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El experimento se condujo para desarrollar una estrategia que determine con mayor precisión, mediante la combinación de indicadores edafoclimáticos y el análisis multivariado de componentes principales y conglomerados, la producción de semillas pratenses tropicales. Los datos se tomaron de fincas de semillas en regiones específicas de Cienfuegos, Villa Clara, Sancti Spiritus, Camagüey, Granma y Guantánamo. Las especies utilizadas fueron: Panicum maximum, Andropogon gayanus, Brachiaria decumbens, Brachiaria brizantha, Chloris gayana, y Cenchrus ciliaris. Los resultados mostraron la preponderancia de las variables precipitación total y en lluvia; temperatura máxima, mínima y media; profundidad del suelo, pedregosidad, fósforo y drenaje. El método de conglomerado produjo cuatro grupos: Cienfuegos; Guantánamo, Villa Clara y Camagüey; S. Spiritus y Granma. Estas variables explican 88.8 % de la variabilidad en el análisis de conglomerados. El análisis matemático mostró que no hubo relevancia para el rendimiento, que varió entre 147.8 y 240 kg/ha. Esto puede indicar que el comportamiento de las especies no varía de manera relevante entre regiones. Se concluye que el método combinado fue útil para estudiar la influencia de la combinación de factores edafoclimáticos, especies y regiones del país. [ABSTRACT FROM AUTHOR]

Se diseñó un experimento en el que se utilizó la metodología desarrollada por Torres et al. (2007), que permite conocer el índice de impacto La aplicación de esta técnica admite combinaciones de especies dentro de cada región edafoclimática. El índice de impacto depende de los indicadores de mayor preponderancia que aparecen en el análisis de los componentes principales y que se corresponden con los mismos El resultado genera valores que, de acuerdo con su jerarquía numérica, expresan el mayor o menor efecto de cada indicador por región Los datos provienen de fincas de semillas, ubicadas en regiones específicas de las provincias Cienfuegos, Villa Clara, Sancti Spíritus, Camagüey, Granma y Guantánamo. Las especies utilizadas fueron: Panicum maximum, Andropogon gayanus, Brachiaria decumbens Brachiaria brizantha, Chloris gayana y Cenchrus ciliaris. Los resultados mostraron la preponderancia de los factores precipitación total y en la época de lluvia, temperaturas máximas, media y mínima; profundidad efectiva, pedregosidad y horas luz. Los indicadores de la primera componente tuvieron más alto índice de impacto en Guantánamo, le siguieron Granma y Camagüey. Reflejaron menor valor en Cienfuegos con cifras más negativas. En el primer índice de impacto se encontraron 45.4 % de los indicadores de mayor preponderancia en el análisis de componentes principales. Andropogon gayanus alcanzó los mayores valores en Guantánamo, Granma y Camagüey. Le siguieron Panicum maximum, Cenchrus ciliaris y Brachiaria brizantha, respectivamente. Este resultado indicó una relación más estrecha entre las especies en las regiones señaladas. Se concluye que los métodos matemáticos utilizados fueron potenciados a partir de la determinación del índice de impacto. Se discute la importancia de la metodología utilizada, así como del estudio de las localidades y del posible efecto del índice de impacto en la interacción genotipo ambiente. [ABSTRACT FROM AUTHOR]

From August 2003 to December 2004 a field test was carried out during two rainy seasons in the Municipality of Cotaxtla, Veracruz, Mexico, in order to determine the effect of different treatments to control weeds on the production and quality of Gamba grass. A completely randomized block design with four replications was used. The treatments were: 1. Picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid) + fluroxypir (4-amino-3,5-dichloro-6-fluoro-2-pyridyloxyacetic acid) (40 g + 40 g/100 l water), 2. Picloram + 2,4-D (2,4-dichlorophenoxyacetic acid) (64 g + 240 g/100 l water) 3. Mowing with machete, and 4. Weedy check. The treatments were applied once per rainy season in the same experimental plots. Weed population density was determined before treatment application, whereas weed control and forage production and quality were evaluated at 42, 98, 160 and 223 days after application (DAA) during the first rainy season and at 34, 72, 112 and 163 DAA during the second one. The two herbicide treatments resulted in a higher weed control than the mowing treatment, which was reflected in the last treatment in a reduction of the forage production 17,4 to 66,6% lower than the average obtained with the herbicide treatments. During the lowest moisture periods, the crude protein content of the Gamba grass was significantly higher at least in one of the herbicide treatments in relation with the weedy check. [ABSTRACT FROM AUTHOR]

An assessment of different livestock alternatives for milk production including an improvement of native grasslands based on an association of Andropogon gayanus cv. CIAT 621 and climatic adaptation to Camagüey province northern savannas with dominant red brownish ferromagnesial fersialitic soil, was carried out. The alternatives applied were cattle fattening, and milk production associated to sheep breeding. A farm located in the area and showing all the tipical ecological characteristics mentioned above was selected for the study . Forage and other food balance was performed to obtain a positive response to grassland sowing and food supplementation, and a partial budget analysis for a net change in sach variant utilities was carried out. Estimates were made in USD according to the costs and price in 2003. In relation to fattening variants, sowwing of the associated grass in an extent of 25 and 40% within the area including food supplementation or not, achieved the highest net changes in utilities compared to milk production, while milk production associated to sheep breeding alternative showed better advantages for a 40% improvement of native grassland in both cases. Results concerning milk production indicated that the best options for cattle management and native grassland improvement based on grass association are cattle fattening with a 25 and 40% grassland improvement with or without food supplementation and milk production associated to sheep breeding with a 40% grassland improvement. [ABSTRACT FROM AUTHOR]

The behavior of six improved grassies under cutting on a lower-fertility red-brownish ferromagnesial fersialitic soil was studied. A completely randomized design with three replicas consisting in 0,25 ha spots under grazing conditions every 30 to 35 days during rainy season and 40 to 50 days during dry season with 12 lambs/ha load was applied. Grassy species were fertilized with N, P, and K at a ratio of 100; 80 and 100 kg/ha/year, respectively. Nitrogen was fractionated during the rainy season. Availability was measured by rotational grazing, and botanical composition was determined at the initial and final stages of the experiment. Andropogon gayanus cv. CIAT 621 showed the highest dry matter availability, followed by Brachiaria decumbens cv. CIAT 606, which showed no significant differences in relation to Andropogon in the first year during the rainy season and the second and third years during the dry season. In contrast, Brachiaria purpurascens cv. Aguada showed the worst behavior to the above mentioned index. Andropogon and Brachiaria 606 endurance was higher (P<0,001), but the other species population decreased by the third year. It is recommended to spread Andropogon gayanus cv. CIAT 621 and Brachiaria decumbens cv. CIAT 606 over the region due to edaphic and climatic conditions in this place. [ABSTRACT FROM AUTHOR]