This study investigated removal of sulfide and p-cresol linked to denitrification in laboratory-scale upflow anaerobic granular sludge bed (UASB) bioreactors. Three parallel denitrification bioreactors were run for nine months, which were operated under chemolithoautotrophic conditions (i.e., using sulfide as electron donor -e-donor- and bicarbonate as C source); heterotrophic conditions (with p-cresol as e-donor and C source), and mixotrophic conditions (utilizing both sulfide and p-cresol as electron donors), respectively. The average hydraulic retention time and nitrate load applied to the bioreactors was 13.4 h and 1,240 mg N-NO3/l/day, respectively. The nitrate removal efficiency was 89, 95 and 99%, respectively, for the chemo-, hetero- and mixotrophic reactors. The mixotrophic UASB removed both sulfide and p-cresol almost completely, indicating that simultaneous removal of the inorganic and organic e-donors occurred. Nitrite was seldom observed as an intermediate. N2O gas and methane concentrations in the biogas were also negligible. These results indicate that mixotrophic denitrification with phenols and sulfide is feasible in high rate UASB reactors.

La radiación gamma puede ser utilizada para conocer el rango de radiosensibilidad (RRS) en pastos con fines de mejoramiento genético por mutagénesis. El pasto rosado es una especie invasora que puede ser mejorada en valor nutricional u otras características. El objetivo de este estudio fue determinar la dosis óptima de radiación gamma para inducir mutaciones efectivas en pasto rosado mediante dosis letal media (DL50) y reducción media de crecimiento (GR50). El estudio fue realizado en campo, laboratorio e invernadero. De acuerdo a la media ponderada de las variables incluidas en LD50 y GR50, la dosis óptima se estimó a los 304 Gy. Los resultados de este estudio permiten conocer el RRS para la aplicación de radiación gamma óptima con Co60, que pueda inducir características futuras de interés económico y ecológico en el pasto rosado.

The use of entomopathogenic fungi is a common practice for integrated pest management. It has recently been observed that they also play a role as growth promoters and plant disease antagonism. In this study, the effect of inoculation with two strains of Beauveria bassiana [(Bals.-Criv.) Vuill. 1912] (strains BB42 and BB09) and two strains of Metarhizium anisopliae [(Metschn.) Sorokīn 1883] (strains MA25 and MA28) on the percentage of seed germination and development of chilli seedling (Capsicum annuum L.) was evaluated. In the in vitro test, we did not find significant differences between percentages of germination, but in the in vivo test, differences were significant, where sMA28 and BB09 strains obtained the highest germination percentage (85%). It was also found that seedlings inoculated with entomopathogenic fungi generate longer roots and produced more biomass in both tests, as well as lower percentages of contaminated seeds in in vitro and in vivo tests. All strains evaluated had inhibitory effects against two seed borne fungi isolated from contaminated seed, belong to genus Alternaria sp.

ResumenEl presente trabajo pretende desarrollar una alternativa de producción en cultivos protegidos a productores de escasos recursos de México. Los objetivos fueron: i) determinar la capacidad de resistencia de culmos de bambú de cuatro especies: Bambusa oldhamii Munro, Bambusa vulgaris var. vulgaris Schrad, Bambusa vulgaris 'Striata' y Gigantochloa verticillata Willd.; ii) diseñar un prototipo de invernadero para zonas áridas con culmos de bambú; y iii) estimar el impacto ambiental en relación al CO2 involucrado. Los resultados de resistencia a la compresión muestran que las especies fueron estadística iguales, así como entre las secciones inferior, media y superior de los culmos; los valores promedios oscilaron de 645 kg cm -2 a 952.31 kg cm -2 . En flexión no se encontró diferencia significativa entre especies, solo en las secciones; se observa que la flexión disminuye hacia la parte superior de los culmos en las cuatro especies; los valores promedios encontrados oscilaron de 850.17 kg cm -2 a 1 927.63 kg cm -2 . En tensión la diferencia fue solo entre las secciones de los tallos en B. vulgaris var. vulgaris, en esta especie la sección inferior promedió 1 023 kg cm -2 y la superior 727 kg cm -2 . Con los datos de resistencia y características agronómicas Abstract This paper aims to develop a production alternative in protected crops for resource-poor farmers in México. The objectives were: i) determining the resilience of bamboo culms of four species: Bambusa oldhamii Munro, Bambusa vulgaris var. vulgaris Schrad, Bambusa vulgaris 'Striata' y Gigantochloa verticillata Willd.; ii) design a greenhouse prototype for arid zones with bamboo culms; and iii) to estimate the environmental impact in relation to involved CO2. The results of compressive strength show that species were statistically equal, as well as between the lower, middle and upper sections of the culms; the average values ranged from 645 kg cm -2 to 952.31 kg cm -2 . Regarding to bending, no significant difference was found between species, only in sections; it is observed that bending decreases towards the top of the culms in the four species; the found average values ranged from 850.17 kg cm -2 to 1 927.63 kg cm -2 . Regarding the tensión the difference was only between sections of the stems in B. vulgaris var. vulgaris, in this species the lower section averaged 1023 kg cm -2 and the top 727 kg cm -2 . Using resistance data and agronomic characteristics desirable for greenhouses in arid zones, the structural design was determined using STAAD.Pro ® V8i software. The prototype's construction specifications are exposed to detail so that it can be reproduced without complications by producers. Finally an environmental benefit is estimated in emissions of CO2 of 2847 kg in greenhouse construction of 135 m 2 compared to one of the same area made out of steel.