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

Grassland management practices that improve carbon uptake by increasing productivity or reducing carbon losses can lead to net accumulation of carbon in soils. A study was conducted to quantify the amounts of shoots and roots biomass of Brachiaria grass cultivars and their effects on soil carbon in two sites, Ithookwe and Katumani in semi-arid tropical Kenya. The grass cultivars were Brachiaria decumbens cv. Basilisk, B. brizantha cvs. Marandu, MG4, Piatã and Xaraes, B. humidicola cv. Llanero and B. hybrid cv. Mulato II. These were compared with two locally cultivated grasses (Chloris gayana cv. KAT R3 and Pennisetum purpureum cv. Kakamega 1). The grass treatments were evaluated with fertilizer application (40 kg P applied at sowing and 50 kg N ha-1 in each wet season) and with no fertilizer application. Shoots biomass of the Brachiaria cultivars ranged from 3.0 to 11.3 t ha-1 and 5.5 to 8.3 t ha-1 at Ithookwe and Katumani sites respectively in year 1. The highest shoots biomass recorded at Ithookwe was from cv. Piata while cv. MG4 gave the highest biomass at Katumani. Similar trends were recorded in year 2 of growth though the shoots biomass was lower at Katumani. However, the yields were significantly lower than those recorded from control, Napier grass in both years. The cv. Marandu, Xaraes, Basilisk and Piata had higher roots biomass than the controls (Rhodes grass and Napier grass) indicating greater potential for the Brachiaria grasses to sequester more carbon in the soil. The results of this study indicate that introduction of Brachiaria grasses in the semi-arid tropics of Kenya and in other similar environments can help increase soil carbon stocks that would mitigate the adverse effects of climate change and have greater economic returns. 

Tillage practices influence soil physical, chemical and biological qualities which in-turn alters plant growth and crop yield. In the Northern Guinea Savanna (NGS) ecological zone of Nigeria, agricultural production is mainly constrained by low soil nutrient and water holding capacity, it is therefore, imperative to develop appropriate management practices that will give optimal soil hydro-physical properties for proper plant growth, effective soil and water management and environmental conservation. This study investigated the effect of three tillage practices (no till, reduced till and conventional till) and four cover crops (Centrosema pascuorum, Macrotyloma uniflorum, Cucurbita maxima and Glyine max) and a bare/control (no cover crop) on some soil physical properties of a Typic Haplusult during the rainy seasons of 2011, 2012 and 2013 in Samaru, NGS ecological zone of Nigeria. The field trials were laid out in a split plot arrangement with tillage practices in the main plots and cover crops in the subplots, all treatments were replicated three times. Auger and core soil samples were collected at the end of each cropping season each year in three replicates from each treatment plot at four depths (0-5, 5-10, 10-15 and 15-20 cm). Particle size distribution, bulk density, total pore volume and water retention at various soil matric potentials were determined using standard methods. Data obtained were compared with optimum values and fitted into a RETC computer code for quantifying soil hydraulic behavior and physical quality. Results showed that different tillage practices had varied effect on soil physical properties. No-till had the highest water holding capacity at most suction points evaluated, it had 4.3 % and 12.9 % more soil moisture than the reduced till  and conventionally tilled systems across all matric potentials while Centrosema pascuorum (3.1%) and Cucurbita maxima (5.5%) were best among evaluated cover crops in retaining soil moisture content compared to the bare plots at -33kPa matric potential. Generally the Dexter S value used as an index for soil physical quality ranged within the limits of very good to good soil physical quality irrespective of the tillage practice, cover crops grown or depth of soil sampling. However the conventional tillage practice and soil under no cover crop had adverse effect on soil structural stability, placing them at a high risk of soil degradation. Indicators like Macro porosity, Air capacity, relative field capacity and Plant available water capacity were all within the optimal range for normal plant growth. The RETC computer code well described soil hydraulic parameter regardless of the treatments imposed on the soil.  

Las bacterias promotoras de crecimiento en plantas (BPCP) son un grupo de diferentes especies de bacterias que pueden incrementar el crecimiento y productividad vegetal. Las cuales pueden beneficiar a las plantas a través de su propio metabolismo bacteriano (solubilizando fosfatos, produciendo hormonas o fijando nitrógeno). En la actualidad la desertificación es un fenómeno creciente en todo el mundo, la repoblación forestal es una de las soluciones comunes para combatir este problema. Los árboles destinados a la reforestación son inicialmente cultivados en invernaderos o viveros. Entre numerosas prácticas de reforestación, una alternativa que existe es la inoculación con BPCP. Una especie forestal es Olneya tesota que es endémica del desierto de Sonora, la cual se encuentra en peligro de extinción. El objetivo consistió en evaluar el efecto de bacterias promotoras del crecimiento de plantas Rhodococcuis fascians y Azospirillum halopraeferens en la germinación y emergencia de Palo fierro bajo cuatro concentraciones salinas (0, 0.25, 0.5 y 0.75 M de NaCl) en condiciones de invernadero. Se obtuvieron semillas de palo fierro de la región de Santa Ana, Sonora. Bajo condiciones de invernadero se evaluó el porcentaje de emergencia, tasa de germinación, altura, longitud radicular de planta, peso fresco y seco de planta, número de células bacterianas adheridas al sistema radicular, peso fresco y seco de la raíz. Los resultados indican que, el porcentaje de germinación y las demás variables evaluadas a los 18 meses, disminuyeron conforme la salinidad se incrementa. Sin embargo, estas cambiaron positivamente en aquellas plantas inoculadas con las bacterias R. fascians y A. halopraeferens.

El conocimiento de la digestibilidad de los alimentos es básico para establecer su valor nutritivo y biodisponibilidad de los nutrientes para ello se han utilizado numerosos análisis de laboratorio para estimar la digestión ruminal e intestinal del alimento como son in vitro (Produccion de gas y Daisy) e in sacco, para ser comparadas con el método in vivo. El sorgo presenta el mayor (P<0.01) contenido de almidón, mientras que la FND fue mayor (P<0.01) para el maíz, la MSd fue similar (P=0.93) para ambos cereales, la digestión de la PC fue mayor (P<0.01) para el sorgo con respecto al maíz, mientras que para la proteína no degradable en rumen (PNDR) y la proteína degradable en intestino (PDI) no se encontraron diferencias (P>0.05) entre cereales. Con lo que respecta a los métodos de digestibilidad, la MSd fue menor (P<0.01) para el in vivo con respecto al resto de los métodos, la digestión de la PC tanto en rumen como en intestino fue mayor (P>0.01) para los métodos in sacco e in vitro (Daisy). La producción de AGV´S fue similar para ambos cereales. Las técnicas in situ e in vitro (DaisyII®) permiten determinar la digestibilidad de forma rápida y sencilla comparado con los métodos convencionales. El molido del sorgo mejora su valor alimenticio aumentando su digestibilidad, lo que representa una alternativa ante el maíz para la alimentación de terneros en engorda.

Agroforestry systems (AFS) are policultures with at least one tree species. These systems provide various ecosystem services, income increments and food safety. These ecosystem services include biodiversity conservation, carbon sequestration, reduction of crop diseases, increased biological controls, biological nitrogen fixation and nutrient cycling. A review of potential ecosystem services of AFS on Southern Brazil is presented. In addition, the potential of carbon uptake through conversion to AFS is estimated. The predominant AFS are agroforestry with yerba mate (Ilex paraguariensis A. St. Hil.), silvopastures, citrus and banana orchards, and the palm açaí-juçara (Euterpe edulis Mart.). Considering the conversion of conventional systems to AFS, the silvopastures present the greatest carbon sequestration potentiality due to the great area used for cattle ranching. The conversion of citrus and banana cropping also present great carbon uptake potential besides reducing fungal and bacterial diseases. Southern Brazil presents more than 15 million hectares which could be converted into silvopasture and other AFS by taking as a model the already well-established experiences. Moreover, AFS has become a strategy for forest restoration. There are no negative trade-offs related to the silvopasture and citrus agroforestry adoption. The reasons for the low adoption of AFS are discussed.

El maíz es el forraje más importante en la alimentación del ganado, debido a su mayor contenido de energía, sin embargo, se caracteriza por su amplia gama de variedades y la posibilidad de generar una gran cantidad de productos finales. El objetivo del presente estudio fue evaluar y comparar el rendimiento, composición química y producción de gas in vitro tanto en fresco como henificado de un maíz criollo local amarillo y seis variedades de maíces híbridos amarillos (HIT13, CML460, PIONER, COBRE, CDMO80001 y CLO80902). El rendimiento en fresco y en seco no mostró diferencias entre tratamientos (P ˃ 0.05), para la composición química (g kg-1 MS) se tuvieron diferencias (P ˂ 0.05) para el contenido de proteína por método de conservación vario de 59.87 a 59.61 g kg-1 MS, por metodo, FND de 591 a 686 g kg-1 MS por variedad y por método de 619 a 639 g kg-1 MS, FAD de 298 a 345 g kg-1 MS por variedad y por método de 317 a 340 g kg-1 MS; LAD de 58 a 41 g kg-1 MS por variedad y por método de 41 a 57 g kg-1 MS respectivamente, en la producción de gas in vitro acumulada (ml gas /g MS) no se observaron diferencias  (P>0.05) para la producción total de gas entre variedades y método de conservación. Se concluye que de acuerdo con los resultados obtenidos, las variedades estudiadas presentan los mismos rendimientos tanto en heno como en fresco. El rendimiento, la producción de gas in vitro y la producción de gas relativa no se vieron afectados por el método de conservación, ni por las variedades empleadas.

La cebada maltera (Hordeum vulgare L.) de temporal (secano) ha sido sembrada tradicionalmente con el sistema de siembra al voleo. Este sistema ha generado problemas de erosión del suelo por escurrimiento y baja productividad en Zacatecas, México. El Instituto Nacional de Investigaciones Forestales y Agropecuarias desarrolló una tecnología alterna llamada siembra en surcos a doble hilera y pileteo (SSDHP) para este cultivo. Los objetivos de esta investigación fueron evaluar el grado de adopción de SSDHP, caracterizar a los usuarios de la tecnología e identificar los factores asociados con la adopción de esta tecnología en Zacatecas, México. La información se recabó en 2009 y 2010 por encuesta aplicada a 135 productores en nueve municipios de Zacatecas. Se estimó un índice de adopción de 27 % para esta tecnología. Los adoptantes tenían más experiencia en el cultivo, mayor nivel educativo que otros grupos de productores y mayor superficie de siembra con este cultivo. Los productores que adoptaron esta tecnología reconocieron que el SSDHP incrementó el rendimiento, redujo la cantidad de semilla para la siembra, y disminuyó costos de producción. Se determinó que los factores que limitan la adopción de la tecnología SSDHP en Zacatecas son, principalmente, la falta de recursos económicos, la reducida disponibilidad de maquinaria agrícola especializada para realizar SSDHP y la poca o nula asistencia técnica.

Agricultural and cocoa agroforestry systems are important for food production and biodiversity conservation. Among this diversity there is a group of fungi of the genus Trichoderma that present antagonistic effects against phytopathogens and this action can be used as a form of biological control of plant pathogens. In the agroforestry-cacao system the diseases with the highest frequency and with the greatest impact on cocoa production (Theobroma cacao) are black rot (Phytophthora spp.), Broom broom (Moniliophthora perniciosa) and moniliasis (Moniliophthora roreri). The objective of this work was to perform an analysis of the main theoretical and practical aspects about the genus Trichoderma and its role in agriculture as an antagonistic agent. One of the microscopic features in the delimitation of the genus, especially by the presence of structures called phalid. The antagonistic mechanisms used by Trichoderma spp. Are described as competition, antibiosis and mycoparasitism. Mycoparasitism is having a relevance on the implications of extracellular enzymes such as chitinases, cellulases, β-1-3-glucanases and proteases that lyse or digest the walls of fungi, Moniliophthora roreri disease. This fungus can inhibit the growth of other fungi and bacteria by producing several volatile and non-volatile secondary metabolites. On the other hand, it participates in the production of regulators of growth and stimulation of the division, differentiation and cellular growth in the plant by the elicitor agent. Trichoderma species that are commercialized for biological control, growth promoter and biofertilizer are T. viride, T. polysporum and T. harzianum. The T. virens and T. harzianum species are most used for the antagonistic control of M. roreri, Phytophthora spp., and M. perniciosa in agroforestry-cacao systems (Theobroma cacao L.) with optimal results to the inhibitory effect for these diseases.

Small-grain cereals are promoted as forage alternatives that may substitute for other traditional crops when short cycle forages are required for cattle feeding. The objective of the work was to assess in vitro the nutritive quality, ruminal fermentation kinetics and digestibility by the gas production technique of forage from common oat (Avena sativa cv. Canadiense) = AC, black oat (Avena strigosa cv. Saia) = AN, Triticale (×Triticosecale Wittm. cv. Criollo) = T, and rye (Secale cereale of national production) = C. The forage crops were sown in 250 m2 plots, harvested and sampled 72 days after sowing in a completely randomised design with five replicates. Both oat species (AC and AN) had significantly higher crude protein and neutral detergent fibre contents (P<0.05) compared to T and C. In vitro gas production showed a higher fermentation rate for black oat and common oat, with no differences for in vitro digestibility (P>0.05) for the evaluated forages. There were also no differences in the estimated ME content (P>0.05). Results indicate that black and common oats are forages with a better nutritive quality when harvested at a similar time compared to triticale and rye forage.