UTILIZACIÓN DE ESTIMADORES PARA DETERMINACIÓN DE BIOMASAA CAMPO

Direct or destructive methods determine the values of existing biomass area in the field exactly. However, usually some operating and evaluation of a natural resource can be a source of disturbance to the natural system. From the contribution of new technologies, they tried to replace these methods by other direct or indirect non-destructive, where the powers of observation and estimation of biomass researchers with values obtained by cutting biomass combined. Among these methods we can name: use the double sampling rates (BEI) and estimation of direct weight field (BEP). The aim of this study was to compare the use of such estimators with sampling point scale to assess the availability of dry matter in a community located at the beginning of the origin Chucul stream. Data collection was conducted over three years (2012-2013-2014). Bimonthly, ten samples, with quadrants of 0.25 m2, spaced 30 m was cut and the biomass was weighed. 50 visual observations uncut assigning categories 1 to 5 and values estimated by the amount of forage available. Then, through linear regression, the relationship between the BEI and visually estimated BEP and cutted and weighed. The total aboveground biomass of pasture ranged from 153.52 and 386.78 g / m2. The regression estimates for different sampling dates ranged between 0.47 and 0.92 to 0.02 and 0.96 BEI and for BEP. To perform the analysis of variance estimates obtained was observed that there are significant differences between the BEI and BEP results, indicating a greater degree of adjustment for BEI to BEP. Showing that both serve as estimates of primary production in the study site

Effects of post-emergent herbicides on Trichoderma harzianum, a potential biocontrol agent against Sclerotinia sclerotiorum in soybean cropping

Trichoderma harzianum is a potential biocontrol agent against Sclerotinia sclerotiorum in soybean. Information is needed on the compatibility of this biocontrol agent and the post-emergent herbicides used in soybean cropping. Haloxyfop R Methyl (EC 10.4%), Glyphosate (SL 48%), Imazamox (WG 70%) and Imazethapyr (SL 10%) were evaluated for their effects on the mycelial growth of T. harzianum on in vitro agar plates. Glyphosate (2000 ppm), Imazethapyr (500 and 250 ppm) and Haloxyfop R Methyl (1000, 500 and 100 ppm) reduced the mycelial growth of T. harzianum. Imazamox had no effect at any concentration. Subsequently, all the herbicides were assessed for their effect on soil populations of T. harzianum. Greenhouse assays conducted with non-sterile soil inoculated with T. harzianum and a specific herbicide were sampled before pesticide application and after 30 days. The number of colony forming units per gram of soil (c.f.u./g of soil) was evaluated with a soil dilution technique using Trichoderma selective medium (TSM). No detrimental effect was revealed.Facultad de Ciencias Agrarias y Forestale

Evaluación De Métodos Indirectos Para Estimar Biomasa En Un Pastizal Natural Del Sur De Córdoba (Argentina Central)

To optimize grassland management, it is important to evaluate seasonal changes in quality and production according to the characteristics of the environment, allowing planning and rational use of resources. With the objective of finding estimators that fit the actual production of aerial biomass in natural pastures, it was proposed to estimate biomass with the average height of the pasture and by double sampling, by determination by direct weight estimation and by estimation with index assignment. For this purpose, a natural grassland located in the area of influence of the final section of the Chucul River Basin (La Felipa Natural Reserve) was surveyed. Periodically from April 2013 to March 2016, in ten samples taken with 0.25 m2 quadrants, the biomass was cut and weighed, and the height of the present species was measured. In the area surrounding each quadrant, 50 uncorrected visual observations were made by assigning indexes from 1 to 5 and values of estimated weight according to the amount of forage available. Then a correlation analysis was performed and linear regressions were determined between the parameters studied. Real biomass (BR) showed a significant correlation with biomass estimated by Weight (BEP) and biomass estimated by Index (BEI) (p≤0.05)

Effects of post-emergent herbicides on Trichoderma harzianum, a potential biocontrol agent against Sclerotinia sclerotiorum in soybean cropping

Trichoderma harzianum is a potential biocontrol agent against Sclerotinia sclerotiorum in soybean. Information is needed on the compatibility of this biocontrol agent and the post-emergent herbicides used in soybean cropping. Haloxyfop R Methyl (EC 10.4%), Glyphosate (SL 48%), Imazamox (WG 70%) and Imazethapyr (SL 10%) were evaluated for their effects on the mycelial growth of T. harzianum on in vitro agar plates. Glyphosate (2000 ppm), Imazethapyr (500 and 250 ppm) and Haloxyfop R Methyl (1000, 500 and 100 ppm) reduced the mycelial growth of T. harzianum. Imazamox had no effect at any concentration. Subsequently, all the herbicides were assessed for their effect on soil populations of T. harzianum. Greenhouse assays conducted with non-sterile soil inoculated with T. harzianum and a specific herbicide were sampled before pesticide application and after 30 days. The number of colony forming units per gram of soil (c.f.u./g of soil) was evaluated with a soil dilution technique using Trichoderma selective medium (TSM). No detrimental effect was revealed.Facultad de Ciencias Agrarias y Forestale

Determinación de la correlación entre datos de biomasa obtenidos a campo y ndvi obtenidos por sensores remotos a lo largo del arroyo Chucul (Pcia. Córdoba)

The values of green biomass (Bv) measured in a grassland were associated with index values of normalized difference vegetation index (NDVI) from satellite data in three relict natural grassland on stream Chucul, from his beginning site 1 (32° 49'21, 0” S and 64° 24`07.0”W) until its demise in plain area: site 3 (33° 06` 25.5`` S and 63° 32`49.1`` W). Under the hypothesis of correspondence of Bv and data obtained by images, the aim of this work is to determine the relationship between measured field data and satellite data in natural grasslands. Seasonally during the 2009-2011 cycle were sampled at random with 10 replicates of 0.25 m2 recording floristic list. To determine Bv in each plot the biomass was cut and separated in green and dry compartments and dryed to constant weight. For digital analysis bands 3 and 4 of Landsat 5 TM image (Path 228 Row 083) were used foreach site close to the sampling date. The highest values of green biomass were determined for site 3, in December 2011: 189.6 g/m2 and in March for sites 1 and 2: 105.74 and 115.22 g/m2. Among all the observed values of biomass and NDVI estimated the correlation coefficient was highest at site 3 (R= 0.50). The results of the work for site 3 validate the hypothesis and indicats of the aptitude of digital images for study the status and changes in vegetation.Los valores de biomasa aérea verde (Bv) medidos en el pastizal se relacionaron con los valores de índices de vegetación de diferencia normalizada (NDVI) provenientes de datos satelitales en tres relictos de pastizales naturales en las riveras del arroyo Chucul, desde su nacimiento: sitio 1 (32° 49´21,0``S y 64° 24` 07,0`` W), hasta su desaparición en zona de llanura: sitio 3 (33° 06`25,5``S y 63° 32`49,1``W). Bajo la hipótesis de correspondencia de Bv y datos obtenidos por imágenes, se planteó como objetivo de este trabajo determinar la relación entre datos medidos a campo y datos satelitales en pastizales naturales. Estacionalmente durante el ciclo 2009-2011 se realizó un muestreo al azar con 10 réplicas de 0,25 m2 registrando lista florística. Para determinar Bv se cortó biomasa en cada parcela separando en compartimentos verde y seco y se llevó a estufa hasta peso constante. Para el análisis digital se utilizaron las bandas 3 y 4 de una imagen Landsat 5 TM (Path 228 Row 083), por cada sitio próxima a la fecha de muestreo. Los mayores valores de Biomasa verde se determinaron para el sitio 3, en diciembre de 2011: 189,6 g/m2 y en marzo para los sitios 1 y 2: 105,74 y 115,22 g/m2. Entre todos los valores observados de biomasa y estimados por el NDVI el coeficiente de correlación más alto correspondió al sitio 3 (R=0.50). Los resultados del trabajo para el sitio 3 corroboran en parte la hipótesis planteada, indicando escasamente, en este caso, la aptitud de las imágenes digitales para realizar estudios de seguimiento del estado y de cambios en la vegetación

Relación Entre Biomasa Aérea Y Producción Primaria Neta Con Las Variaciones Estacionales De Precipitaciones Y Temperaturas En Pastizales Del Sur De La Provincia De Córdoba

Natural grasslands of the planet are very important reservoirs of flora and fauna that provide various ecosystem services benefits. To maintain and improve their condition, it is necessary to study them and understand their composition and functioning as well as their evolution over time. In the present work the influence of climatic variables, temperature and rainfall on the aerial biomass behavior and the net primary productivity of a pasture were analyzed. For this purpose, a natural pasture was located on the banks of the Chocancharava River, in the town of Río Cuarto. Monthly sampling (September 2014 - August 2015) was carried out, cutting aerial biomass at ground level with tusar scissors and collecting biomass and mulch in 10 quadrants of 0.5 x 0.5 m (0.25 m2) and dried in stove to constant weight. This material was separated into compartments: green (BV), dry (BS) and mulch (BM) to determined the available biomass. For statistical analysis, a completely randomized design (DCA) of fixed effects with Infostat program was used. The highest contribution of BV was in summer months, 4262 kg / ha of 8772 kg / ha corresponding to the total cycle. The highest BS was determined in winter with 2715 kg / ha of the total 6663 kg / ha. The litter presented a behavior similar to the BV, with the highest peaks in summer months 2478 kg / ha of 6004 kg / ha. The PPN presented a marked spring increase. Adding the positive increases in monthly PPN, a value of 1206.6 kg / ha * year was determined. Considering that higher temperatures and rainfall are recorded in summer (average 22 ° C and 422 mm), it could be assert that these variables would explain a significant part of the variability in the total aerial biomass production of the pasture

Effects of post-emergent herbicides on Trichoderma harzianum, a potential biocontrol agent against Sclerotinia sclerotiorum in soybean cropping

Trichoderma harzianum is a potential biocontrol agent against Sclerotinia sclerotiorum in soybean. Information is needed on the compatibility of this biocontrol agent and the post-emergent herbicides used in soybean cropping. Haloxyfop R Methyl (EC 10.4%), Glyphosate (SL 48%), Imazamox (WG 70%) and Imazethapyr (SL 10%) were evaluated for their effects on the mycelial growth of T. harzianum on in vitro agar plates. Glyphosate (2000 ppm), Imazethapyr (500 and 250 ppm) and Haloxyfop R Methyl (1000, 500 and 100 ppm) reduced the mycelial growth of T. harzianum. Imazamox had no effect at any concentration. Subsequently, all the herbicides were assessed for their effect on soil populations of T. harzianum. Greenhouse assays conducted with non-sterile soil inoculated with T. harzianum and a specific herbicide were sampled before pesticide application and after 30 days. The number of colony forming units per gram of soil (c.f.u./g of soil) was evaluated with a soil dilution technique using Trichoderma selective medium (TSM). No detrimental effect was revealed.Facultad de Ciencias Agrarias y Forestale

Mecanismos de accion de Trichoderma spp. para el biocontrol de la septoriosis del trigo

El objetivo de esta investigación fue conocer los posibles mecanismos biológico desencadenados por Trichoderma spp como biocontrolador de la Septoriosis del trigo. El aislamiento de las especies de Trichoderma spp se realizó a partir de suelos cultivados con trigo de La Plata. Se obtuvieron y caracterizaron 30 cepas. Para los bioensayos en invernáculo, se realizaron los siguientes tratamientos: plantas control; plantas inoculadas con S. trítici; semillas de trigo “pelleteadas” con Trichoderma spp y semillas de trigo “pelleteadas” con Trichoderma spp y posteriormente inoculadas con S. trítici. A los 21 días de la inoculación, en la primera hoja de cada planta se registró el porcentaje de necrosis y de picnidios desarrollado. De aquellas cepas que demostraron mejor efecto biocontrolador se realizaron pruebas de la actividad antifúngicas del fluido proteolítico intercelular y el peso seco de las raíces y de la parte aérea. Los resultados obtenidos indican que las cepas 2, 4, 5 y 8 produjeron tanto una reducción del área necrosada como una disminución de la superficie cubierta con picnidios. Por lo tanto se las señala como cepas con un potencial biocontrolador frente a la enfermedad. A estas cepas se les investigó el mecanismo de acción. Las cepas 8 y 2 demostraron una elevada actividad proteolítica lo que indicaría que estarían relacionadas con un aumento en la resistencia sistémica inducida en la planta. La cepa 5 aumentó el peso seco aéreo y la 4 el peso seco de la raíz, produciendo plantas más robustas y como consecuencia la reducción de la enfermedad.In the present work, experiments were carried out to determine the possible mechanisms of action of isolates of Trichoderma spp as a biocontrol agent of leaf blotch of wheat. The Trichoderma spp. isolates were coming from soil cultivated with wheat in La Plata area. Thirty isolates were characterized. For the greenhouse bioassay the following treatments were done: control plants, plants inoculated with S. trítici, wheat seeds pelleted with Trichoderma spp. and wheat seed pelleted with Trichoderma spp and inoculated with S. trítici. After 21 days of inoculation, in the first leaf the necrotic area and pycnidial coverage were evaluated. The leaf apoplast antifungal proteolytic activity and dry weight of aerial parts and roots was measured in plants treated with the strains that demonstrated the best behaviour as biocontrol agents. The results showed that the strains 2, 4, 5 y 8 decreased significantly tne necrotic area en the pycnidial coverage. Thus, this strains have biocontrol activity against the disease. The mechanism of action of those strains were investigated. Plants grown from seed coated with 8 and 2 isolates of Trichoderma spp. demostrated an increased antifungal proteolytic activity, it could be related with sistemic induced resistance in plants. On the other hand, The strains 4 and 5 they produced an increase of dry weight of roots and aerial parts respectively producing plant more robust and as a consequence the disease reduction

Control quimico-biológico de la mancha de la hoja del trigo en el campo

Se evaluó el efecto biocontrolador de dos cepas de Trichoderma harzianum solas y en combinación con fungicidas, sobre la severidad de la mancha de la hoja del trigo, con diferentes técnicas de aplicación en tres estadios fenológicos (plántula, macollaje, espigazón). Plantas de la variedad Buck 55CL2 se sometieron a diferentes tratamientos: testigo inoculado con el patógeno, plantas provenientes de semillas peleteadas con las cepas de T. harzianum e inoculadas, plantas provenientes de semilla peleteada y pulverizadas en hoja con T. harzianum más inoculación o con aplicación combinada de solución de T. harzianum y fungicida aéreo 7 días antes de la inoculación con el patógeno. Se evaluó el control de la enfermedad a través de la disminución de la severidad. En los estados GS 12 (plántula) y GS 31 (macollaje), sólo se evaluó desarrollo de tejido necrosado por la baja incidencia de picnidios. En GS 54 (espigazón), sólo se evaluó porcentaje de cobertura picnidial por valores de necrosis muy altos en todos los tratamientos. Con sólo el peleteado de la semilla se alcanzó protección hasta el último estadio (p≥0.05). Valores más bajos de severidad se obtuvieron cuando las semillas fueron peleteadas y la plántula recibió además, media dosis de fungicida Amistar-xtra (p≥0.05). Para proteger el medio ambiente, se recomienda el uso de la cepa Th5cc que con 3 aplicaciónes (peleteado en semilla y dos aplicaciones aéreas en GS 31 y GS 54) disminuye la severidad hasta espigazón (p≥0.05)

Trichoderma harzianum: inductor de la RSI frente a la mancha de la hoja del trigo

La mancha de la hoja de trigo, causada por Mycosphaerella graminicola (Fuckel) Shroeter, in Cohn (anamordo S. tritici Rob.et. Desm.) es una importante enfermedad en muchas areas productoras de trigo del mundo. Los componentes químicos han sido tradicionalmente utilizados para el control de las enfermedades fúngicas de los cultivos, sin embargo el abuso de su empleo ha favorecido el desarrollo de patógenos resistentes a los fungicidas. Con el objetivo de minimizar el uso de estos productos, el control biológico se considera una opción atractiva. En este sentido, los aislamientos de Trichoderma pueden ejercer el biocontrol de hongos fitopatogenos indirectamente, compitiendo por el espacio y por nutrientes, modificando las condiciones ambientales, estimulando el crecimientos de las planas y sus mecanismos de defensa