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Search Results: 1 - 10 of 233 matches for " Samaniego Gaxiola "
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Germinación y sobrevivencia de esclerocios de (Phymatotrichopsis omnivora) en respuesta a NaOCl y suelo con glucosa
Samaniego Gaxiola, José Alfredo;
Agricultura técnica en México , 2008,
Abstract: sclerotia of phymatotrichopsis omnivora can survive for 20 years in the soil; however, if sclerotia are exposed to chemical agents or microbial competition in soil, survival is reduced to few weeks. the objective of this research was to study the germination and survival of p. omnivore sclerotia, treated first with a solution of naocl and then exposed to microbiota competition in soil supplemented with dextrose. the experiments were carried out at 'la laguna' research station of the national research institute for forestry, agriculture and livestock under a completely random factorial design. sclerotia were immersed in 200, 500 and 3 000 ppm naocl solutions during 0.3, 1, 8, and 72 h. at two temperatures, 15-20 and 28 °c, afterwards were placed in soil added with 0.0, 0.125, 0.25 and 0.5 mg g-1 of dextrose during 14 days under saturated conditions at 28 °c. sclerotia immersed into a 3 000 ppm solution of naocl during 20 min showed 90% germination in sterile sand and pda and only 15% in non-sterile sand and pda. when sclerotia were germinated before being immersed in naocl, viability was 100% in all substrates utilized. survival of sclerotia decreased with the increase in the time of immersion, concentration of naocl, and concentration of dextrose added to the soil. sclerotia immersed during one hour or more in 1 000 ppm or higher of naocl solution and placed in soil with 0.25 or 0.5 mg g-1 of added dextrose showed a maximum survival of 20%. sclerotia survival was high in some treatments at 15-20 °c than in similar treatments at 28 °c, possible due to a protective effect of naocl on sclerotia exposed to soil microbiota enhanced by added dextrose.
Research Perpectives on Phymatotrichopsis omnivora and the disease it causes*
Samaniego-Gaxiola, José Alfredo;
Agricultura técnica en México , 2007,
Abstract: phymatotrichopsis omnivora continues to be an important plant pathogen. the diseases caused by this fungus result in economic losses reaching millions dollars in northern mexico and southern united states of america. however, limited research has been done about this pathogen in recent years. p. omnivora is a soil-borne fungus with a host range of more than 2000 plant species, and can survive in soil for more than 10 years. research on this fungus and the diseases it causes would help to reduce the negative impact on crop productivity and to improve the management of other diseases caused by fungi. in this work, the results of some research of p. omnivora are discussed, and future lines of research are proposed.
Efecto del pH en la Sobrevivencia de Esclerocios de Phymatotrichopsis omnívora (Dugg.) Hennebert Expuestos a Tilt y Trichoderma sp.
Samaniego-Gaxiola, José Alfredo;
Revista mexicana de fitopatología , 2008,
Abstract: previous to determination of the ph effect in just buffer solutions or ammended with naocl on sclerotia of phymatotrichopsis omnivora, in this work, sclerotia survival exposed during 14 days to an isolate of trichoderma sp. in buffers solutions at ph 4, 5, 6, 8.2, and 10.4, and acetic acid solutions at 0, 25, 50, and 100 ppm was evaluated. sclerotia survival was also evaluated in aqueous and buffer solutions ammended with 1000 ppm of tilt (propiconazole) during one minute up to three day exposure. sclerotia survival in presence of trichoderma sp. after 14 days was 90 and 10% at ph 6 and 8.2, respectively, but at ph 4, 5, and 10.4 sclerotia did not survive a single day. in the presence of trichoderma sp. incubated 14 days at 0, 25, 50, and 100 ppm of acetic acid, sclerotia showed 100, 80, 40, and 0% survival, respectively. the time needed to kill 100% sclerotia diminished 864 and 216 times using 1000 ppm of tilt at ph 4 and 5, respectively, with respect to the time needed to obtain the same effect at ph 7 (3 days). the ph had a determinant effect on survival of sclerotia of p. omnivora.
Efecto del pH en la Sobrevivencia de Esclerocios de Phymatotrichopsis omnívora (Dugg.) Hennebert Expuestos a Soluciones Amortiguadoras, ácido Acético y NaOCl
Samaniego-Gaxiola, José Alfredo;
Revista mexicana de fitopatología , 2008,
Abstract: phymatotrichopsis omnivorous is a limiting factor for the exploitation of several agricultural crops in mexico and the united states, and there are not practical control methods. since the fungus does not cause evident damage to plants in acid soils, a study was undertaken on the effect of ph on sclerotia survival in: buffers solutions (ph 4, 5, 6, 7 and 7.8); buffers solutions ammended with 100, 500, 1000, and 3000 ppm of naocl; solutions at 0, 25, 50, and 100 ppm of acetic acid; and in flooded or without flooded soil ammended with acetic acid at 0, 2500, 5000, 10000, 25000, and 50000 ppm. sclerotia were incubated in the solutions or soils from one day up to three weeks at 28°c, with the exception in naocl solutions, where incubation lasted four hours. sclerotia did not survive after one week in buffer solutions at ph 4 and 5, while at ph 6, 7, and 7.8 they survived 100, 80, and 1% after three weeks, respectively. sclerotia were 100% viable in the solutions or soils ammended with acetic acid. a 20% of sclerotia survived in naocl solution at 1000 ppm and ph 6.
Diversidad de géneros de hongos del suelo en tres campos con diferente condición agrícola en La Laguna, México
Samaniego-Gaxiola, José Alfredo;Chew-Madinaveitia, Yasmín;
Revista mexicana de biodiversidad , 2007,
Abstract: this study was carried out in agricultural soils in la laguna, coahuila - durango, mexico (annual precipitation 80-250 mm). the structure of soil fungal genera of three field soil was studied. in soil of tierra blanca, an orchard pecan of 51 years, there were isolated 23 genera of soil fungi, and only 12 genera of other two field soils (el chupón, a pecan orchard of 14 years, and san jorge, culturing with alfalfa). for each genus of soil fungi there were calculated the importance value index (i v i). the genus fusarium showed the greater i v i of the three field soils (71-98). the diversity (shannon's index) of genera of fungi was different from each soil according to confidence intervals (95%), with values of 1.89, 1.72 y 1.19 for tierra blanca, el chupón and san jorge, respectively. additional ecological indexes were calculated, as simpson, maxim richness (h' max), regularity (j'). the values of index simpson and j' were similar between tierra blanca and san jorge, but only h' max was similar between el chupón and san jorge. the similarity index of sh?resen was equal for tierra blanca vs. el chupón, or tierra blanca vs. san jorge (51.4), whereas el chupón vs. san jorge was 58.3. the index β for the genera of fungi in tierra blanca vs. el chupón or tierra blanca vs. san jorge was 0.48, but san jorge vs. el chupón was 0.83. the genera of soil fungi found in la laguna are 67-75% similar to soil fungi isolated from desert, such as the israel desert, but in soils of la laguna the structure of genera fungal is different; here fusarium is the most abundant, and appear new genera such as trichoderma. the changes of soil mycobiota could be the result of the effect of agricultural activity during the last 50 years.
Diversidad de géneros de hongos del suelo en tres campos con diferente condición agrícola en La Laguna, México Diversity of soil fungi genera in three different condition agricultural fields in La Laguna, Mexico
José Alfredo Samaniego-Gaxiola,Yasmín Chew-Madinaveitia
Revista mexicana de biodiversidad , 2007,
Abstract: En La Laguna, Coahuila-Durango, México (zona con una precipitación anual entre 80 a 250 mm) se estudió la estructura de géneros de hongos del suelo en 3 campos de cultivo agrícola. Del suelo de Tierra Blanca, una huerta de nogal de 51 a os, fueron aislados 23 géneros de hongos y de otros 2 suelos, una huerta de nogal de 14 a os, nombrada El Chupón y un campo con cultivo de alfalfa, denominado San Jorge, se aislaron l2 géneros. Para cada género se calculó su valor índice de ímportancia (V I I). El género Fusarium tuvo el mayor V I I en los 3 suelos estudiados (71-98). La diversidad (calculada con el índice de Shannon) de géneros fue diferente para cada suelo de acuerdo con intervalos de confianza (95%), con valores de 1.89, 1.72 y 1.19 para Tierra Blanca, El Chupón y San Jorge, respectivamente. Se calcularon índices ecológicos adicionales, como, Simpson, máxima riqueza (H' max) y regularidad (J'). Los valores del índice de Simpson y de J' fueron similares en Tierra Blanca y San Jorge, pero sólo H' max fue similar entre El Chupón y San Jorge. El índice de similitud de Sh resen fue igual al comparar Tierra Blanca con El Chupón o Tierra Blanca con San Jorge (51.4), pero distinto entre el Chupón y San Jorge (58.3). El índice β para las combinaciones Tierra Blanca vs. San Jorge y Tierra Blanca vs. El Chupón fueron de 0.43, pero para San Jorge vs. El Chupón fue de 0.83. Los géneros de hongos del suelo que se encontraron en La Laguna coinciden en 67-75% con los encontrados en suelos desérticos de Israel, pero en La Laguna la estructura de los géneros de hongos es distinta; aquí domina Fusarium y aparecen nuevos géneros, como Trichoderma. Los cambios en la micobiota del suelo pueden haber ocurrido por la actividad agrícola en los últimos 50 a os. This study was carried out in agricultural soils in La Laguna, Coahuila - Durango, Mexico (annual precipitation 80-250 mm). The structure of soil fungal genera of three field soil was studied. In soil of Tierra Blanca, an orchard pecan of 51 years, there were isolated 23 genera of soil fungi, and only 12 genera of other two field soils (El Chupón, a pecan orchard of 14 years, and San Jorge, culturing with alfalfa). For each genus of soil fungi there were calculated the Importance Value Index (I V I). The genus Fusarium showed the greater I V I of the three field soils (71-98). The diversity (Shannon's index) of genera of fungi was different from each soil according to confidence intervals (95%), with values of 1.89, 1.72 y 1.19 for Tierra Blanca, El Chupón and San Jorge, respectively. Additional ecological indexes were c
Evaluación de ácido acético como fumigante de mosquita blanca Bemisia tabaci (Gennadious) en laboratorio y campo
Samaniego Gaxiola, José Alfredo;Amaya Carrillo, José Emmanuel;Puente Manríquez, José Luis;
Revista mexicana de ciencias agrícolas , 2012,
Abstract: the aim of this work was to assess the capacity of acetic acid (aa) like fumigant against bemisia tabaci (silverleaf whitefly) which is a pest of national importance. in laboratory, the bug was fumigated with three doses-time regimes: (both media), low dose-long time and high dose-short time. in field, squash leaves of four varieties were fumigated with 8, 16 and 32 μg ml-1 of aa during of 20, 40 and 60 min; additionally, it was assessed damage in foils (phytotoxicity) after fumigation. in laboratory, fumigation time > 15 min and 8μgml-1 of aa killed 100% of whitefly, while its survival was reduced 40% when fumigated eight hours with 2 μml-1 of aa; but control incubation (whitefly without fumigation) during ≥ 16 h also reduced its survival; meanwhile, with 8 and 16 μgml-1 of aa the pest survival was reduced since five minutes (~20-80%). in field, the whitefly survived ~ 40% in leaves of four varieties afterfumigating with aa(8-32 μg ml1)during20min, but pest practically did not survive when increasing fumigation time to 60 min. the leaves showed severe damage (phytotoxicity) > to 50% except in dose of 8μg ml-1 at 20 min with damage of - 20%. alternative to use of aa like fumigant are discussed.
Evaluación de ácido acético como fumigante de mosquita blanca Bemisia tabaci (Gennadious) en laboratorio y campo Assessment of acetic acid like fumigant of silverleaf whitefly Bemisia tabaci (Gennadious) in laboratory and field
José Alfredo Samaniego Gaxiola,José Emmanuel Amaya Carrillo,José Luis Puente Manríquez
Revista mexicana de ciencias agrícolas , 2012,
Abstract: El objetivo de este trabajo fue evaluar la capacidad del ácido acético (AA) como fumigante en contra de Bemisia tabaci (moquita blanca) que es un plaga de importancia nacional. En el laboratorio, se fumigó el insecto con tres regímenes de dosis - tiempo: (ambos medios), baja - largos y altas - cortos. En el campo, las hojas de calabaza de cuatro variedades fueron fumigadas con 8, 16 y 32 μg ml-1 de AA en tiempos de 20, 40 y 60 min; adicionalmente, se evaluó el da o en las hojas (fitotoxicidad) después de fumigarse. En el laboratorio, tiempo de fumigación > 15 miny 8 μg ml-1 de AA mató 100% de la mosquita, mientras que, su supervivencia se redujo 40% al fumigarla ocho horas con 2 μg ml-1de AA; pero la incubación del testigo (mosquita sin fumigar) por ≥ 16 h también redujo su supervivencia; entretanto, con 8 y 16 μml-1 de AA se redujo la supervivencia del insecto desde los cinco minutos (~20-80%). En el campo, la mosquita sobrevivió ~ 40% en las hojas de las cuatro variedades después de fumigarse con AA(8-32 μgml-1) durante 20 min, pero el insecto prácticamente no sobrevivió al aumentar el tiempo de fumigación a 60 min. Las hojas mostraron un da o severo (fitotoxicidad) > al 50% excepto en la dosis de 8 μg ml-1 a los 20 min con un da o de ~ 20%. Se discuten alternativas del empleo del AA como fumigante. The aim of this work was to assess the capacity of acetic acid (AA) like fumigant against Bemisia tabaci (silverleaf whitefly) which is a pest of national importance. In laboratory, the bug was fumigated with three doses-time regimes: (both media), low dose-long time and high dose-short time. In field, squash leaves of four varieties were fumigated with 8, 16 and 32 μg ml-1 of AA during of 20, 40 and 60 min; additionally, it was assessed damage in foils (phytotoxicity) after fumigation. In laboratory, fumigation time > 15 min and 8μgml-1 of AA killed 100% of whitefly, while its survival was reduced 40% when fumigated eight hours with 2 μml-1 of AA; but control incubation (whitefly without fumigation) during ≥ 16 h also reduced its survival; meanwhile, with 8 and 16 μgml-1 of AA the pest survival was reduced since five minutes (~20-80%). In field, the whitefly survived ~ 40% in leaves of four varieties afterfumigating with AA(8-32 μg ml1)during20min, but pest practically did not survive when increasing fumigation time to 60 min. The leaves showed severe damage (phytotoxicity) > to 50% except in dose of 8μg ml-1 at 20 min with damage of - 20%. Alternative to use of AA like fumigant are discussed.
Asociación entre pudrición texana (Phymatotrichopsis omnivora) e insectos barrenadores del nogal (Carya illinoensis)
Samaniego-Gaxiola, José Alfredo;Ramírez-Delgado, Manuel;Pedroza-Sandoval, Aurelio;Nava-Camberos, Urbano;
Agricultura técnica en México , 2008,
Abstract: euplatypus segnis (chapuis) (coleoptera: platypodidae) causes severe damage to pecan (carya illinoensis) trees at coahuila, mexico. the present study was carried out during 1999-2001 in a 90 ha pecan orchard, divided in eight lots, during 1999-2001. the trees were counted and clasified in four categories: attacked by borer insects and with symptoms of cotton root rot (phymatotrichopsis omnivora); only attacked by borer insects: only with symptoms of p. omnivora; and without pest neither disease. the attack by borer insects was significantly more frequent in pecans showing symptoms of p. omnivora than in those without symptoms. the dispersion of the pest adjusted to a logistic model, with r2 values of 0.871, 0.788 and 0.803 in 1999-2001, respectively. the absolute rate of dispersion of the borers was estimated at 2000-1999, 2001-2000 for each lot and year. the highest dispersion rates were observed in coinsidence with a soil moisture deficit in the orchard. the results indicate that frecuency of attack of the borers increases in tress with p. omnivora and irrigation deficit.
Nuevos realismos y sociedades complejas
Mario Samaniego
Cultura-Hombre-Sociedad , 2003, DOI: 10.7770/cuhso-v7n1-art195
Abstract: Las relaciones entre ciencia y sociedades complejas conforman el trasfondo de este texto, en el cual se reflexiona sobre el diálogo, tensión o escisión entre la ciencia entendida ya como dominio de lo público, como bien público y la sociedad civil en la que conviven grupos e individuos con identidades y concepciones de vida diversas e incluso confrontadas. Para ello, se describen ciertos hitos que dan cuenta de los cambios que tanto al interior de la epistemología,filosofa y teoría social como en la vida se han ido gestando en la modernidad tardía, los cuales al menos potencialmente abocan los esfuerzos tanto en el plano teórico como en el social a trabajar en pos del diálogo. Sin embargo, pareciera, que existiendo la oportunidad de establecer una relación deliberativa entre ciencia y sociedad, ésta por el momento no se da.
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