Alexandre Costa Varella

Influência da luminosidade no comportamento de onze espécies forrageiras perenes de verão

Objetivou-se avaliar o comportamento de especies forrageiras (Brachiaria decumbens cv. Basilisk, Brachiaria brizantha cv. Marandu, Panicum maximum cvs. Tanzânia, Aruana e Mombaca, Hemarthria altissima cv. Florida; Paspalum notatum cv. Pensacola, Axonopus catharinensis, Cynodon sp. hibrido Tifton-85; Arachis pintoi cvs. Alqueire e Amarillo) submetidas a diferentes niveis de luminosidade produzidos por arvores de Pinus taeda (ceu aberto; 9 m entre linhas e 3 m entre arvores; e 15 m entre linhas e 3 m entre arvores). Avaliaram-se a producao de MS, a relacao lâmina foliar:colmo (L:C), o nivel de florescimento das plantas, os teores de PB e FDN e as variaveis meteorologicas e do solo, na projecao da copa e no meio da entrelinha de arvores, de cada parcela. A producao de MS foi afetada negativamente pelo sombreamento, por outro lado, o teor de PB foi maior nas parcelas sombreadas em relacao ao pleno sol. Alem da menor radiacao, a velocidade do vento e a temperatura do solo nas parcelas sombreadas foram menores naquelas a sol pleno. O teor de FDN nao diferiu significativamente entre os niveis de luminosidade, embora a relacao L:C tenha sido maior na entrelinha do 9 × 3 em relacao aquela a ceu aberto. As especies forrageiras mais produtivas e com maior potencial para utilizacao em ambiente silvipastoril foram: Axonopus catharinensis e Brachiaria brizantha cv. Marandu.

Forage yield and nitrogen nutrition dynamics of warm-season native forage genotypes under two shading levels and in full sunlight

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, Bage, 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.

Uso de bovinos e de ovinos como agentes de controle da vegetação nativa sob três populações de eucalipto

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.

Caracterização espectral multitemporal dos cereais de estação fria em imagens de satélite com média resolução espacial

In order to evaluate the satellite image patterns between such cool season cereals cultivated areas intended for grazing or grain pro ductio n, No rmalized Differe nce

Silvopastoral systems in the cold zone of Brazil.

The cold zone of Brazil occupies approximately 6 % of the national territory and is located between latitudes 24° S and 33° S. In this area, extensive cattle and sheep farming systems and conventional cropping and forestry are predominant. With the end of government subsidies by the decade of 1980s, an increase in farming production costs, a decrease of native forest covering, an increase of degraded areas in agriculture and livestock farming systems and a mismatch between timber national supply and demand after 1990s, an opportunity arises for integrate forestry with livestock and agriculture activities in Brazil, particularly in the southern. This chapter initially reports key events over the last three decades that have supported the increasing interest of farmers and enterprises on agroforestry activities, with focus on silvopastoral systems in the cold area of Brazil. Then, relevant advances on silvopastoral systems from research and extension services were reported, highlighting the screening of shaded adapted forage plants and management, trees species screening for silvipastoral systems and animal performance and behaviour under trees. Finally, the chapter analyses the existent opportunities to increase silvopastoral areas in southern Brazil and future challenges for research, development and technology transfer.