Jorge Campos

Use of chitin to improve a Beauveria bassiana alginate-pellet formulation

Abstract A study was undertaken to evaluate optimum concentrations of chitin in sodium alginate pellet formulations to enhance conidia production. Chitin concentrations tested were 0, 0.5, 1, 2, 3 and 4% (w/v), with (2%, w/v) or without wheat bran. The different chitin-wheat bran pellet combinations were prepared with Beauveria bassiana isolate Qu-B306 at 108 conidia mL–1. After 21 days of incubation in a humid chamber at 28°C, conidia production was assessed. Improvements up to three times the initial conidia number were achieved using 2% chitin and 2% wheat bran. Higher levels of chitin decreased the number of conidia per pellet. For all chitin concentrations, conidia number increased with the addition of wheat bran (P≤0.05). Contamination by saprophytic fungi was reduced by the incorporation of chitin in the pellet formulation.

Síndrome de cava superior secundario a mesotelioma fibroso pleural

Los mesoteliomas fibrosos o mesoteliomas pleurales benignos son tumores poco frecuentes que en realidad parecen ser de estirpe mesenquimal (fibromas subpleurales). Por lo general, suelen descubrirse de manera casual y su pronostico es favorable tras la cirugia. Si son de gran tamano pueden originar manifestaciones extrapulmonares (osteoartropatia hipertrofica, hipoglucemia, etc.). Se presenta un caso de mesotelioma fibroso pleural de excepcional tamano que se inicio clinicamente como un sindrome de cava superior, complicacion que no ha sido descrita en la literatura.

VARIABILIDAD ASOCIADA A LA DETERMINACIÓN DE RESIDUOS DE CLORPIRIFOS AL SER APLICADO EN UN HUERTO DE MANZANOS

El presente estudio tiene por objetivo probar mediante ensayos supervisados la variabilidad de los residuos de clorpirifos (CHP) asociados a una metodologia de muestreo validada en terreno, al aplicar el ingrediente activo (IA) en huerto de manzanos, con dos diferentes metodologias de aspersion y en epocas diferentes de desarrollo vegetativo. Se estudio la persistencia al aplicar 1,8 kg ha -1(Lorsban 50%WP®, Dow AgroScience, USA), mediante nebulizadora con bomba de espalda con motor (NBEM) y con nebulizadora de alto volumen (NAV). Se evaluo el modelo que representa el mejor ajuste de la declinacion de los residuos a traves de regresion no lineal. Los resultados muestran altos coeficientes de variacion (CV) en ambos metodos de aplicacion, NBEM (69%) y NAV (43%). La variabilidad del muestreo de manzanas contribuye con un 99.3% con NBEM y 97.7% con NAV. Los resultados muestran una disminucion inicial rapida del CHP, con una vida media para manzanas, hojas y suelo de 5,0; 2,3 y 4,5 dias para NBEM y de 8,3; 2,7 y 11,2 dias para NAV, respectivamente. El modelo de declinacion ajustado para cada sustrato no permite modelar la degradacion de los residuos de CHP a traves de un modelo simple.

¿Es Alstroemeria pulchra Sims var. maxima Phil. (Alstroemeriaceae) un miembro del complejo A. magnifica Herbert?: Estudio colorimétrico de los tépalos externos e internos de la flor

Alstroemeria pulchra var. maxima es un taxon endemico de Chile descrito por R.A. Philippi en 1864, cuya posicion sistematica es controversial; aunque Bayer en 1987 transfiere este taxon a A. magnifica con el rango de subespecie, Munoz & Moreira en 2003 retoman el concepto original de Philippi. Con el objetivo de proporcionar nuevos caracteres para decidir si A. pulchra var. maxima es un miembro del complejo A. magnifica o debe permanecer como una variedad de A. pulchra como fue originalmente descrita, se analizo el color de los tepalos externos, internos superiores e interno inferior, utilizando un espectrofotometro colorimetro Hunterlab Colorquest. Se trabajo con flores de ocho poblaciones de Alstroemeria L. pertenecientes a estas dos especies endemicas de Chile: cinco poblaciones de A. magnifica Herbert y tres poblaciones de A. pulchra Sims. Las mediciones en el espacio CIELab permiten distinguir A. magnifica de A. pulchra sobre la base del color de los tepalos externos y del tepalo interno inferior, pero no por el color de los tepalos internos superiores. Se concluye que el color de la flor es un nuevo caracter que confirma que la var. maxima pertenece a A. pulchra y no al complejo A. magnifica.

Caracterización del Crecimiento en el Primer Año de Cultivares de Espárrago (Asparagus officinalis L.) en Maceta

Para evaluar el crecimiento de cuatro cultivares de esparrago (Asparagus officinalis L.) durante el primer ano desde siembra se establecio un ensayo en la Provincia de Nuble (36°34? lat. Sur, 72°06? long. Oeste, 144 m.s.n.m). Los cultivares evaluados fueron: Atlas, UC157F1, JWC1 y UC157F2. Se observo una alta correlacion positiva entre la acumulacion de biomasa y el tiempo (dias desde siembra) y tambien con la temperatura. El modelo lineal biomasa vs. tiempo obtuvo una alta correlacion (r = 0,96), por lo que no seria necesario contar con datos climaticos para estimar el crecimiento del esparrago en esta etapa. La inclusion de la radiacion fotosinteticamente activa al modelo termal lineal no contribuyo a mejorarlo. Los modelos lineales y por ende las tasas de crecimiento relativo de follaje y corona, que corresponden a la pendiente de la recta, solo se diferenciaron entre los cv. Atlas y UC157F2. Sin embargo, esto no se tradujo en diferencias para la mayoria de los parametros vegetativos evaluados. El cv. UC157F1 solo se diferencio en el peso seco de follaje de JWC1 y en el numero de brotes de Atlas. A nivel radicular no hubo diferencias entre cultivares, excepto en los solidos solubles (UC157F1 menor que JWC1). Los nuevos cultivares Atlas y JWC1 mostraron una calidad final de corona similar a los hibridos tradicionales UC157, expresada como peso fresco, numero de yemas y de raices.

Soil profile distribution of total C content and natural abundance of 13C in two volcanic soils subjected to crop residue burning versus crop residue retention

Abstract Soil organic carbon (SOC) plays a key role in crop productivity and soil quality. Conservation agriculture has a positive effect on SOC accumulation in the surface soil horizons, but little information is available regarding the effect of the removal of crop residues by burning. This study aimed to assess the impact of different types of crop residue management practices on the total C distribution and natural abundance of 13C (‰, δ13C). Two volcanic soils, located in the Mediterranean temperate zone of Southern Chile, were studied: an Ultisol (Collipulli Series, CPL) and an Andisol (Santa Bárbara Series, SBA). Both soils had been cultivated under direct-drilling and a typical annual crop rotation system for a long period of time. Two different types of crop residue management practices were imposed in both soils: (i) crop residue burning (CPL-B; SBA-B) and (ii) crop residue retention over the soil (CPL-R; SBA-R), corresponding to treatments B and R, respectively. Soil profile distribution of the C content and natural abundance of 13C were analysed for bulk soils (down to 100 cm depth) and three particle-size fractions of the soils (down to 20 cm of soil depth): (a) ≤ 53 µm, (b) 53-212 µm and (c) ≥ 212 µm. It was found that the effect of crop residue management can be observed in the variations of C content and δ13C in the soil profile in both volcanic soils. Crop residue burning (B treatment) increased the C content in bulk soil and the particle-size fractions. On the other hand, soil organic matter of crop residue retention (R treatment) showed higher natural abundance of 13C (δ13C) compared with residue burning (B treatment) in the two volcanic soils. R treatment enriched the particle-size fractions (except ≥ 212 µm fraction of CPL soil) with 13C. Factors that could account for these findings are also discussed here.

CAN DIETARY DRIED OREGANO IMPROVE THE DIGESTIBLE NUTRIENT INTAKE OF GROWING GOATS

The aim of this study was to evaluate the effect of dietary dried oregano on the intake of dry matter and digestible nutrients in growing goats. Fifteen 7-month old male goats were fed on diets with 0, 10 and 50 g kg-1 of dried oregano based on dry matter (DM). A completely randomized design was used, and each animal was assigned to one pen and treatment (3 treatments x 5 replicates) for 45 days. Voluntary intake of DM and nutrient digestibility were measured using acid insoluble ash as an indigestible marker. Daily weight gains were 146, 126 and 122 g d-1 per treatment (P = 0.08). A positive effect on digestible nutrient intake was obtained with both oregano concentrations. Linear and quadratic effects were obtained in the digestible neutral detergent fibre (NDF) and the other nutrient intakes, respectively. No effect was observed in DM or digestible acid detergent fibre (ADF) intakes. Therefore, there was a positive effect on the coefficient of DM in both treatments and NDF digestibility in the treatment with the highest concentration of dietary dried oregano. The positive effect of dried oregano on the goats’ diet in terms of digestible nutrient intake suggests that oregano essential oil (EO) modifies the ruminal microflora by improving digestibility, rather than having an effect on the feeding behavior of the animal due to the flavour of the diet. The treatment containing 10 g kg-1 of dietary dried oregano promoted voluntary DM consumption and increased the intake of digestible nutrients, while that containing 50 g kg-1 of dried oregano only promoted the intake of digestible NDF.

Lentil (Lens culinaris L.) growth promoting rhizobacteria and their effect on nodulation in coinoculation with rhizobia

ABSTRACT Lentil is cultivated in Chilean Mediterranean drylands, in areas with soils that are nutrient depleted and eroded. Inoculation of lentil with rhizobia in co-inoculation with growth promoting rhizobacteria would allow higher biomass and an opportunity for early nodulation and increased nitrogen fixation. The objective of this research was to select rhizosferic bacteria (PGPR) from lentils and to evaluate their effect on lentil nodulation in co-inoculation with rhizobia. Sixty three lentil rhizobacteria isolates where obtained from nine soils in the mediterranean area. These were fingerprinted through BOX-PCR reducing the number to 57 distinct strains. The strains were evaluated for ACCdeaminase activity, IAA production and compatibility with rhizobia. Seventeen strains showed ACC-deaminase activity, all of them synthesized IAA and 38 were compatible with the rhizobia. Ten selected strains were identified as Pseudomonas spp. through 16S rRNA sequencing. The strains were inoculated in lentil seedlings growing on seed germination pouches, to evaluate nodule formation. The strain LY50a increased early nodulation in 85% in comparison to the control inoculated with rhizobia (AG-84) only. In conclusion, bacteria from the rhizosphere from Mediterranean soils of Chile can be used as nodulation promoters in lentils.