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Use of irrigation in forage production systems based on perennial C4 grasses has been limited because of inconsistent responses of biomass production to water. The effects of three different levels of irrigation on growth of Paspalum notatum (Bahia grass) and P. dilatatum (dallis grass) over two consecutive growing seasons were studied. The phenological state of the plants was inferred by the proportion of lamina and non-lamina components. While irrigation failed to increase annual dry matter yield of forage, phenological composition of forage was affected by irrigation with both species showing changes in distribution of dry matter accumulation among different above-ground plant parts. Future research on these species should study the effects of moisture deficit on phenology to better understand the effects of irrigation.

Las pasturas anuales de invierno son componentes estratégicos de los sistemas agropecuarios en Uruguay. El objetivo de este estudio fue evaluar el efecto de la fijación biológica de N de leguminosas en una mezcla con raigrás anual en contraste con la adición de fertilizante nitrogenado. El diseño experimental fue un diseño de bloques completos al azar con arreglo factorial 2 x 2 de los tratamientos, con dos tipos de pasturas: a) pastura de raigrás anual (Lolium multiflorum L.), y b) pastura mezcla de raigrás anual con dos especies de leguminosas anuales (Trifolium resupinatum L. y Trifolium vesiculosum L.); y dos niveles de fertilización con N: a) sin fertilizante, y b) 64 kg N ha-1. Las pasturas fueron pastoreadas con novillos Holstein. En verano se realizó un cultivo de Setaria italica para evaluar los efectos de los tratamientos en la producción de biomasa de este. La biomasa acumulada de las pasturas de invierno incrementó significativamente con fertilización de N (P ≤ 0.01), con un incremento de 1277 ± 322.5 kg MS ha-1. La pastura mezcla fertilizada con N produjo un mayor índice de nutrición nitrogenada que la pastura de raigrás anual. La biomasa aérea de raigrás presentó un incremento con el agregado de N; sin embargo, en las pasturas monofíticas de raigrás hubo un aumento del 47% de malezas. La ganancia media diaria de los novillos incrementó con la incorporación de leguminosas, con un promedio en las pasturas mezclas de 1,01 kg PV día-1. La adición de fertilizante nitrogenado permitió una mayor carga animal y una mayor producción animal en invierno. No se encontró un efecto de los tratamientos en la biomasa acumulada de S. italica. La incorporación de leguminosas al raigrás anual permitió una mayor ganancia diaria de peso vivo por animal, pero no produjo un efecto adicional sobre el cultivo sucesor de verano.

With the purpose of developing a methodology for the propagation in vitro of Eucalyptus grandis (former Hill Maiden), they were carried out investigations that embraced from the pretratamiento of the donating plants until the evaluation of the plants in vitro in the field. The results showed that the previous application of fungicides and insecticides to the plants donating 21-30 days before the establishment it increased the efficiency of this phase, in which the best results in the disinfection were obtained with the application of hipoclorito of sodium to 1.0% during 10 minutes. With the addition of 6-bencilaminopurina and sour naftalenacético (0.1 mg.l-1) in the multiplication phase buds of more quality were obtained, that showed 75% rooting when they were individualized and transferred to a means of cultivation with 0.3 mg.l-1 of AIB. The evaluations carried out in the field to the in vitro plants demonstrated a dynamics of very superior growth to those taken place starting from seeds. Key words: multiplication, rooting, in vitro plant

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