RESUMEN
This study was carried out to evaluate the effects of foliar sprays containing boron (B) nano-fertilizer (NF) on the growth and physiology of lettuce (Lactuca sativa) and zucchini (Cucurbita pepo). Plants were grown under greenhouse conditions for 60 days on a modified Hoagland solution with the presence and absence of boron (+B or -B). A synthesized B-NF foliar spray and a commercial B foliar fertilizer (Bortrac™ 150, BT) was applied at a concentration of 30 mg B L-1 at 10-d intervals throughout the experiment. The B-NF treatment increased the growth of lettuce 2.7- and 1.9-fold for shoots and roots, respectively, with an average production of lettuce biomass by ~58%. Similarly, the NF increased the growth of zucchini by 18 and 66% compared with Control-B (the absence of B), and 13 and 36% compared with BT, both for shoots and roots, respectively. Nevertheless, NF + B mostly decreased lettuce growth with symptoms of B toxicity in leaves. In lettuce, addition of B did not affect concentrations of phenols; however, in zucchini, Control-B induced a higher production of phenolic compounds possibly related to B deficiency. The B addition in lettuce reduced the DPPH activity by 32 and 21% in NF and BT, respectively, compared to Control-B. These responses were similar in zucchini; however, the effect of B was product of its presence in mineral solution rather than due the foliar product applied. This suggests that a NF-based delivery system for B may be highly effective at boosting plant productivity on B-limited soils.
Asunto(s)
Boratos , Compuestos de Calcio , Cucurbita , Fertilizantes , Lactuca , Nanopartículas , Boratos/química , Compuestos de Calcio/química , Cucurbita/metabolismo , Lactuca/metabolismo , Nanopartículas/química , Hojas de la Planta/metabolismo , Raíces de Plantas/metabolismoRESUMEN
OBJECTIVES: This study was conducted to establish a method for early, quick and cheap screening of iron excess tolerance in rice (Oryza sativa L.) cultivars. RESULTS: Based on the experiments, iron excess leads to reduction in shoot length (SL) and this can be a useful characteristic for adequate screening of tolerant genotypes. The sensitive genotypes Nipponbare and BR-IRGA 409 indicated higher accumulation of iron in their tissues while BRS-Agrisul and Epagri 108 also accumulated iron, but at lower concentrations. BR-IRGA 410 displayed an intermediate phenotype regarding iron accumulation. No changes in shoot Cu content can be observed when comparing treatments. On the other hand, an increase was seen for Zn and Mn when shoots are subjected to Fe2+ excess. Fe stress at a lower concentration than 7 mM increased Zn but decreased Mn contents in shoots of BR-IRGA 409. Strong positive correlations were found here for Fe × Zn (0.93); Fe × Mn (0.97) and Zn × Mn (0.92), probably due to the Fe-induced activation of bivalent cation transporters. Results show that genotypes scored as sensitive present higher concentration of Fe in shoots and this is an efficient method to characterize rice cultivars regarding iron response.
Asunto(s)
Adaptación Fisiológica/genética , Pruebas Genéticas , Hierro/toxicidad , Oryza/genética , Oryza/fisiología , Adaptación Fisiológica/efectos de los fármacos , Genotipo , Oryza/efectos de los fármacos , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/fisiología , Brotes de la Planta/efectos de los fármacos , Brotes de la Planta/fisiologíaRESUMEN
Plant responses to abiotic stress include various modifications in amino acid metabolism. By using a hydroponic culture system, we systematically investigate modification in amino acid profiles and the proteome of Arabidopsis thaliana leaves during initial recovery from low water potential or high salinity. Both treatments elicited oxidative stress leading to a biphasic stress response during recovery. Degradation of highly abundant proteins such as subunits of photosystems and ribosomes contributed to an accumulation of free amino acids. Catabolic pathways for several low abundant amino acids were induced indicating their usage as an alternative respiratory substrate to compensate for the decreased photosynthesis. Our results demonstrate that rapid detoxification of potentially detrimental amino acids such as Lys is a priority during the initial stress recovery period. The content of Pro, which acts as a compatible osmolyte during stress, was adjusted by balancing its synthesis and catabolism both of which were induced both during and after stress treatments. The production of amino acid derived secondary metabolites was up-regulated specifically during the recovery period, and our dataset also indicates increased synthesis rates of the precursor amino acids. Overall, our results support a tight relationship between amino acid metabolism and stress responses.
Asunto(s)
Aminoácidos/metabolismo , Arabidopsis/fisiología , Estrés Fisiológico , Proteínas de Arabidopsis/metabolismo , Deshidratación , Lisina/metabolismo , Estrés Oxidativo , Hojas de la Planta/metabolismo , Prolina/metabolismo , Proteoma/metabolismo , Estrés SalinoRESUMEN
Farmers of the Franca region in Brazil observed that Bidens sulphurea was able to eliminate the Panicum maximum weed, which infected coffee plantations, without affecting the crop. In an effort to determine if the inhibitory effects observed were due to the presence of phytotoxic compounds from leaves and roots, a biodirected isolation and spectroscopic characterization has been carried out. The leaf dichloromethane and root acetone extracts were the most active, and the former appeared to be more phytotoxic to the target species, including four weeds. A total of 26 compounds were isolated from leaves and roots, and four of them are described here for the first time. The major compounds in the leaf extract are the sesquiterpene lactones costunolide, reynosin, and santamarine, and these showed marked inhibition. Amaranthus viridis and Panicum maximum were the most sensitive species of the weeds tested. These three phytotoxic lactones were also evaluated on A. viridis and P. maximum under hydroponic conditions. A. viridis was the most affected species with the three lactones, and santamarine was the most phytotoxic compound on both. This is the first time that the phytotoxicity of sesquiterpene lactones has been evaluated on hydroponic culture. The work described here is a preliminary approach for the use of B. sulphurea for weed control in agriculture, both as a cover crop and by use of its components as natural herbicide leads.
Asunto(s)
Bidens/química , Herbicidas/toxicidad , Extractos Vegetales/toxicidad , Malezas/efectos de los fármacos , Amaranthus/efectos de los fármacos , Asteraceae/efectos de los fármacos , Brasil , Herbicidas/química , Herbicidas/aislamiento & purificación , Estructura Molecular , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Hojas de la Planta/química , Raíces de Plantas/química , Control de MalezasRESUMEN
Less than 0.5% of total water in the world is available for human consumption and agriculture. The major part of the world's water is saline and salinity in soils interferes in germination of seeds and the posterior development of the plant. In order to increase the osmotolerance of tomato, seedlings were associated with Azospirillum brasilense Cd, Azospirillum brasilense Cd transformed bacteria with a plasmid harboring a trehalose biosynthesis gene-fusion or Chlorella vulgaris. Two plant culture media: Hydroponic and Murashige and Skoog were tested. In the first set of studies seedlings were associated to single free cells meanwhile in a second set single and combined free cells were studied. A positive interaction between transformed Azospirillum and Chlorella vulagris and tomato plants was observed. Seedlings showed a salt concentration tolerance, as sodium chloride, up to 200 mM. According to our results, the association of plants with A. brasilense Cd-BIF and C. vulgaris is a viable approach to increase their salt tolerance and biomass, as consequence the possible use of sea water to irrigate horticultural plants.
Asunto(s)
Azospirillum brasilense/crecimiento & desarrollo , Chlorella vulgaris/crecimiento & desarrollo , Presión Osmótica , Salinidad , Plantones/microbiología , Solanum lycopersicum/microbiología , Medios de Cultivo/química , Solanum lycopersicum/fisiología , Plantones/fisiologíaRESUMEN
Less than 0.5% of total water in the world is available for human consumption and agriculture. The major part of the world's water is saline and salinity in soils interferes in germination of seeds and the posterior development of the plant. In order to increase the osmotolerance of tomato, seedlings were associated with Azospirillum brasilense Cd, Azospirillum brasilense Cd transformed bacteria with a plasmid harboring a trehalose biosynthesis gene-fusion or Chlorella vulgaris. Two plant culture media: Hydroponic and Murashige and Skoog were tested. In the first set of studies seedlings were associated to single free cells meanwhile in a second set single and combined free cells were studied. A positive interaction between transformed Azospirillum and Chlorella vulagris and tomato plants was observed. Seedlings showed a salt concentration tolerance, as sodium chloride, up to 200 mM. According to our results, the association of plants with A. brasilense Cd-BIF and C. vulgaris is a viable approach to increase their salt tolerance and biomass, as consequence the possible use of sea water to irrigate horticultural plants.
Asunto(s)
Azospirillum brasilense/crecimiento & desarrollo , Chlorella vulgaris/crecimiento & desarrollo , Solanum lycopersicum/microbiología , Presión Osmótica , Salinidad , Plantones/microbiología , Medios de Cultivo/química , Solanum lycopersicum/fisiología , Plantones/fisiologíaRESUMEN
Less than 0.5% of total water in the world is available for human consumption and agriculture. The major part of the world's water is saline and salinity in soils interferes in germination of seeds and the posterior development of the plant. In order to increase the osmotolerance of tomato, seedlings were associated with Azospirillum brasilense Cd, Azospirillum brasilense Cd transformed bacteria with a plasmid harboring a trehalose biosynthesis gene-fusion or Chlorella vulgaris. Two plant culture media: Hydroponic and Murashige and Skoog were tested. In the first set of studies seedlings were associated to single free cells meanwhile in a second set single and combined free cells were studied. A positive interaction between transformed Azospirillum and Chlorella vulagris and tomato plants was observed. Seedlings showed a salt concentration tolerance, as sodium chloride, up to 200 mM. According to our results, the association of plants with A. brasilense Cd-BIF and C. vulgaris is a viable approach to increase their salt tolerance and biomass, as consequence the possible use of sea water to irrigate horticultural plants.
Asunto(s)
Azospirillum brasilense/crecimiento & desarrollo , Chlorella vulgaris/crecimiento & desarrollo , Solanum lycopersicum/microbiología , Presión Osmótica , Salinidad , Plantones/microbiología , Medios de Cultivo/química , Solanum lycopersicum/fisiología , Plantones/fisiologíaRESUMEN
El objetivo del presente estudio fue evaluar la calidad bacteriológica de lechugas comercializadas en el Área Metropolitana de San José, Costa Rica y cultivadas de diversas maneras, con el fin de discernir diferencias entre los métodos de cultivo y el riesgo a la Salud Pública que estos productos pueden representar. El estudio se llevó a cabo en el Laboratorio de Microbiología de Alimentos de la Facultad de Microbiología, Universidad de Costa Rica, durante los meses de marzo a julio, 2010. Se analizaron 30 muestras de lechuga (10 cultivadas por el método tradicional, tradicional, 10 de cultivo orgánico y 10 producidas mediante hidroponía). Cada muestra fue adquirida en supermercados donde se certifica el origen de las mismas. A cada muestra se le determinó el recuento total de aerobios mesófilos aerobio, recuento de coliformes totales, fecales y de Escherichia coli, así como la presencia/ausencia en 25 g de Salmonella spp. y Listeria monocytogenes. Los resultados obtenidos demuestran que no existe una diferencia, estadísticamente significativa (p>0,001) entre los diferentes tipos de cultivo para ninguno de los parámetros evaluados. Un porcentaje importante de las muestras presentó colifomes, no obstante, únicamente se aisló una cepa de Escherichia coli, a partir de una lechuga cultivada de manera tradicional. Se logró aislar cuatro cepas de Salmonella spp así como una cepa de Listeria monocytogenes. Los datos obtenidos permiten evidenciar el hecho de que el consumo del producto crudo y sin una adecuada limpieza y desinfección representa un riesgo para la salud del consumidor, así como que no existe, desde el punto de vista bacteriológico, una diferencia significativa entre el cultivo tradicional, orgánico e hidropónico de la lechuga, lo que hace suponer que no se siguen los lineamientos específicos de cada tipo de cultivo, o se da un mal manejo y contaminación post cosecha en los productos.
The main objective of this work was to evaluate the microbiological quality of lettuces commercialized in the Metropolitan Area of San José, Costa Rica, and cultured in different ways, in order to detect differences between the culturing methods and the risk that these products may represent for Public Health. The study was done at the Food Microbiology Laboratory, Universidad de Costa Rica, from March to July, 2010. 30 lettuce samples were analyzed (10 obtained by traditional culture, 10 by organic culture and 10 by hydropony). All samples were obtained from markets where their origin was certified. Total aerobic plate count, total and fecal coliforms count and Escherichia coli were determined to all samples, as well as the presence/abscense of Salmonella spp. and Listeria monocytogenes in 25 g. Results obtained show that there is no statistically significant difference (pE. coli strain was isolated from a traditionally cultured lettuce sample. Four different Salmonella spp. strains were isolated from the samples as well as one Listeria monocytogenes strain. Data obtained show that the consumption of this product, raw or without an adequate hygiene and disinfection may represent a risk for health. Also, from the bacteriological point of view, there is no significant difference between the culturing methods evaluated, suggesting that the specific directions for each type of culture are not followed or that there is an inadequate handling of the products or post harvest contamination.