Do sub-doses of glyphosate and 2,4-D cause hormesis in the pineapple plants? Insights into the response of the pineapple plants to this phenomenon

The slow growth of the pineapple (Ananas comosus (L.) Merr.) during the vegetative phase prolongs the crop cycle, resulting in higher production costs. When used in low doses, some herbicides can stimulate plant growth, a phenomenon known as hormesis. The aim of this study was to determine the effects of sub-doses of glyphosate and 2,4-dichlorophenoxyacetic acid (2,4-D) on growth in the Pérola cultivar of the pineapple. The treatments under study consisted of glyphosate applications of 0, 1.8, 3.6, 7.2, 18, 36, 72, 180, 360 and 720 g a.e. ha-1, and 2,4-D applications of 0, 1.68, 3.35, 6.70, 16.75, 33.5, 67, 167.5, 335 and 670 g a.e. ha-1. The experiments were completely randomised with four replications. The plants were grown in the greenhouse in pots with a capacity of 8 dm3 substrate. Growth variables were evaluated in the plants, together with the total and partitioned accumulated biomass (leaf, stem and root). The data were submitted to analysis of variance and regression. The pineapple showed greater phytotoxicity from the glyphosate herbicide at applications ranging from 18 to 720 g a.e. ha-1 and from 2,4-D in the range of 167.5 to 670 g a.e. ha-1. The hormesis effect was evidenced by the 32.25% increase in root fresh weight at the dose of 1.8 g a.e. ha-1 glyphosate. However, the slow growth of the pineapple was not overcome by the hormesis effect of the herbicides.The slow growth of the pineapple (Ananas comosus (L.) Merr.) during the vegetative phase prolongs the crop cycle, resulting in higher production costs. When used in low doses, some herbicides can stimulate plant growth, a phenomenon known as hormesis. The aim of this study was to determine the effects of sub-doses of glyphosate and 2,4-dichlorophenoxyacetic acid (2,4-D) on growth in the Pérola cultivar of the pineapple. The treatments under study consisted of glyphosate applications of 0, 1.8, 3.6, 7.2, 18, 36, 72, 180, 360 and 720 g a.e. ha-1, and 2,4-D applications of 0, 1.68, 3.35, 6.70, 16.75, 33.5, 67, 167.5, 335 and 670 g a.e. ha-1. The experiments were completely randomised with four replications. The plants were grown in the greenhouse in pots with a capacity of 8 dm3 substrate. Growth variables were evaluated in the plants, together with the total and partitioned accumulated biomass (leaf, stem and root). The data were submitted to analysis of variance and regression. The pineapple showed greater phytotoxicity from the glyphosate herbicide at applications ranging from 18 to 720 g a.e. ha-1 and from 2,4-D in the range of 167.5 to 670 g a.e. ha-1. The hormesis effect was evidenced by the 32.25% increase in root fresh weight at the dose of 1.8 g a.e. ha-1 glyphosate. However, the slow growth of the pineapple was not overcome by the hormesis effect of the herbicides

Physiological quality in maize seeds using conventional methods and NIR spectroscopy

Maize is one of the most important cereals, and stands out for its wide genetic diversity, adaptation to the most diverse climate conditions, and being, both directly and indirectly, the most basic food source of man. Globally, production is dependent on seed quality. Known methodologies for evaluating seed quality require improvement in developing technologies capable of achieving, in less time, results for the targets under evaluation. The aim of this study, therefore, was to compare conventional vigour testing with the ability of NIR technology to classify the physiological quality of maize seeds, cv. DKB-290-HS. For the experiment, which was conducted in a completely randomised design (CRD), six Batches of 200 seeds were used, with four replications. Conventional methods of evaluating seed vigour were used in the study. For the evaluation using the near-infrared (NIR) method, the seeds were placed with the embryo facing the source of electromagnetic waves. The resulting spectra were analysed by the Pirouette software using the PLS-DA method. The conventional methods for vigour, and the NIR technique both efficiently detected the levels of physiological quality. NIR also revealed the differences between Batches, classifying the physiological quality of maize seeds, cv. DKB-290-HS, into different levels quickly and efficiently

Herbicide-induced hormesis and its effect on crop development

The beneficial effect of growth stimulation caused by low doses of a toxic product such as an herbicide, is due to the phenomenon known as hormesis. Plants affected by this phenomenon show changes in their metabolism and, as a result, are able to increase nutrient absorption and biomass accumulation. Various herbicides have been developed as growth regulators, proving the hormesis hypothesis. The most notable example is the product 2,4-D, originally developed as auxin. This phenomenon can bring benefits for crops, such as increased yield. However, for the technique to be applied in practice, information is still needed to support its potential application in agriculture. The aim of this review was to define the state of the art and measure the effect of the hormesis phenomenon of herbicides in agriculture. To carry out a bibliographical review using the following databases: SciELO, Scopus, Web of Science, Redalyc, EBSCO, and DOAJ. The quality of the studies was assessed using eligibility, inclusion and exclusion criteria, employing the following indexing terms: dichlorophenoxyacetic acid, herbicide subdose, herbicide toxicity, and growth regulator. Based on a summary of the studies identified via electronic or manual searches relating to the phenomenon of hormesis, it was found that the literature on the subject remains ambiguous, with no consensus regarding the real effects of the phenomenon on crop performance. This article further argues that the magnitude of the hormetic effect on crops depends on several factors, such as the subdose, the age of the plant, and other conditions

Interferencia de Cenchrus echinatus Y Rottboellia exaltata EN EL CRECIMIENTO DEL FRIJOL CAUPÍ

Cowpea is an important crop for the food security of the world population. However, their production is constantly affected by weed interferences. The objective of this research was to determine the effect of two different weeds at different densities of competition on the growth characteristics of the crop. The study was conducted using a randomized block design in a factorial arrangement of the treatments (2x4 for analysis in cowpea, and 2x3 for weeds). The weed species (Cenchrus echinatus and Rottboellia exaltata) and four competition densities (zero, two, four, and six individuals per pot), with four repetitions, were studied at the crop flowering stage. We measured leaf area, leaf and stem dry mass, root dry mass (RDM), dry mass of the aerial part (DMAP), total dry mass, and the ratio (RDM/DMAP); additionally, the dry mass of the aerial part and root (DMAW and DMRW) of the weeds was measured. The increase in the density of the weeds resulted in a decrease in the values of all the variables of the crop. In the case of weeds, C. echinatus showed higher DMAW than R. exaltata although there were no differences in DMRW. Both weeds negatively affect the growth of bean plants, though with C. echinatus the effect is even greater. The interference effect is higher as the density of the weeds increasesEl frijol caupí es un cultivo importante para la seguridad alimentaria de la población mundial; sin embargo, su producción es afectada constantemente por la interferencia de las malezas. El objetivo de esta investigación fue determinar el efecto de la interferencia de las malezas en diferentes densidades de competencia sobre las características de crecimiento del cultivo. El estudio fue conducido mediante diseño de bloques al azar en arreglo factorial 2x4 para análisis del cultivo y 2x3 para las malezas. Fueron estudiadas dos especies de maleza (Cenchrus echinatus y Rottboellia exaltata) y cuatro intensidades de competencia (cero, dos, cuatro y seis individuos por maceta), con cuatro repeticiones. Las evaluaciones fueron realizadas en la etapa de floración del cultivo y las variables medidas fueron área foliar, masa seca de las hojas, del tallo, de la raíz (MSR), de la parte aérea (MSPA), masa seca total y la relación MSR/MSPA. Además, fueron cuantificadas en las malezas la masa seca de la parte aérea (MSPAM) y de la raíz (MSRM). El aumento de la densidad de competencia de las malezas resultó en disminución de los valores de todas las variables analizadas en el cultivo. En las malezas, C. echinatus mostró mayor MSPAM que R. exaltata, aunque no hubo diferencias en MSRM. Ambas malezas afectan negativamente el crecimiento de las plantas de frijol, aunque con C. echinatus el efecto es aún mayor. El efecto de interferencia es mayor a medida que aumenta la densidad de las maleza

Organic fertilization for the beginning of sweet potato (Ipomoea batatas L.) cultivation in savanna soils

Debido a la limitada información sobre el cultivo de camote (Ipomoea batatas L.) en áreas silvestres de la sabana, el objetivo de este estudio fue determinar la dosis ideal y el tipo de fertilizante orgánico para el cultivo de camote en suelos de la sabana sin antecedentes de explotación. Se probaron diferentes dosis de fertilizantes en cuatro experimentos: estiércol de ganado (0, 10, 20, 30 y 40 t∙ha-1), pollinaza (0, 5, 10, 15 y 20 t∙ha-1), compost A (0, 0.75, 1.5, 2.25 y 3.0 t∙ha-1) y compost B (0, 0.75, 1.5, 2.25 y 3.0 t∙ha-1). El quinto experimento consistió en una prueba de eficiencia de fertilizantes orgánicos utilizando dosis recomendadas para el cultivo de camote, lo cual resultó en seis tratamientos: testigo (sin fertilización orgánica), estiércol de ganado (20 t∙ha-1), pollinaza (10 t∙ha-1), compost A (1.5 t∙ha-1), compost B (1.5 t∙ha-1) y compost C (0.375 t∙ha-1). En los primeros cuatro experimentos, los productos y dosis recomendadas se definieron en orden de eficiencia de producción: pollinaza (dosis entre 13 y 20 t∙ha-1) > estiércol de ganado (dosis entre 30 y 40 t∙ha-1) > compost B (dosis entre 0.75 y 2.25 t∙ha-1) = compost A (dosis entre 2.25 y 3.00 t∙ha-1). Con el quinto experimento se concluyó que: 1) la pollinaza fue el fertilizante inicial más adecuado para el cultivo de camote en suelos de la sabana y 2) el rendimiento del camote estuvo vinculado directamente a la masa de las raíces comerciales, el número de raíces comerciales y la productividad de tallos; las cuales, a su vez, fueron maximizadas al incrementar la materia orgánica y las cantidades de fósforo en el suelo.Revisión por pares

Seedlings production of two tomato (Solanum licopersicum L.) cultivars under different environments and substrates

The type of environment and substrates quality in seedlings production are essential for the production of productive plants under field conditions. In order to determine the best environment and substrate for seedlings production of two tomato cultivars (IPA 06 and Santamélia), two experiments, completely randomized and arranged in subdivided plots with five replicates, were conducted under the environmental conditions of Boa Vista, Roraima, Brazil. Treatments consisted of the association among five environments (A1 - greenhouse, A2 - Chromatinet ® 35% red, A3 - Chromatinet ® 50% red, A4 - Chromatinet ® 35% Silver and A5 - Chromatinet ® 50% Silver) and four substrates S1 - OrganAmazon®; S2 - OrganAmazon® + PureHumus®; S3 - OrganAmazon® + PureHumus® + soil + bovine manure, and S4- OrganAmazon® + PureHumus® + soil + manure + carbonized rice husk (CRH) on the following variables: number of leaves, plant height, stem diameter, dry shoot and root biomass, plant height/stem diameter ratio accordingly to colon & Dickson quality index of seedlings. Substrates made with the addition of PureHumus®, without presenting CRH (S2 and S3), which favored the increasing of all analyzed variables. In addition, greenhouse, especially when is associated to S2 substrate, had achieved the best environment for seedlings production of the two evaluated tomato cultivars. Photoconverter shading nets were not efficient in tomato seedlings production under climatic conditions of Boa Vista, Roraima, Brazil

Seedlings production of two tomato (Solanum licopersicum L.) cultivars under different environments and substrates

The type of environment and substrates quality in seedlings production are essential for the production of productive plants under field conditions. In order to determine the best environment and substrate for seedlings production of two tomato cultivars (IPA 06 and Santamélia), two experiments, completely randomized and arranged in subdivided plots with five replicates, were conducted under the environmental conditions of Boa Vista, Roraima, Brazil. Treatments consisted of the association among five environments (A1 - greenhouse, A2 - Chromatinet ® 35% red, A3 - Chromatinet ® 50% red, A4 - Chromatinet ® 35% Silver and A5 - Chromatinet ® 50% Silver) and four substrates S1 - OrganAmazon®; S2 - OrganAmazon® + PureHumus®; S3 - OrganAmazon® + PureHumus® + soil + bovine manure, and S4- OrganAmazon® + PureHumus® + soil + manure + carbonized rice husk (CRH) on the following variables: number of leaves, plant height, stem diameter, dry shoot and root biomass, plant height/stem diameter ratio accordingly to colon and Dickson quality index of seedlings. Substrates made with the addition of PureHumus®, without presenting CRH (S2 and S3), which favored the increasing of all analyzed variables. In addition, greenhouse, especially when is associated to S2 substrate, had achieved the best environment for seedlings production of the two evaluated tomato cultivars. Photoconverter shading nets were not efficient in tomato seedlings production under climatic conditions of Boa Vista, Roraima, Brazil.Objetivando determinar o melhor ambiente e substrato na produção de mudas de duas cultivares de tomate (IPA 06 e Santamélia), dois experimentos delineados inteiramente ao acaso e arranjados em parcelas subdivididas, com cinco repetições, foram desenvolvidos sob as condições de Boa Vista, Roraima, Brasil. Os tratamentos consistiram da associação entre cinco ambientes (A1 – estufa agrícola; A2 – Chromatinet® 35% vermelha; A3 – Chromatinet® 50% vermelha; A4 – Chromatinet® 35% Silver e A5 – Chromatinet® 50% Silver) e quatro substratos (S1 – OrganoAmazon®; S2 - OrganoAmazon® + PuroHumus®; S3 - OrganoAmazon® + PuroHumus® + solo + esterco bovino, e S4 - OrganoAmazon® + PuroHumus® + solo + esterco + casca de arroz carbonizada (CAC)) sobre as variáveis de crescimento e de qualidade das mudas. Substratos confeccionados com a adição de PuroHumus®, sem apresentar CAC (S2 e S3), favoreceram o incremento de todas as variáveis analisadas. Além disso, a estufa agrícola, principalmente quando associada ao substrato S2, foi o melhor ambiente para a produção de mudas das duas cultivares de tomate. Os telados com telas fotoconversoras não foram eficientes na produção de mudas de tomate sob as condições climáticas de Boa Vista, Roraima, Brasil.El tipo de ambiente y la calidad de los sustratos en la producción de plántulas son esenciales para la producción de plantas productivas bajo condiciones de campo. Con el objetivo de determinar el mejor ambiente y sustrato para la producción de plántulas de dos cultivares de tomate (IPA 06 y Santamélia), dos experimentos, completamente aleatorios y dispuestos en parcelas subdivididas con cinco repeticiones, se llevaron a cabo bajo las condiciones ambientales de Boa Vista, Roraima, Brasil . Los tratamientos consistieron en la asociación entre cinco ambientes (A1 - invernadero, A2 - Chromatinet ® 35% rojo, A3 - Chromatinet ® 50% rojo, A4 - Chromatinet ® 35% plata y A5 - Chromatinet ® 50% plata) y cuatro sustratos S1 - OrganAmazon®; S2 - OrganAmazon® + PureHumus®; S3 - OrganAmazon® + PureHumus® + estiércol del suelo + bovino, y S4- OrganAmazon® + PureHumus® + suelo + estiércol + cascarilla de arroz carbonizada (CRH) en las siguientes variables: número de hojas, altura de la planta, diámetro del tallo, brote seco y la biomasa de la raíz, la relación entre la altura de la planta y el diámetro del tallo de acuerdo con el índice de calidad de las plántulas de colon y Dickson. Los sustratos se hicieron con la adición de PureHumus®, sin presentar CRH (S2 y S3), lo que favoreció el aumento de todas las variables analizadas. Además, el invernadero, especialmente cuando está asociado al sustrato S2, había logrado el mejor ambiente para la producción de plántulas de los dos cultivares de tomate evaluados. Las redes de sombreado fotoconvertidor no fueron eficientes en la producción de plántulas de tomate en condiciones climáticas de Boa Vista, Roraima, Brasil

Environments and substrates for “pimenta-de-cheiro” (Capsicum chinense Jacq.) seedling production in the Amazon savana

Quality seedlings production is one of the most important steps in the cultivation of vegetable species. In this sense, the objective was to evaluate the influence of different environments and substrates on the production of “pimenta-de-cheiro” (Capsicum chinense Jacq.) seedlings in Boa Vista, Roraima. An experiment was installed in a completely randomized design (CRD), with treatmentsarranged in subdivided plots. Five environments were evaluated: AG - agricultural greenhouse; TV35 - red shading net with 35% shading (red ChromatiNet®); TV50 - red shading net with 50% shading (red ChromatiNet®); TP35 - silver shading net with 35% shading (ChromatiNet® silver) and TP50 - silver shading net with 50% shading (ChromatiNet® silver) and four substrates: O -OrganoAmazon®; OP - OrganoAmazon® and PuroHumus®; OPSE (OrganoAmazon®, PuroHumus®, soil and manure) and OPSEC (OrganoAmazon®, PuroHumus®, soil, manure and carbonized rice husk). On the TP35 and TP50 shading nets, the C. Chinense grown on the OP substrate showed high Dickson’s quality index (DQI). The combination agricultural greenhouse (EA) and OPSE substrate promoted superior quality Capsicum chinense seedlings. The substrates OPSEC and OPSE are more affordable alternatives for the production of Capsicum chinense seedlings. Shading nets, associated with the alternative substrates, do not favor the production of quality Capsicum chinense seedlings under Amazon savanna conditions

Tecnicas agronómicas prioritarias del camu-camu (Myrciaria dubia-Myrtaceae). Tres manuales para el productor: poda-defoliación, control del gorgojo del fruto y fertilización orgánica

Presenta tecnologías de manejo agronómico del camu-camu (Myrciaria dubia) con el objetivo de mejorar su productividad en las áreas inundables, fortaleciendo la agricultura rural y haciéndola sostenible para las familias que cultivan en este tipo de ecosistemas. Se explican diferentes tipos de poda para formación y fructificación, raleo de ramas y de plantas, defoliación, riego, fertirriego, fertilización orgánica/mineral y manejo integrado de plagas. Todas técnicas que han demostrado ser viables porque no demandan altos costos y son amigables con el ambiente. Este manual da a conocer una serie de técnicas para apoyar la producción orgánica del camu-camu, acercando al productor a las formas de preparación de los productos y la aplicación de técnicas innovadoras, de manera práctica y sencilla, a fin de mejorar la rentabilidad y sostenibilidad de sus parcelas