Carlos Renato Tavares de Castro

Produção forrageira de gramíneas cultivadas sob luminosidade reduzida

The objective of this work was to evaluate the influence of three levels of artificial shade (0, 30 and 60%) on dry matter production, nitrogen content and morphological characteristics of six forage grasses (Andropogon gayanus cv. Planaltina, Brachiaria brizantha cv. Marandu, B. decumbens, Melinis minutiflora, Panicum maximum cv. Vencedor and Setaria anceps cv. Kazungula). A randomized block design, with split plots and four replicates, was used; the shading levels were allotted to the plots and the species to the split plots. The results showed that shading affected the production of dry matter, the nitrogen content and the morphological characteristics of the evaluated species. The production of forage was differentially affected by the shade. The dry matter production of P. maximum cv. Vencedor was 19.72% higher, at moderate shade than in broad daylight. The forage production of S. anceps cv. Kazungula, however, was not affected by the shade. The dry matter production of other species decreased with the reduction of the light. In all species there was an increase of N content and reduction of the content of dry matter of the forage, which became juicier in the shade. The morphological characteristics did not show a standard behavior, which varied according to the studied specie.

The growth dynamics in Brachiaria species according to nitrogen dose and shade

It was studied the effects of shading (0, 36 and 54%) and of four nitrogen doses (0, 50, 100 and 150 mg N/dm3 of soil) on the morphogenetic traits and on the tillering of grasses of Brachiaria genus (B. decumbens, B. ruziziensis and B. brizantha cv. Marandu and cv. Xaraes), cultivated in pots with 5 kg substrate. It was used a complete random design, in a 3 × 4 × 4 factorial scheme with three replications. Nitrogen promoted increase in leaf appearance rate and in average leaf blade length, whereas shading increased stem elongation rate. Leaf elongation rate and tillering varied with the interaction among shading percentages and nitrogen doses. Shading increased response efficiency of leaf elongation rate to nitrogen doses, but reduced for tillering, evidencing priority existing tillering growth in detriment to appearance of new tillers when there is light restriction for the plants. Phenotypic adjustments, in response to light reduction, indicate that the studied grasses present tolerance to moderate shading.Estudaram-se os efeitos do sombreamento (0, 36 e 54%) e de doses de nitrogenio (0, 50, 100 e 150 mg/dm3 de solo) nas caracteristicas morfogenicas e no perfilhamento de gramineas do genero Brachiaria (B. decumbens, B. ruziziensis e B. brizantha cvs. Marandu e Xaraes) cultivadas em vasos com capacidade para 5 kg de substrato. Adotou-se o delineamento inteiramente casualizado, em esquema fatorial 3 × 4 × 4 com tres repeticoes. O nitrogenio promoveu aumento na taxa de aparecimento de folhas e no comprimento medio das lâminas foliares, enquanto o sombreamento aumentou a taxa de alongamento do colmo. A taxa de alongamento de folhas e o perfilhamento variaram com a interacao entre as percentagens de sombra e as doses de nitrogenio. O sombreamento aumentou a eficiencia de resposta da taxa de alongamento de folhas as doses de nitrogenio, mas reduziu para o perfilhamento, evidenciando prioridade no crescimento de perfilhos existentes em detrimento do surgimento de novos perfilhos quando ha restricao de luminosidade para as plantas. Os ajustes fenotipicos, em resposta a diminuicao de luz, indicam que as forrageiras estudadas apresentam tolerância ao sombreamento moderado.

Características produtivas e nutricionais do pasto em sistema agrossilvipastoril, conforme a distância das árvores

The objectives of this work were to evaluate the effects of trees arranged in rows on yield and nutritional characteristics of Urochloa decumbens and to identify the average distance in which there is a better use of moderate shading in an agrisilvipasture system. The treatments consisted of distances from measure points to tree rows (0, 3, 6, 9, 12 and 15 m) and were distributed in randomized blocks, with four replicates. The tiller density, forage mass, forage accumulation rate and chemical composition of pasture were evaluated. The tiller density, forage mass and rates of forage accumulation increased with the distance from tree rows, reaching the highest values of 392 tillers m-2, 1,347 kg ha-1 and 30.1 kg ha-1 per day, respectively, at 9.1, 10.4 and 8.8 m of distance. The contents of the neutral detergent fiber did not vary with distance, while the acid detergent fiber and lignin content varied, but without a clear pattern of response. The crude protein contents reduced quadratically with distance from tree rows and had the highest values under trees (9.8%) and the lowest at 13.5 m of distance (6.5%). The site of pasture, between 7 and 10 m of distance from the tree rows showed the highest benefits of moderate shading on pasture traits.

Soil bulk density and biomass partitioning of Brachiaria decumbens in a silvopastoral system

O sombreamento em sistemas silvipastoris concorre para o conforto termico dos animais; no entanto pode afetar a producao do pasto e contribuir para a compactacao do solo, pelo aumento da concentracao de animais nas areas sombreadas. Avaliou-se o efeito da distância do renque de arvores (sob a copa das arvores, 6 e 12 m de distancia das arvores) na densidade do solo e na biomassa aerea e de raizes de Brachiaria decumbens, nas epocas seca e chuvosa. O estudo foi conduzido num Latossolo Vermelho-Amarelo no delineamento em blocos casualizados, com duas repeticoes. A faixa de arvores foi composta pelas especies Eucalyptus grandis e Acacia mangium, e os piquetes foram manejados com novilhas Holandes (Bos taurus) × Zebu (Bos indicus) , sob lotacao rotativa. A intensidade de sombreamento foi decrescente com o distanciamento do renque de arvores. A densidade do solo nao variou com a distância do renque de arvores, mas sim com a epoca do ano, tendo sido maior na epoca chuvosa (1,47 g dm-3) do que na seca (1,28 g dm-3). As massas secas de forragem verde e de raizes foram menores sob a copa das arvores e maiores na epoca chuvosa do que na seca. Na faixa arborizada houve reducoes de 22,3 e 41,4% na biomassa aerea e de raizes, respectivamente. A maior relacao parte aerea/raiz da B. decumbens a sombra expressa uma modificacao no padrao de alocacao de biomassa na forrageira, que prioriza a formacao da parte aerea, em detrimento do sistema radicular.

Análise econômica de um sistema agrossilvipastoril de área montanhosa na Zona da Mata mineira

The objective of this work was to evaluate the economic viability of an agrosilvipastoral system developed for Zona da Mata mountainous areas in Minas Gerais state, Brazil, as well as to compare different options for wood (Eucalyptus grandis and Acacia mangium) commercialization of the second thinning. The data were obtained from a 10 year-old agrosilvipastoral system established in four hectares at Embrapa Gado de Leite station in Coronel Pacheco, MG, Brazil. As evaluation criteria for the economic viability analysis, the adopted methods were the net present value (NPV) and the internal rate of return (IRR), both calculated at 6% interest rate. Despite the small difference, adding value to forest products increased the attractiveness of the proposed system. Considered separately, the agricultural activity was impracticable, whereas the forestry and livestock activities were independently viable. The studied system seems to be equally tolerant to price variations for forest and livestock products, as well as strongly tolerant to variations in production costs.

Desenvolvimento vegetativo de pinhão-manso em diferentes arranjos de plantio em sistemas agrossilvipastoris

The objective of this work was to evaluate the effect of different planting arrangements on the vegetative growth of physic nut trees established in two agrosilvopastoral intercropping systems. The experiment was carried out in the municipality of Coronel Pacheco, in the state of Minas Gerais, Brazil, in a randomized complete block design, in a split-plot arrangement. The experimental unit was represented by five spacings: 6x3 m (555 plants per hectare), 12x(2x2) m (714 plants per hectare), 10x(2x2) m (833 plants per hectare), 8x(2x2) m (1,000 plants per hectare), and 6x1.5 m (1,111 plants per hectare); and the subplot, by two intercropping systems: agrossilvopastoral (crop-livestock-forestry) and silvopastoral (livestock-forestry). The evaluations were carried out during the 2010/2011 and 2011/2012 harvest seasons. The plant spacing of 6x3 m provided higher crown diameter and number of shoots of physic nut plants in the 2010/2011 harvest season. In the 2011/2012 harvest season, a higher height growth was observed with the 8x(2x2) m plant spacing. The physic nut x corn x forage intercropping system provides higher physic nut plant growth for all studied variables in both harvest seasons.

Florescimento de gramíneas forrageiras cultivadas sob luminosidade reduzida

The influence of reduced light on the flowering of six tropical grass forage was studied. The results showed that shading has affected negativelly the flowering of most species and new researchs are recommended to quantify the seed production and evaluate the physiological seed quality.The influence of reduced light on the flowering of six tropical grass forage was studied. The results showed that shading has affected negativelly the flowering of most species and new researchs are recommended to quantify the seed production and evaluate the physiological seed quality.

Flowering of forage grasses cultivated under reduced light

The influence of reduced light on the flowering of six tropical grass forage was studied. The results showed that shading has affected negativelly the flowering of most species and new researchs are recommended to quantify the seed production and evaluate the physiological seed quality.The influence of reduced light on the flowering of six tropical grass forage was studied. The results showed that shading has affected negativelly the flowering of most species and new researchs are recommended to quantify the seed production and evaluate the physiological seed quality.