polyacrylate hydrogel (commercial control). A total of 36 treatments were characterized under controlled conditions at the laboratory level obtaining that in comparison with the commercial control, PSGCL hydrogel presented the highest water retention value, whereas all the hydrogels obtained from natural polymers had greater biodegradable potential. Regarding to germination of alfalfa seedlings, PSGP hidrogel presented the most outstanding performance in term of percentage of germination, plant height and foliage development with respect to absolute control and the rest of the treatments.

ABSTRACT The productivity of the Adultrap® trap was compared to that of modified adultrap traps. Two structural changes were tested, a cover was placed at the entrance of the trap at two different heights. A comparison was also made with traps containing hydrogel to replace the water in the reservoir. The positivity rates of all the trap types were calculated and compared. The hydrogel models were more productive because they collected eggs, larvae, and adults. The trap that removed the protective screen and replaced the water with the hydrogel was 18.5 times larger than the original trap (p = 0.001). There was an increase in the productivity for the total collection of mosquitoes. The collection of eggs, larvae, and adults can contribute to the construction of more robust infestation indices. In addition, it allows for the collection of live specimens and the development of studies.

RESUMO Comparou-se a produtividade da armadilha Adultrap® com armadilhas Adultrap modificadas. Foram testadas duas mudanças estruturais e foi colocada uma tampa na entrada da armadilha em duas alturas diferentes. Também foi feita uma comparação entre armadilhas contendo água no reservatório e armadilhas contendo hidrogel em substituição à água do reservatório. As taxas de positividade de todos os tipos de armadilha foram calculadas e comparadas. Os modelos com hidrogel foram mais produtivos porque coletaram ovos, larvas e adultos. A armadilha que retirou a tela de proteção e substituiu a água pelo hidrogel, foi 18,5 vezes maior que a armadilha original (P=0,001). Houve aumento na produtividade para a coleta total de mosquitos. A coleta de ovos, larvas e adultos pode contribuir para a construção de índices de infestação mais robustos, além de permitir a coleta de espécimes vivos e o desenvolvimento de estudos.

ABSTRACT Purpose: To evaluate the efficacy of soft HydroCone silicone hydrogel contact lenses in patients with posterior microphthalmos. Methods: The charts of 13 patients with posterior microphthalmos (26 eyes) who were fitted with soft HydroCone silicone hydrogel contact lenses were reviewed retrospectively. All the patients underwent assessments of uncorrected and best spectacle-corrected visual acuity and cycloplegic refraction. They were fitted with contact lenses according to the parameter values obtained from the topographical analysis and best contact lens-corrected visual acuity measurement. Results: The spherical equivalents of the right and left eyes ranged from 10.00 to 19.25 diopters and from 11.00 to 21.5 diopters, respectively. The mean axial and posterior chamber lengths were shorter than those of the age-matched population. However, the mean values of the anterior segment parameters such as horizontal visible iris diameter, central anterior chamber depth, lens thickness, and central corneal thickness were in the normal range. The mean keratometric measurements revealed increased corneal curvature compared with that in the normal population. The mean best contact lens-corrected visual acuity was significantly higher than the mean best spectacle-corrected visual acuity for both eyes (p=0.045). Conclusion: HydroCone silicon soft contact lenses provided better visual acuity than spectacles in the patients with posterior microphthalmos in this study.

RESUMO Objetivo: Avaliar a eficácia das lentes de contato gelatinosas HydroCone, de hidrogel com silicone, em pacientes com microftalmia posterior. Métodos: Foram revisados retrospectivamente 26 olhos com microftalmia posterior, a partir dos prontuários de 13 pacientes que receberam lentes de contato gelatinosas HydroCone, de hidrogel com silicone. Todos os pacientes foram submetidos ao exame de acuidade visual não corrigida e com melhor correção por óculos e com refração cicloplégica. Todos os pacientes receberam lentes de contato de acordo com os parâmetros obtidos na análise topográfica e foi obtida a melhor acuidade visual corrigida com lentes de contato. Resultados: O equivalente esférico do olho direito variou de 10,00 a 19,25 dioptrias, e o do olho esquerdo de 11,00 a 21,5 dioptrias. Os comprimentos médios axiais e das câmaras posteriores foram menores do que para a população de mesma idade. No entanto, os valores médios dos parâmetros do segmento anterior, como o diâmetro horizontal visível da íris, a profundidade da câmara anterior central, a espessura da lente e a espessura central da córnea estavam dentro da faixa normal. Os valores médios da ceratometria revelaram curvatura corneana aumentada em relação à população normal. A média da melhor acuidade visual corrigida com lentes de contato foi significativamente maior que a média da melhor acuidade visual corrigida com óculos em ambos os olhos (p=0,045). Conclusão: As lentes de contato gelatinosas de silicone HydroCone proporcionam melhor acuidade visual que óculos em pacientes com microftalmia posterior.

Resumen Introducción: La obstrucción intestinal por ingesta accidental de cuerpos extraños se presenta muy rara vez en la edad pediátrica debido a que del 80 al 90% de los objetos pueden pasar libremente por el tracto gastrointestinal. Caso clínico: Se aborda el caso de una paciente de sexo femenino de 1 año 2 meses quien presentó obstrucción intestinal debido a la ingesta de esferas de hidrogel (poliacrilato de sodio). Dichas esferas, que son utilizadas como juguetes didácticos o sensoriales, aumentan de 200 a 400 veces su tamaño inicial mediante la absorción de agua. Se realizó radiografía abdominal en proyección decúbito supino, donde llamó la atención el hallazgo de defecto de llenado redondeado en asa de flanco derecho, ya que las esferas de hidrogel son radiolúcidas. El diagnóstico se estableció mediante ultrasonido abdominal, donde se reportó líquido libre peritoneal con datos de suboclusión por cuerpos extraños a nivel intestinal. Se indicó tratamiento conservador, encontrando persistencia de aumento de perímetro abdominal. Se realizó enterotomía y se encontraron las esferas impactadas a 30 centímetros de la válvula ileocecal. Conclusiones: Las esferas de hidrogel son peligrosas para la población pediátrica. La evolución de la paciente fue favorable debido al conocimiento del objeto extraño ingerido. Sobresale la conducta expectante que se tuvo que desempeñar debido a que se desconocía el crecimiento de las esferas y en qué momento no podrían continuar su paso por el tracto gastrointestinal.

Abstract Background: Bowel obstruction due to accidental ingestion of foreign objects occurs rarely in children because 80 to 90% of the objects can pass freely through the gastrointestinal tract. Case report: We report a case of a 14-month-old infant who presented bowel obstruction caused by the ingestion of hydrogel beads (sodium polyacrylate). Hydrogel beads are used as sensory and didactic toys that can increase their initial size 200 to 400 times by liquid absorption. An abdominal X-ray was perfomed in anteroposterior supine projection, where a round filling defect at the loop of the right flank was detected; this came to our attention because hydrogel beads are usually radiolucent. The diagnosis was established by abdominal ultrasound where free intraperitoneal fluid was reported with data of small bowel pseudo-obstruction by foreign objects. Conservative treatment was prescribed, finding persistence of increased abdominal perimeter, so an enterotomy was performed for their removal; finding impacted hydrogel beads 30 centimeters from the ileocecal valve. Conclusions: Hydrogel beads are dangerous for the pediatric population. The evolution of the patient was favorable thanks to the knowledge of the foreign objects ingested. The expectant behavior that had to be executed, stands out because we had no knowledge as to the maximum size of the hydrogel in the gastrointestinal tract.

ABSTRACT In this study, we found that a copolymer of acrylamide and potassium acrylate (Hydrogel 3005K4®) in two particle sizes (1-2 mm and 2-4 mm) could absorb conditioned Galhaup media recovered from Trametes versicolor growth containing ligninolytic enzymes. It was found that the most efficient absorption capacity of the copolymer in the presence of the conditioned medium was using a 0.2:10 weight/volume (w/v) copolymer-conditioned medium ratio for both particle sizes. This ratio is a quarter of its absorption capacity in distilled water. A different desorption behavior of the medium was also observed, depending on whether the copolymer was exposed to the soil, water, or air. The ligninolytic enzyme media absorbed by the Hydrogel 3005K4® showed slower desorption of conditioned medium in soil for 10 days and faster desorption in air and water between 24 and 72 h. The enzymes were capable to preserve the activity after absorption. The versatility of this vector holding the enzymes may be attractive for reduce the presence of organic compounds (pesticides, polycyclic aromatic hydrocarbons, synthetic and natural dyes) on soil as part of a bioremediation technique, with a possibility of being reused.

RESUMEN En este estudio se encontró que un copolímero de acrilato de acrilamida y potasio (Hidrogel 3005K4®) en dos tamaños de partícula (1-2 mm y 2-4 mm), puede absorber medio condicionado de Galhaup recuperado del crecimiento de Trametes versicolor que contiene enzimas ligninolíticas. Se encontró que la capacidad de absorción más eficiente del copolímero en presencia del medio condicionado fue empleando una proporción de 0.2:10 peso/volumen (p/v) de copolímero-medio condicionado para ambos tamaños de partícula. Esta proporción es un cuarto de su capacidad de absorción en agua destilada. Se encontró un comportamiento diferente de desadsorción del medio enzimático contenido en el hidrogel, dependiendo de si el copolímero estaba o no expuesto al suelo, agua o aire. El medio con las enzimas ligninolíticas absorbido por el Hidrogel 3005K4® mostró una desadsorción lenta del medio condicionado en el suelo a los 10 días y una rápida desadsorción en aire y agua entre las 24 y 72 h. Las enzimas fueron capaces de continuar con su actividad después de la absorción. La versatilidad de este vector que contiene las enzimas puede ser atractiva para reducir la presencia de compuestos orgánicos (plaguicidas, hidrocarburos aromáticos policíclicos, colorantes sintéticos y naturales) en el suelo como parte de las técnicas de biorremediación.

Abstract Enterolobium cyclocarpum is a multipurpose tree species whose growth and survival in plantations are unknown. The objective was to evaluate the effect of different nursery growing media and auxiliary treatments to mitigate water stress on the performance of E. cyclocarpum plants established in the field. The seeds were sown in three different types of substrates: 1) base mixture (peat, vermiculite and agrolite), 2) aerobic compost and 3) native soil. Each group of plants by type of substrate was divided into four subgroups that were assigned different auxiliary treatment to mitigate water stress: 1) irrigation, 2) hydrogel (2 g plant-1), 3) hydrogel (4 g plant-1) and 4) natural conditions (control). The results indicate that the type of substrate influences the survival and growth of the plants, being native soil the one that promotes higher values. It was found that there is a positive relationship between the diameter of the plants and the probability of survival, this variable being a basic quality indicator of the plants grown in the nursery. The auxiliary treatment of hydric stress significantly affected the growth in diameter and height, being irrigation the one that increased the values, with the exception of the diameter in the base mixture.

Resumen Enterolobium cyclocarpum es una especie arbórea multipropósito cuyo crecimiento y supervivencia en plantaciones se desconoce. El objetivo fue evaluar el efecto de tres medios de crecimiento en vivero y tratamientos auxiliares para mitigar el estrés hídrico en el desempeño de plantas de E. cyclocarpum establecidas en campo. Las semillas se sembraron en tres diferentes tipos de sustrato: 1) mezcla base (turba, vermiculita y agrolita), 2) composta aeróbica, y 3) tierra de monte. Cada grupo de plantas por tipo de sustrato se dividió en cuatro subgrupos a los que se les asignó diferente tratamiento auxiliar para mitigar el estrés hídrico: 1) riego, 2) hidrogel (2 g planta-1), 3) hidrogel (4 g planta-1), y 4) condiciones naturales (testigo). Los resultados indican que el tipo de sustrato influye en la supervivencia y crecimiento de las plantas, siendo la tierra de monte la que promueve mayores valores. La relación entre el diámetro de plantas con la probabilidad de supervivencia fue positiva; esta variable es un indicador de la supervivencia en campo durante los primeros años de la plantación. El tratamiento auxiliar para mitigar el estrés hídrico afectó significativamente el crecimiento en diámetro y altura; el riego aumentó los valores, con excepción del diámetro en mezcla base.

RESUMO Os hidrogéis favorecem a retenção de umidade no substrato e podem atenuar os efeitos do estresse salino na produção de plantas em vaso. Nesse contexto, buscou-se avaliar o uso do hidrogel para mitigar os danos causados pela salinidade da água de irrigação na emergência, crescimento e índice térmico de mudas de Tagetes patula L. A pesquisa foi realizada em casa-de-vegetação, em setembro de 2020, no município de Fortaleza, estado do Ceará, Brasil. O delineamento utilizado foi em blocos casualizados em parcelas subdivididas. As parcelas corresponderam a sete níveis de condutividades elétricas da água de irrigação - CEa (0,5, 1,0, 2,0, 3,0, 4,0, 5,0 e 6,0 dS m-1) e as subparcelas corresponderam a quatro concentrações de hidrogel (0, 1,0, 2,0 e 3,0 g L-1), com cinco repetições e cada subparcela foi composta por 27 sementes. A aplicação de 3,0 g de hidrogel L-1 de substrato favoreceu a produção de folhas e reduziu o estresse térmico nas plantas associado ao aumento da salinidade do substrato até 6,0 dS m-1. A utilização de 3,0 g L-1 de hidrogel incrementou a altura das plântulas, massa seca da folha e massa seca total em comparação aos tratamentos sem o polímero retentor de água, mesmo em níveis moderados (2,0 a 3,0 dS m-1) e altos de salinidade (4,0 a 6,0 dS m-1), indicando assim possível efeito mitigador dos danos causados pela salinidade da água de irrigação. Entretanto, a intensidade desse efeito mitigador deminui nos maiores níveis de estresse salino.

ABSTRACT Hydrogels favor moisture retention in the substrate and can attenuate the effects of salt stress on the production of potted plants. In this context, this research sought to evaluate the use of hydrogel to mitigate the damage caused by the salinity of irrigation water on the emergence, growth, and thermal index of Tagetes patula L. seedlings. The research was carried out in a greenhouse, in September 2020, in the municipality of Fortaleza, Ceará State, Brazil. The design used was randomized blocks in a split plot. The plots corresponded to seven levels of electrical conductivity of the irrigation water - ECw (0.5, 1.0, 2.0, 3.0, 4.0, 5.0, and 6.0 dS m-1) and the subplots corresponded to four hydrogel concentrations (0, 1.0, 2.0, and 3.0 g L-1), with five replicates and each subplot consisted of 27 seeds. The application of 3.0 g hydrogel L-1 of substrate favored the production of leaves and reduced the thermal index in plants associated with the increase in the salinity of the substrate up to 6.0 dS m-1. The use of 3.0 g L-1 hydrogel increases seedling height, leaf dry mass, and total dry mass compared to treatments without water-retaining polymer, even at moderate (2.0 to 3.0 dS m-1) and high (4.0 to 6.0 dS m-1) salinity levels, thus indicating a possible effect of mitigation of damage caused by the salinity of the irrigation water. However, the intensity of this mitigating effect decreases at higher levels of salt stress.

RESUMO O objetivo deste estudo foi desenvolver um novo sistema subgengival de liberação sustentada para administração local de cloridrato bioativo de minociclina para tratamento da doença periodontal em cães. O sistema incorporou o cloridrato de minociclina-cálcio-dextrano sulfato de sódio em um hidrogel Pluronic F127 termorresponsivo. O cloridrato de minociclina foi liberado do sistema por até 10 dias e a cinética de liberação se ajustou ao modelo da lei de potência. O meio de liberação apresentou uma diferença estatística significativa na atividade antimicrobiana para Aggregatibacter actinomycetemcomitans. Os resultados mostraram que o sistema foi um promissor sistema subgengival de liberação sustentada de cloridrato de minociclina para o tratamento da doença periodontal em cães.

ABSTRACT The objective of this study was to develop a novel subgingival sustained-release system for local delivery of bioactive minocycline hydrochloride for periodontal disease treatment in dogs. The system incorporated the Minocycline hydrochloride-Calcium-Dextran sulfate sodium into a thermoresponsive Pluronic F127 hydrogel. Minocycline hydrochloride was sustained release from the system for up to 10 days and the release kinetics fit the power law model. The release medium had a significant statistical difference in antimicrobial activity to Aggregatibacter actinomycetemcomitans. The results showed the system was a promising subgingival sustained-release minocycline hydrochloride delivery system for periodontal disease treatment in dogs.

Resumen Introducción y objetivos : La práctica de la restauración es una fuente de valiosa experiencia que, analizada y difundida, contribuye a la mejora de las intervenciones de recuperación de espacios degradados. Desde esta concepción, en este trabajo evaluamos una plantación de Prosopis denudans var. denudans en una zona árida ubicada en el Área Protegida Auca Mahuida (Neuquén, Argentina). Los objetivos fueron: analizar el efecto de las aplicaciones de hidrogel a los 11 meses de la siembra y determinar la incidencia de depredación de vertebrados herbívoros en el mismo período. M&M : Se plantaron un total de 651 plantines de vivero distribuidos en dos canteras abandonadas. Aplicamos los tratamientos % l de hidrogel; 1 l de hidrogel y control (sin hidrogel) y protección vs no protección de malla metálica para evaluar supervivencia y predación. Los resultados fueron analizados con modelos lineales generalizados. Resultados : La sobrevivencia fue significativamente mayor y estadísticamente diferente para plántulas con % l de hidrogel y malla metálica de protección. Las plantas protegidas no fueron predadas, y la supervivencia en plantas no protegidas se redujo en un 50% aproximadamente. Conclusiones : Los resultados muestran que las probabilidades de supervivencia pueden ser mayores con protectores frente a mamíferos herbívoros e hidrogel, en plantaciones de restauración. Sin embargo, es necesario incrementar los estudios sobre las relaciones entre el crecimiento radicular y dosis de hidrogeles en diferentes condiciones edáficas, particularmente en especies que pueden ser marco o fundantes para la recuperación de áreas degradadas.

Summary Background and aims : The practice of restoration is a source of valuable experience that, analyzed and disseminated, contributes to the improvement of interventions for the recovery of degraded areas. From this conception, in this work we evaluate an outplanting of Prosopis denudans var. denudans in an arid zone located at Auca Mahuida Protected Area (Neuquén, Argentina). The objectives were: to analyze the effect of hydrogel applications after 11 months after planting; and determine the incidence of predation of herbivorous vertebrates in the same period. M&M : A total of 651 nursery seedlings were planted distributed in two abandoned quarries. We apply the treatments % l of hydrogel; 1 l of hydrogel and control (without hydrogel), and protection vs. no protection of metal mesh to evaluate survival and predation. The results were analyzed with generalized linear models. Results : The survival was significantly higher and statistically different for seedlings with % l of hydrogel and metal mesh protection. The protected plants were no predated, and survival in no protected plants was reduced 50% approximately. Conclusions : The results show that the chances of survival may be greater with protectors against herbivorous mammals and hydrogel in restoration plantations. However, it is necessary to increase studies on the relationships between root growth and hydrogel doses in different edaphic conditions, particularly in species that can be the framework for the recovery of degraded areas.

RESUMO No semiárido brasileiro o déficit hídrico é um dos principais fatores que compromete o crescimento e o rendimento produtivo das culturas, inclusive do maracujazeiro- amarelo, devido à limitação da assimilação de carbono pela atividade fotossintética dos vegetais. Diante disso, faz-se necessário o manejo do solo com tecnologias que possam reduzir a perda de água no solo e que amenize os efeitos do déficit hídrico às plantas de maracujazeiro-amarelo cultivadas em condições de semiaridez. Objetivou-se avaliar a aplicação no solo de doses de hidrogel e mulching sob os aspectos fisiológicos do cultivo de maracujazeiro-amarelo irrigado. O experimento foi desenvolvido em delineamento em blocos casualizados, no esquema fatorial 5 × 2, referente às cinco doses de hidrogel (0,0, 0,5, 1,0, 1,5 e 2,0 g dm−3 de solo) no solo sem e com cobertura vegetal oriunda braquiária (Brachiaria decumbens L.). As variáveis analisadas foram índices de clorofila, fluorescências (inicial, máxima e variável) e trocas gasosas. O índice de clorofila total foi elevado com a aplicação de 1,5 g dm−3 e uso de mulching, ao se aplicar doses de 2,0 g dm−3 de hidrogel a taxa fotossintética das plantas de maracujazeiro-amarelo aumentou, já a taxa de transpiração das plantas foi incrementada com o uso de cobertura vegetal e doses de hidrogel, como consequência houve redução na eficiência do uso da água.

ABSTRACT In the Brazilian semi-arid region, water deficit is one of the main factors that compromise the growth and productive yield of crops, including yellow passion fruit, due to the limitation of carbon assimilation by the photosynthetic activity of plants. Therefore, it is necessary to manage the soil with technologies that can reduce the loss of water in the soil and mitigate the effects of water deficit on yellow passion fruit plants cultivated under semi-arid conditions. The objective of this study was to evaluate the application of hydrogel doses and mulching to the soil on the physiological aspects of irrigated yellow passion fruit cultivation. The experiment was carried out in a randomized block design, in a 5 × 2 factorial scheme, referring to five doses of hydrogel (0.0, 0.5, 1.0, 1.5 and 2.0 g dm−3 of soil) in soil without and with mulching from signal grass (Brachiaria decumbens L.). The variables analyzed were chlorophyll indices, fluorescence (initial, maximum and variable) and gas exchange. The total chlorophyll index was increased with the application of 1.5 g dm−3 of hydrogel and the use of mulching; when applying hydrogel doses of 2.0 g dm−3 the photosynthetic rate of yellow passion fruit plants increased, whereas their transpiration rate increased with the use of mulching and doses of hydrogel; as a consequence, there was a reduction in water use efficiency.

RESUMEN La ingeniería de tejidos involucra el uso de células cultivadas en andamios con adiciones de factores de crecimiento para facilitar la proliferación celular. Su uso en trasplantes implica riesgo de infección bacteriana. La contribución actual describe la preparación y evaluación antibacteriana de un hidrogel a base de quitosano físicamente reticulado con poli (l-láctico-co-ɛ-caprolactona) (PLCL) enriquecido con nanopartículas de óxido de zinc (NP de ZnO) y oligoelementos (potasio y magnesio). El material se desarrolló como un andamio con propiedades antibacterianas. El quitosano y el PLCL son materiales de soporte biocompatibles aplicados en medicina para la reparación y regeneración de tejidos dañados, propiedades promovidas por las NP´s de ZnO y los oligoelementos antes mencionados. Las NP de ZnO se elaboraron mediante coprecipitación química. Los materiales se caracterizaron por DRX, FT-IR y SEM. Las pruebas antibacterianas se realizaron con cepas de Escherichia coli y Staphylococcus aureus por el método de KirbyBauer de acuerdo con las guías NCCLS y CLSI. Se pudo obtener un hidrogel homogéneo con adecuada morfología y distribución de elementos. El hidrogel con 300 mM de NP ZnO y oligoelementos mostró halos de inhibición antibacteriana de 13 mm para S. aureus y 19 mm para E. coli. Este biomaterial innovador con oligoelementos es prometedor para la ingeniería de tejidos al considerar el desafío de la infección bacteriana.

ABSTRACT Tissue engineering involves anchorage-dependent cells cultured on scaffolds, with growth factors added to facilitate cell proliferation. Its use in transplants implies the risk of bacterial infection. The current contribution describes the preparation and antibacterial evaluation of a chitosan-based hydrogel physically cross-linked with poly(l-lactic-coɛ-caprolactone) (PLCL) and enriched with zinc oxide nanoparticles (ZnO NPs) and trace elements (potassium and magnesium). The material was developed as a scaffold with built-in antibacterial properties. Chitosan and PLCL are biocompatible support materials applied in medicine for the repair and regeneration of damaged tissues, objectives promoted by ZnO NPs and the aforementioned trace elements. The ZnO NPs were elaborated by chemical coprecipitation. The materials were characterized by XRD, FT-IR, and SEM. Antibacterial testing was performed with strains of Escherichia coli and Staphylococcus aureus by the Kirby-Bauer method, in accordance with the NCCLS and CLSI guidelines. It was possible to obtain a homogeneous hydrogel with adequate morphology and distribution of elements. The hydrogel with 300 mM of Mg, K, and ZnO NP’s showed antibacterial inhibition halos of 13 mm for S. aureus and 19 mm for E. coli. This innovative biomaterial with trace elements holds promise for tissue engineering by considering the challenge of bacterial infection.

RESUMEN: Los viveros forestales que producen seedlings de especies nativas deben poner a disposición una alta diversidad forestal para satisfacer las demandas de los proyectos de recuperación. De esta forma, comprender el comportamiento de las diferentes especies y mejorar la tecnología de producción califica el manejo y reduce las pérdidas. Por lo tanto, se estudió el efecto de la adición de polímero hidroretenedor al sustrato sobre el desempeño de tres especies nativas cultivadas en condiciones de vivero. El diseño experimental fue completamente al azar con un esquema factorial. Se investigaron rasgos de supervivencia, morfológicos y fisiológicos en plántulas. En general, se observó que las especies estudiadas resultaron aptas para la técnica de trasplante con alta supervivencia a pesar de la influencia negativa del hidrogel sobre esta variable en las plántulas. Por otro lado, el uso de polímero hidroretenedor mejoró el crecimiento en altura, diámetro del tallo y la calidad de estas plántulas, demostrando ser una estrategia viable en la producción de seedlings nativas en un vivero.

SUMMARY: Forest nurseries that produce native species seedlings need to make heigh forestry diversity available to supply the demands of forest ecosystem recovery projects. In this way, understanding the behavior of different species and improving production technology improve management and reduce losses. We here studied the effect of the water-retaining polymer addition to the substrate on the performance of three native species grown under nursery conditions. The experimental design was completely randomized with a factorial scheme. Survival, morphological and physiological attributes of seedlings were investigated. In general, it was observed that studied species proved to be suitable for the subculturing technique, with high survival despite of hydrogel negative influence on this variable in seedlings. On the other hand, the use of water-retaining polymer improved growth in height, stem diameter and seedlings quality, demonstrating to be a viable strategy in native seedlings production in a nursery.

ABSTRACT Potato cultivation requires fertilizers to sustain crop yields, but a significant percentage of added nutrients is lost by leaching. The use of coating materials for fertilizers is currently being considered to reduce these losses. The objective of this study was to determine if a carrageenin based hydrogel (CBH), used to coat fertilizer, decreases NH4 + and K+ leaching from a potato crop without affecting growth, specific gravity, and tuber yield. The CBH was tested in a diploid potato crop, cultivar Criolla Colombia (Solanum tuberosum L., Phureja Group) using a randomized full block design including the treatments noncoated fertilizer (T1), CBH coated fertilizer (T2), and no fertilizer (T3). Mineral nutrients in soil leachates together with dry biomass, foliar area, chlorophyll, tuber specific gravity, and yield were quantified. The nutrient content in leachates from T2 were below those from T1. No significant differences between treatments were observed for growth factors, yield, and tuber specific gravity. This study confirms the controlling effect of the CBH, ensuring the retention of the nutrients added in the fertilizer and preventing them from easily leaching. Future field studies are worthwhile to establish the amount of fertilizer this coating could save.

RESUMEN El cultivo de papa requiere fertilizantes para mantener su rendimiento. Sin embargo, un porcentaje significativo de los nutrientes anadidos se lixivia. Actualmente el uso de materiales de recubrimiento para los fertilizantes se está considerando para disminuir estas pérdidas. El objetivo de este estudio fue determinar si un hidrogel a base de carragenina (CBH, por sus siglas en inglés), utilizado para recubrir el fertilizante aplicado, puede disminuir la lixiviación de NH4+ y K+ en un cultivo de papa, sin afectar el crecimiento, gravedad específica y el rendimiento de tubérculo. El CBH se probó en un cultivo de papa diploide, cultivar Criolla Colombia (Solanum tuberosum L., Grupo Phureja) utilizando un diseno de bloques completos al azar. Se evaluaron los tratamientos: fertilizante sin recubrimiento (T1), fertilizante recubierto con CBH (T2) y sin fertilizante (T3). Se cuantificaron los nutrientes minerales en los lixiviados junto con biomasa seca, área foliar, clorofila, gravedad específica del tubérculo y rendimiento. Los conteni-dos de nutrientes en los lixiviados de T2 fueron inferiores a los de T1, y no se observaron diferencias entre estos tratamientos para factores de crecimiento, rendimiento y gravedad específica. Los resultados evidencian que el CBH tiene potencial como material de recubrimiento para fertilizantes en papa y, se debe complementar con otros ensayos para determinar la cantidad de fertilizante que este recubrimiento podría ahorrar.

Resumo As argamassas são compósitos heterogêneos cujo ganho de resistência ocorre por meio de uma sucessão de reações químicas entre a água e o cimento Portland. Nesse sentido, polímeros hidrofílicos capazes de absorver água e liberá-la posteriormente vêm sendo desenvolvidos para melhorar as propriedades das argamassas. Assim, hidrogel à base de poliacrilamida, carboximetilcelulose e nanoargila foi sintetizado e aplicado em argamassas cimentícias preparadas com diferentes relações água/cimento (a/c = 0,40, 0,48 e 0,50). A sua aplicação nas argamassas reduziu o índice de consistência e a taxa de exsudação, e não ocasionou variação na densidade no estado endurecido destas. Já os índices de absorção de água das argamassas com hidrogel com a/c= 0,40 e 0,50 reduziram cerca de 6,1% e 6,7%, respectivamente. Esse mesmo comportamento também foi observado para a resistência à compressão. Em suma, o desenvolvimento e aplicação de hidrogéis capazes de absorver e liberar água é uma área bastante promissora para a construção civil.

Abstract Mortars are heterogeneous composites that gain strength through a succession of chemical reactions between water and Portland cement. In this sense, hydrophilic polymers that can absorb water and release it later have been developed to improve their properties. Thus, a hydrogel-based on polyacrylamide, carboxymethylcellulose and nanoclay was synthesized and applied in cement mortars prepared with different water/cement (w/c) ratios (0.40, 0.48, and 0.50). Its application in mortars reduced the consistency index and the exudation rate and did not cause variation in density in the hardened state. The water absorption rate of mortars with hydrogel with w/c= 0.40 and 0.50 reduced ~6.1% and 6.7%, respectively. This same behavior was also observed for compressive strength. In summary, the development and application of hydrogels capable of absorbing and releasing water is a very promising area for civil construction.