Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Con la finalidad de ampliar el conocimiento respecto a la estructura vegetativa y condiciones ambientales, dos zonas costeras (norte y sur) en el estado de Sonora, México, donde se desarrolla en forma natural Salicornia bigelovii fueron investigadas. Basados en la abundancia de Salicornia, tres localidades fueron seleccionadas en las dos zonas. Transectos en cada uno de las tres localidades fueron desarrollados. Los sedimentos en las áreas de la zona norte mostraron valores superiores en comparación de las del sur del estado en materia orgánica. La biomasa vegetal, densidad, la altura y la frecuencia de ocurrencia fueron mayores en las regiones frecuentemente inundadas en comparación de las regiones poco o menos frecuentemente por las mareas. La biomasa total promedio varió desde 2.23 hasta 6.33 kg (peso seco) m-2 y se compone sobre todo de los componentes de la superficie. Los valores máximos de biomasa de Salicornia se observaron en febrero a mayo en ambas zonas. El crecimiento de Salicornia bigelovii está influenciada principalmente por la frecuencia de las inundaciones, la duración de la exposición a la atmósfera durante la marea baja, las precipitaciones, la salinidad y el contenido de sal del agua del ambiente y los sedimentos, respectivamente. El contenido de carbono aumentó con la edad de la planta, mientras que el contenido de proteína disminuye en un 233.6 %. El aumento constante de la presión antropogénica sobre las zonas costeras donde se desarrolla Salicornia y otras halófitas obligadas, requieren un ordenamiento de protección inmediato para evitar vulnerabilidad en sus poblaciones.

The insecticidal activity of Cassia sieberiana (DC) and Vernonia amygdalina (Del.) aqueous extract against Callosobruchus maculatus (F.) in treated bambara groundnut was evaluated under laboratory conditions (25 – 29°C and 56 – 70% r.h.). Seeds were treated separately at four concentrations (2, 4, 6 and 8 ml/100g of seeds) of both plants aqueous extracts. Pirimiphos methyl applied at 8 mg a.i./kg was included as positive control. Data collected were adult mortality, number of adult progeny  (F1 and F2), percentage seed damage, percentage weight loss and germination capacity. Results showed that increasing concentration of both plant extracts and period of exposure to treated seeds significantly (P<0.05) increased adult mortality levels from 16.9±2.9 to 100%. Furthermore, both plant extracts applied at 8 ml/100 g of seeds were comparable to pirimiphos-methyl after 96 h of exposure. The plant extracts significantly (P<0.05) reduced number of adult progeny, percentage seed damage and percentage weight loss, which all progressively declined with increasing concentration from 2 to 8 ml. Both plant aqueous extracts had no effect on germination capacity of treated seeds. For all the parameters measured, the plant extracts tested showed significantly higher biological activity in treated seeds compared to the untreated control. The present results suggest that these plant aqueous extracts have the potential to control C. maculatus populations in stored bambara groundnut.  

The use of appropriate spacing when planting large crops is a technology that can be very easily applied, and that can result in a significant increase in yield. The aim of this work was to estimate the best spacing between rows in the Castor Bean cv. ‘BRS Energia’ (Ricinus communis L.), with a view to optimising maximum yield. The experiment was carried out on the Juá farm, in Itatuba, in the State of Paraíba, Brazil, in the 2015 agricultural year. The experimental design was of randomised blocks, with four replications and six treatments of different spacing between rows (0.5, 0.75, 1.0, 1.25, 1.50 and 1.75 m). Values for plant height, stem diameter, number of racemes and yield were determined at the end of the crop cycle. Reducing the spacing promoted an increase in plant height. At the smallest spacing, plants reached heights of more than 2.0 m. At the larger spacings, the plants achieved greater stem diameter and number of racemes. The highest yield was obtained at the two smallest spacings, where yields of more than 2000 kg ha-1were achieved.

The pods of trees from tropical deciduous forest are relevant in the dry season due to their high availability. Whole pods from seven plant species Acacia pennatula (Schltdl. & Cham.) Benth., Caesalpinia gaumeri (Britton & Rose) Greenm., Leucaena leucocephala (Lam.) de Wit, Lysiloma latisiliquum (L.) Benth., Mimosa bahamensis Benth., Piscidia piscipula (L.) Sarg. and Senegalia gaumeri (S. F. Blake) Britton & Rose which are reported as consumed by small ruminants were evaluated. Their nutritional value, phenolic compounds, in vitro dry matter (IVDMD) and organic matter digestibility (IVOMD) and metabolizable energy (ME) with and without the inclusion of polyethylene glycol (PEG) were evaluated. The pods from P. piscipula showed the highest crude protein content. The pods of L. leucocephala, C. gaumeri, and A. pennatula resulted with the highest IVDMD (46.3 and 44.5%), IVOMD (44.8 and 45.4%) and ME (6.8 and 6.7 MJ) (P<0.05). The phenolic compounds were not detected in C. gaumeri, L. latisiliquum and S. gaumeri pods. The IVDMD, IVOMD and ME of L latisiliquum and P. piscipula pods (P<0.05) was lower when PEG was added. Pods from A. pennatula, C. gaumeri and L. leucocephala showed acceptable nutritional value for their use as supplement for ruminants.

The fruiting potential of advanced cotton cultivars is not a limiting factor for achieving yield targets but retention of squares and flowers for successful maturation into bolls is major challenge. In this article, we focused on why shedding occurs, its mechanism, yield losses, plant self-compensation, effects on plant growth and possible management to ameliorate its adverse effects. We concluded that it is quite unfair to blame single factor, instead it is an integrated effect of plant and stress factors i.e., high temperature, drought, thick plant stand, insects and diseases etc. contribute to accelerate shedding which ranges about 40-50%. The stresses induce the excessive production of degrading enzymes like pectinase, cellulose and hydrolase, while ethylene and abscisic acid is produced excessively to hasten the degradation process for shedding. The physiological disturbance contributes 7-35 and 42-64% abscission of unopened flowers and bolls, respectively. The square and flower are more frequent to shedding at high temperature compared to immature bolls. The flowers and boll shedding up to 30% is tolerable limit because cotton can recover yield provided weather support the crop later in season. The self-regulated abscission of floral parts is not easy to control under field conditions, however, the adverse effects of stress mediated shedding can be ameliorated with girdling and avoiding pest and stressful conditions, application of plant growth regulator (PGR) to control vegetative growth  and abscisic acid (abscission promoter) and ethylene inhibitors like naphthalene acetic acid, silver thiosulfate and 1-methylcyclopropene.

Soil organic carbon and carbon stock influence, directly or indirectly, most of soil aggregate stability indicators. The objective of this study was to quantify the production of dry biomass (DB), total organic carbon (TOC) and carbon stock (CStk) in soil, and to evaluate their influence on some indicators of aggregation in an Oxisol at a Cerrado biome in Uberaba-MG, Brazil. The design was completely randomized blocks, in two evaluation periods: three and six cuts, at six depths (0-0.1, 0.1-0.2, 0.2-0.3, 0.3-0.4, 0.4-0.5 and 0.5-0.6 m). It was evaluated: soil density (SD), volumetric humidity (VH), aggregate stability index (AEI), weighted mean diameter (WDA), mean diameter (GDA), index of aggregates with diameter greater than 2 mm (AI) and sensitivity index (SI), replicated by 4. The best AEI of the soil and the highest TOC contents were found in the most superficial layers, 0 to 0.2 m, for both cuttings. The greater values of TOC and CStk, occurred at the sixth cut area, where there was a higher amount of DB on soil surface. The higher levels of organic matter did not provide higher AEI in the area of sixth cut, when compared to that of the third cut. The TOC and CStk levels in both areas generally had a positive influence on soil aggregation indicators for both cuts.

Porcine proliferative enteropathy (PPE) is an economically important, transmissible infectious disease of worldwide dis­tribution caused by Lawsonia intracellularis. The objective of this report is to describe a case of PPE caused by L. intracel­lularis in coinfection with Trichuris suis and Balantidium coli in Uruguay. The disease was diagnosed in October 2015 in a herd of 130 crossbred grower pigs up to 3 months of age. The cumulative incidence was 14% (18/130) and a lethality rate 83% (15/18). Affected animals presented profuse diarrhea, ill thrift and weakness, with progression to death after a clinical course of 10 days. At necropsy of one pig, the terminal segment of the ileum, cecum and colon showed thickening of the mucosa and irregular folds in a cerebriform pattern. In the cecum and prox­imal colon, there was also a diffuse fibrinonecrotic membrane attached to the mucosa with embedded specimens of Trichuris suis. Microscopic lesions were characterized by crypt and gland hyperplasia with branching and depletion of goblet cells in the ileum and cecum. Multiple areas of superficial necrosis and ul­ceration were recognized with numerous protozoans morpho­logically resembling Balantidium coli trophozoites adhered to the necrotic surface of the cecum. Lawsonia intracellularis was identified intralesionally by Warthin-Starry stain and immuno­histochemistry. Lawsonia intracellularis should be considered a differential etiologic diagnosis for diarrhea and enteropathy in swine in Uruguay.

Canine rangeliosis is a disease caused by the protozoan Range­lia vitalii and transmitted by ticks. It affects domestic and wild canines, causing hemolytic anemia and thrombocytopenia. In Uruguay it has been reported in the following counties: Arti­gas, Salto and Treinta y Tres. The present study describes a ca­nine rangeliosis outbreak in the northwest littoral of Uruguay, diagnosed by epidemiological, clinical, hematological, anato­mopathological and molecular techniques (PCR / sequencing). The study was based on 9 cases of dogs, Fawn Brittany Grif­fon breed, used for hunting; from a farm near Quebracho, Pa­ysandú County. Eight animals died and one responded to the treatment. The main clinical signs were apathy, jaundice, fever, bloody diarrhea and bleeding from nostrils and tips of the ears. The hematological findings were anemia, thrombocytopenia and leukocytosis. Main macroscopic lesions were characterized by paleness, generalized jaundice, splenomegaly, lymphadenomeg­aly, and hepatomegaly. The principal histopathological lesions were interstitial nephritis with tubular degeneration and necro­sis, myocarditis, centrolobulillar hepatic necrosis, edematous and congestive lung, lymphoadenitis and perivascular mononu­clear inflammatory infiltration in spleen. In several organs were observed R. vitalii zoites inside the cytoplasm of endothelial cells. In some animals and as well as in dog kennels were pres­ent Amblyomma aureolatum. DNA was extracted from blood of two cases and a fragment of the 18s ribosomal RNA gene of Piroplasm was amplified by PCR. The sequence obtained was compared to the sequences registered in the GenBank using the BLAST tool. The result showed a homology between 99-100% with R. vitalii.

The equine influenza virus subtype H3N8 has been considered the most important respiratory pathogen of horses, due to its highly contagious nature and its rapid spread among susceptible animals. It has been shown that the degree of protection deter­mined by inactivated vaccines, is closely related to the level of circulating antibodies against the virus hemagglutinin Equine influenza. The aim of this study is to determine the susceptibil­ity of sport horses in Uruguay to infection by equine influenza virus by measuring antibodies SRH (single radial hemolysis), and study its association with factors such as age, horse breed, sex, and vaccination history. 1532 equine sera of different horse breed, sex and vaccination status by SRH were processed, and giving missing values only 1390 was considered for the statis­tical analysis. To observe the behavior of the observed frequen­cies of the SRH univariate analysis was performed Low cover­age of vaccination against Equine Influenza in sport horses was observed (23%) and a very low level of virological and clini­cal immunity (27% and 35% respectively) against infection of H3N8 virus test determined by SRH test. Increased susceptibil­ity to infection by the H3N8 virus was observed in horses with­out updated vaccination, Arab and Quarter mile breed horses, horses younger than 2 years old, and in castrated males horses.

Many techniques have been developed for the estimation of dry matter intake (DMI) by animals under grazing conditions. How­ever, the selective intake of pasture grass by cattle incorporates an important source of variability that affects the confidence of the obtained results. The technique based on the external marker titanium dioxide (TiO2) has reported to be a reliable alterna­tive in estimating animal intake. The objective of this study is to compare the TiO2 technique under grazing conditions with respect to three animal intake prediction equations, which were developed under similar conditions of our experiment. The data analyzed correspond to a crossover experiment using 20 Here­ford heifers, grouped into two lots of 10 according to their live weight (LW), and carried out during two periods: winter and spring 2013. In both periods, each lot was assigned to two pas­tures with contrasting initial quality: 65.5% vs. 71.2% dry mat­ter digestibility (DMD); 54.9% vs. 40.9% neutral detergent fiber (NDF), and 11.6% vs. 22.8% crude protein (CP). Each experi­mental period consisted of 8 days of adaptation to the diet plus 5 days of measurements. From the beginning, 10 g of TiO2 per animal were daily supplied. During each measurement period, a fecal composite sample per animal was elaborated from its daily collection per rectum, and its chemical composition was determined. The results of DMI (kg d-1) measured for both pas­tures using the TiO2 technique showed greater variability than the results predicted by any of the three equations.