The successful achievement of a highly productive understorey pasture in silvopastoral systems depends on the use of well-adapted forage genotypes, showing good agronomic performance and persistence under shading and grazing. In this study, the herbage dry matter yield (DMY) and nitrogen nutrition dynamics were determined in three native warm-season grasses (Paspalum regnellii, Paspalum dilatatum and Paspalum notatum) and a forage legume (Arachis pintoi) under two shading levels compared with full sun. The experiment was conducted in the Campanha region, Bagé, state of Rio Grande do Sul, Brazil, during two evaluation cycles (2008/2009 and 2009/2010). Three shade cloth levels (0%, 50% and 80% of light restriction) were applied to the forage genotypes in a split plot design, in which shading levels were the main plot and forage genotypes were the subplots, with three replications. P. regnellii showed the highest accumulated DMY (1500 and 1700 g m-2, respectively, for the first and second evaluation cycles) at all shading levels and showed no DMY decreased under the heavy shade (80%). Average DMY over the four genotypes under the 50% shade level was higher or equal compared with full sun. Influence of rainfall was observed on the DMY performance of all genotypes: the positive effect of moderate shading (50%) on P. dilatatum and P. notatum DMY was associated to a low soil water availability status. Increased shading level resulted in high nitrogen nutrition index values on grasses, in comparison with full sun. All genotypes performed well under the moderate shading level, but the DMY of both P. regnellii and P. dilatatum and the herbage N content in P. notatum and A. pintoi of all genotypes stood out, showing that those main genotypes are promising to grow in silvopastoral systems at the Campanha region in southern Brazil.

A fim de avaliar os padrões de resposta de áreas cultivadas com cereais de estação fria destinados para pastagens e para produção de grãos em imagens de satélite, foram analisados perfis temporais de índice de vegetação por diferença normalizada (NDVI), adquiridos em 29 áreas cultivadas com trigo e azevém anual, nos Estados do Rio Grande do Sul e Paraná. Para cada área foi informada a espécie cultivada (trigo ou azevém anual) e a coordenada do ponto central da área adquirido por meio do Global Positioning System (GPS). Foram usadas as imagens do sensor MODIS (Moderate Resolution Imaging Spectroradiometer), com resolução espacial de 250 metros, sobre cada área monitorada, de onde os valores de NDVI foram extraídos. Os perfis temporais de NDVI mostraram que os cultivos de produção de grãos têm um comportamento espectral típico de cultivos agrícolas, enquanto que, nas áreas cultivadas para a produção de pastagem, não foi observado esse mesmo padrão. As diferenças nos padrões temporais observadas se devem a modificações que o pastoreio impõe na fenologia e na morfologia dessas plantas.

In order to evaluate the satellite image patterns between such cool season cereals cultivated areas intended for grazing or grain production, Normalized Difference Vegetation Index (NDVI) temporal profiles were analyzed. This data was acquired from twenty nine wheat and annual ryegrass cultivated areas in the states of Rio Grande do Sul and Paraná. For each area, the cultivated species (wheat or ryegrass), as well as the respective central point coordinates, acquired via Global Positioning System (GPS) was informed. NDVI values were extracted over each monitored area from MODIS (Moderate Resolution Imaging Spectroradiometer) sensor images, with spatial resolution of 250 meters. The NDVI temporal profiles showed that grain production areas have a typical agricultural field spectral pattern. The same pattern was not observed for the grazing pasture areas. The differences observed in these temporal patterns are defined by the changes that grazing has imposed on the phenology and morphology of these plants.

Objetivou-se avaliar o comportamento de espécies forrageiras (Brachiaria decumbens cv. Basilisk, Brachiaria brizantha cv. Marandu, Panicum maximum cvs. Tanzânia, Aruana e Mombaça, Hemarthria altissima cv. Florida; Paspalum notatum cv. Pensacola, Axonopus catharinensis, Cynodon sp. híbrido Tifton-85; Arachis pintoi cvs. Alqueire e Amarillo) submetidas a diferentes níveis de luminosidade produzidos por árvores de Pinus taeda (céu aberto; 9 m entre linhas e 3 m entre árvores; e 15 m entre linhas e 3 m entre árvores). Avaliaram-se a produção de MS, a relação lâmina foliar:colmo (L:C), o nível de florescimento das plantas, os teores de PB e FDN e as variáveis meteorológicas e do solo, na projeção da copa e no meio da entrelinha de árvores, de cada parcela. A produção de MS foi afetada negativamente pelo sombreamento, por outro lado, o teor de PB foi maior nas parcelas sombreadas em relação ao pleno sol. Além da menor radiação, a velocidade do vento e a temperatura do solo nas parcelas sombreadas foram menores naquelas a sol pleno. O teor de FDN não diferiu significativamente entre os níveis de luminosidade, embora a relação L:C tenha sido maior na entrelinha do 9 × 3 em relação àquela a céu aberto. As espécies forrageiras mais produtivas e com maior potencial para utilização em ambiente silvipastoril foram: Axonopus catharinensis e Brachiaria brizantha cv. Marandu.

The behavior of forage species (Brachiaria decumbens cv. Basilisk, Brachiaria brizantha cv. Marandu, Panicum maximum cvs. Tanzânia, Aruana and Mombaça, Hemarthria altissima cv. Florida; Paspalum notatum cv. Pensacola, Axonopus catharinensis, Cynodon sp. hybrid Tifton-85; Arachis pintoi cvs. Alqueire and Amarillo) submitted to different radiation levels produced by Pinus taeda trees (open sky, 9 meters between tree rows and 3 meters within the row and 15 meters between tree rows and 3 meters within the row) was evaluated in this trial. Variables such as forage biomass production, leaf to stem ratio, plant height, flowering rate, nutritional value of leaves, meteorological and soil variables under the tree canopy and between rows were evaluated. The forage production was negatively affected by shading, but forage crude protein increased with shading compared with open sky. Besides the decrease in radiation under trees, lower wind speed and soil temperature were observed when compared to open sky plots. The NDF (neutral detergent fiber) of leaves was not affected by the radiation levels, although leaf to stem ratio was greater in the middle of the 9 × 3 m plot when compared to open pasture. The most productive species and those that showed potential yield to grow in silvipastoral system were Axonopus catharinensis and Brachiaria brizantha cv. Marandu.

Avaliou-se o efeito do sombreamento provocado por duas densidades arbóreas em uma floresta de Pinus elliottii Engelm. com 10 anos de idade sobre o rendimento e o valor nutritivo da forragem de três gramíneas de ciclo hibernal. Como tratamentos, avaliou-se a combinação de dois fatores (3 x 3) em um delineamento experimental de parcelas subdivididas com três repetições, no qual as parcelas foram as condições luminosas (proporcionadas por duas densidades arbóreas: 555 e 333 árvores/ha e luz solar plena) e as subparcelas as espécies forrageiras azevém-anual (Lolium multiflorum Lam.); aveia-preta (Avena strigosa Schreb.); e aveia-branca (A. sativa L.) cv. Fapa 2. A semeadura foi realizada entre 25/7/2005 e 5/8/2005 e entre 26 e 27/4/2006. O rendimento de matéria seca foi estimado em avaliações durante o estádio vegetativo (aos 104 dias após a semeadura em 2006) e em pleno florescimento (aos 132 e 170 dias, em 2005 e 2006, respectivamente). O valor nutritivo da forragem foi avaliado considerando os teores médios de proteína bruta (PB) e a digestibilidade in vitro da matéria orgânica (DIVMO). O sombreamento moderado reduziu em 57% o rendimento médio de forragem dos três genótipos avaliados, mas aumentou em 2,3% o teor de proteína bruta (PB) e em 5,5% a digestibilidade in vitro (DIVMO) quando as plantas estavam em florescimento pleno. Entre as espécies forrageiras avaliadas, a aveia-branca e a aveia-preta apresentam maior potencial para utilização em sistemas silvipastoris na Região Sul.

It was evaluated the shading effect induced by two tree densities of a ten-year-old slash pine (Pinus elliottii Engelm.) forest, and at full sun, on forage dry matter yield and nutritive value of three cool-season annual grasses. Treatments were a combination of two main factors: a) three light conditions induced by two tree densities (333 e 555 stems/ha) and at full sun; b) three cool-season annual forage grasses: Italian ryegrass (Lolium multiflorum Lam.), common oat (Avena sativa L.) cv. Fapa-2, and black-oat (Avena strigosa Schreb.). A split-plot experimental design, with three replications, was used. The main plots were the light conditions affected by tree density and the subplots were the different forage species. Sowing dates were from July 25 to August 5, 2005 and April 26 and 27, 2006. In order to determine forage DM yield, plants were hand-clipped at the vegetative stage (104 days after sowing, in 2006) and at full bloom (132 and 170 days, in 2005 e 2006, respectively). Forage nutritive value was accessed by determining crude protein (CP) concentration and in vitro organic matter digestibility (IVOMD). Results showed that when plants were at the full bloom stage and under moderate shading, forage DM yield was reduced by 57%, forage CP content was increased by 2,3%, and IVOMD was raised by 5,5%, compared to plants at full sun. In terms of their potential utilization, common oat and black-oat show promise for regional silvopastoral systems in southern Brazil.

O objetivo deste trabalho foi avaliar cinco sistemas de controle da vegetação nativa e os danos provocados por bovinos e ovinos em três populações de eucalipto. O delineamento experimental foi em parcelas subdivididas, com dois blocos completos. Os tratamentos foram: a) três densidades de Eucalyptus saligna Smith. (204, 400 e 816 árvores/ha) nas parcelas principais e b) cinco sistemas de controle da vegetação nativa (sem controle, herbicida pré-emergente, herbicidas pré e pós-emergentes, pastejo com bovinos e com ovinos) nas subparcelas. O pastejo com bovinos ou ovinos foi mais eficiente na redução da vegetação nativa que nos demais tratamentos. Os bovinos danificaram mais as árvores que os ovinos. Existe estreita relação entre a altura das mudas de eucalipto e os danos causados pelos bovinos e ovinos no momento da introdução destes animais no sub-bosque.

The objective of this work was to evaluate five control systems of native vegetation and the damages caused by cattle and sheep to trees of three eucalyptus populations. A split-plot experimental design in two randomized complete blocks was used. Treatments were a) three populations of Eucalyptus saligna Smith. (204, 400 and 816 plants/ha) as the main plots; b) five control systems of the native vegetation (without control, pre-emergent herbicide, pre and post-emergent herbicides, cattle grazing or sheep grazing) as subplots. The cattle and sheep grazing were the most efficient than any other treatments. The cattle caused more damage to the trees than sheep did. There is a close relation between tree height and damages caused by cattle and sheep at the moment of the introduction of these animals in the underneath forest.