Resumo O objetivo do estudo foi avaliar composição química, perfil fermentativo, população de microrganismos e recuperação de matéria seca (RMS) de silagem de cana-de-açúcar contendo níveis crescentes (0, 25, 50 e 75%, na base da matéria natural) de amendoim forrageiro (Arachis pintoi cv. Belmonte), tratadas ou não com Lactobacillus buchneri. Usou-se o esquema fatorial 4×2, no delineamento inteiramente casualizado, com três repetições. Verificou-se efeito de interação níveis de amendoim forrageiro e inoculante para teores de matéria seca, proteína bruta, fibra em detergente neutro e ácido, ácidos orgânicos e etanol, população de bactérias láticas e leveduras, perdas por gases e por efluente e RMS. Houve efeito de níveis de amendoim forrageiro no teor de hemicelulose, nitrogênio insolúvel em detergente ácido, pH e nitrogênio amoniacal. Verificou-se que o aumento de níveis de amendoim forrageiro incrementou teor de proteína e diminuiu teor de fibra, além de reduzir a produção de etanol e de efluente. Recomenda-se inclusão de 40% a 75% de amendoim forrageiro na ensilagem de cana-de-açúcar para melhorar a composição química e o perfil de fermentação. A inoculação com L. buchneri associada ao amendoim forrageiro aumenta a concentração de ácidos antifúngicos na silagem e decresce a população de leveduras e a produção de etanol.

Abstract There is evidence for the beneficial effects of forage peanut on the nutritive value and fermentation profile of silages; however, its effects on sugarcane silage have not been determined. The objective of the study was to evaluate the chemical composition, fermentation profile, microbial composition, and dry matter recovery (DMR) of sugarcane silage containing various amounts of forage peanut (Arachis pintoi cv. Belmonte) (0%, 25%, 50%, and 75% on a fresh matter basis), treated or untreated with Lactobacillus buchneri. A completely randomized 4 × 2 factorial design was used with three replications. The interaction between forage peanut levels and inoculant influenced the concentrations of dry matter, crude protein, neutral detergent fiber and acid detergent fiber, organic acids and ethanol, populations of lactic acid bacteria and yeast, gas and effluent losses, and DMR. Forage peanut levels had effects on dry matter, hemicellulose, acid detergent insoluble nitrogen, pH, and ammonia nitrogen. Increasing proportions of forage peanut increased the protein content and decreased the fiber content in the silage, while also reducing the production of ethanol and effluent. We recommend the inclusion of 40%–75% forage peanut in the sugarcane ensilage to improve the chemical composition and fermentation profile. Furthermore, inoculation with L. buchneri associated with forage peanut increases the concentration of antifungal acids in the silage and decreases the yeast population and ethanol production.

Resumo Avaliou-se a composição bromatológica de silagens de soja sem aditivos (controle), com inoculante microbiano (I), com I + melaço (I+M) e com melaço (M). As plantas de soja foram colhidas no estádio R6 de desenvolvimento e ensiladas em silos laboratoriais de PVC, com capacidade de 2 kg. O inoculante utilizado foi o SIL ALL C4 da Alltech do Brasil associado ou não com 2,5% de melaço, na base da matéria seca. Utilizou-se um esquema fatorial 4 × 6 (4 aditivos × 6 períodos de fermentação) em um delineamento completamente casualizado com 3 repetições. Os períodos de fermentação avaliados foram: 1, 3, 7, 14, 28, e 56 dias. Excluindo os teores de matéria seca e de proteína bruta foi observado efeito (P<0,05) da interação aditivos e período de fermentação sobre as silagens. Observou-se maiores valores médios de matéria seca, de 290,02 g kg-1, e de proteína bruta, de 151,28 g kg-1, para as silagens I+M e M, respectivamente. Foi observado menores valores (P<0,05) de NIDN e de NIDA nas silagens I+M, de 180,47 and 125,07 g kg-1, respectivamente. A adição de inoculante associada ou não ao melaço altera a composição bromatológica de silagens de soja.

Abstract Chemical composition was assessed in soybean silages without any additive (control), with a microbial inoculant (I), with I + molasses (I+M), and with molasses only (M). Soybean plants were harvested at the reproductive 6 (R6) stage and ensiled in 2 kg-capacity PVC laboratory silos. The SIL ALL C4 inoculant produced by Alltech Brazil was used in combination with or without 2.5% molasses added to the natural matter base. A 4 × 6 factorial arrangement (4 additives × 6 fermentation periods) in a completely randomised design with 3 replications was used. The assessed fermentation periods were 1, 3, 7, 14, 28, and 56 days. Excluding the dry matter and crude protein contents it was observed an interaction effect (P<0.05) between the additive and fermentation periods in the silages. It was observed higher average values of dry matter, equal 290.02 g kg-1, and crude protein, equal 151.28 g kg-1, to I+M and M silages, respectively. It was observed lowest values (P<0.05) to neutral detergent insoluble nitrogen (NDIN) and acid detergent insoluble nitrogen (ADIN) contents in I+M silages, equal 180.47 and 125.07 g kg-1, respectively. The addition of inoculant associated or not with molasses improved affect the chemical composition of soybean silages.

Resumo Objetivou-se avaliar as características estruturais, a produção de massa seca e a composição bromatológica de cultivares de Brachiaria e Panicum. O estudo foi conduzido em casa-de-vegetação, em delineamento em blocos casualizados, com cinco tratamentos, sendo três cultivares de Brachiaria (B. decumbens cv. Basilisk, B. brizantha cv. Marandu e cv. Xaraés) e dois cultivares de Panicum (P. maximum cv. Mombaça e cv. Tanzânia), com quatro repetições. De modo geral, maior número de folhas, comprimento laminar e perfilhos foram verificados nas cultivares Mombaça, Tanzânia e Basilisk. As cultivares Tanzânia e Mombaça se destacaram na produção de massa seca, em relação a cv. Marandu, com as outras cultivares com posição intermediária, enquanto a cultivar Xaraés apresentou a maior relação lâmina/colmo. Não houve diferenças nos teores de proteína bruta entre as cultivares, enquanto os teores de fibra em detergente neutro e fibra em detergente ácido foram inferiores para Marandu e Xaraés. Com base nos resultados, todas as cultivares poderiam ser recomendadas, atendendo-se às suas diferentes exigências nutricionais,

Abstract The aim of this study was to evaluate the dry matter production and the structural and bromatological characteristics of Brachiaria and Panicum cultivars. The study was conducted in a greenhouse in a randomized complete block design with five treatments, three cultivars of Brachiaria (B. decumbens cv. Basilisk, B. brizantha cv. Marandu and cv. Xaraes) and two cultivars of Panicum (P. maximum cv. Mombaça and cv. Tanzania), with four replications. Higher number of leaves, greater laminar length and tillers were observed in Mombaça, Tanzania, and Basilisk cultivars. Tanzania and Mombaça cultivars showed higher production of dry mass in relation to Marandu, and Xaraes cultivar showed higher leaf/stem ratio. There was no difference in crude protein content among cultivars, while neutral detergent fiber and acid detergent fiber content was lower for Marandu and Xaraes. We recommend all the cultivars considering their different nutritional requirements.

Objetivou-se avaliar o efeito de melaço e ou aditivo microbiano na ensilagem de soja sobre o consumo, digestibilidade dos nutrientes e desempenho produtivo de bovinos de corte. O delineamento experimental utilizado foi o em blocos casualizados com quatro tratamentos (dietas com silagem de soja (SS), SS com inoculante microbiano, SS com melaço e SS com inoculante microbiano e melaço) e sete repetições. Os animais foram confinados por um período de 99 dias. As dietas continham relação volumoso:concentrado de 70:30, sendo o volumoso 40% de silagem de soja e 30% de silagem de milho. Observou-se menor consumo de nutrientes na dieta contendo SS em relação à dieta SS com inoculante e melaço. Na dieta contendo SS com inoculante e melaço, foram observadas maiores digestibilidades aparentes para MS, PB, FDN, FDA e CNF. A conversão alimentar, o ganho médio diário e o ganho de carcaça não foram influenciados pelas dietas, registrando-se valores médios de 5,90; 1,49 e 0,91 kg dia-1, respectivamente. Conclui-se, que a adição de melaço na presença ou não de inoculante bacteriano à soja por ocasião da ensilagem, não afeta o desempenho de bovinos de corte, embora favoreça o consumo e a digestibilidade de nutrientes.

This experiment evaluated the effect of molasses with or without microbial additive on soybean silage regarding the intake, digestibility and growth performance of beef cattle. The experimental design used was randomized blocks with four treatments (diets with soybean silage (SS), SS with microbial inoculant, SS with molasses and SS with microbial inoculant and molasses) and seven replications. Animal were feedlot fed for 99 days. Diets contained forage: concentrate ratio of 70:30, the forage consisted of 40% soybean silage and 30% corn silage. There was lower intake of nutrients in the diet containing SS in relation to the SS diet added with inoculant and molasses. The diet containing SS with inoculant and molasses presented higher apparent digestibility for DM, CP, NDF, ADF, and NFC. Feed conversion, average daily gain and carcass gain were not influenced by the diets, with mean values of 5.90; 1.49 and 0,91 kg day-1 respectively. The addition of molasses combined or not with bacterial inoculant to soybean at the time of ensiling has no effect on the performance of beef cattle, although favoring the intake and digestibility of nutrients.

Os atributos físicos e a fertilidade do solo são importantes fatores envolvidos na formação e no estabelecimento de pastagens. Mudanças nos atributos físicos interferem na movimentação de água, ar e nutrientes e crescimento de raízes, o que reflete na produtividade e longevidade dos pastos. Assim, objetivou-se avaliar os atributos físicos do solo e a produtividade de massa de matéria seca de um pasto de capim-braquiária cv. Basilisk (Brachiaria decumbens cv. Basilisk), sob doses crescentes de nitrogênio, em um Latossolo Vermelho-Amarelo distrófico. O experimento foi conduzido na Fazenda Rio Manso da Universidade Federal dos Vales do Jequitinhonha e Mucuri/UFVJM, na cidade de Couto de Magalhães de Minas, MG. Para a avaliação da produtividade anual da forrageira, utilizou-se o esquema de parcelas subdivididas no delineamento em blocos casualizados, com quatro repetições, com as doses de nitrogênio (0, 50, 100, 150 e 200 kg/ha/ano) nas parcelas e os anos agrícolas (1º e 2º), dispostos nas subparcelas. Para a avaliação do solo, utilizou-se o esquema de parcelas subdivididas, com as doses de nitrogênio (0, 25, 50, 75 e 100 kg/ha/corte) nas parcelas e os três momentos de amostragem (antes do início do experimento, ao final do 1º ano agrícola e ao final do 2º ano agrícola) nas subparcelas, no delineamento em blocos casualizados, com quatro repetições. Essa análise foi realizada separadamente, para as profundidades de coleta de solo de 0-3 e 10-13 cm. Nas amostras da planta forrageira, foi analisada a produtividade anual de massa de matéria de seca (PMS); nas amostras de solo, foram analisados pressão de pré-consolidação (σp), densidade do solo inicial (DS), volume total de poros (VTP) e índice de vazios (Ie). Concluiu-se que doses mais elevadas de nitrogênio aumentaram a produtividade de matéria seca do pasto de capim-braquíaria, assim como a pressão de pré-consolidação do solo. O volume total de poros e o índice de vazios diminuíram e a densidade do solo inicial aumentou, mas não a ponto de promover a compactação do solo.

The physical properties and fertility of the soil are important factors in the formation and establishment of pasture. Changes in physical properties affect the movement of water, air, nutrients and roots, which, in turn, affect the productivity and longevity of pastures. The objective of this study was to evaluate the physical properties of the soil and the dry matter yield of a pasture with signalgrass cv. Basilisk (Brachiaria decumbens cv. Basilisk), fertilized with increasing nitrogen doses (N), on a dystrophic Red-Yellow Latosol. The experiment was conducted on the Fazenda Rio Manso of the Universidade Federal dos Vales do Jequitinhonha e Mucuri, in Couto de Magalhães de Minas, State of Minas Gerais, Brazil. To evaluate the annual forage yield, a split plot scheme in a randomized block design with four replications was used, with N doses (0, 50, 100, 150, and 200 kg/ha/year) in the plots and growing seasons (first and second) in the subplots. For soil evaluation, a split plot scheme was used with N doses (0, 25, 50, 75 and 100 kg/ha/cut) in the plots and three sampling times (prior to the experiment, at the end of the first growing season and at the end of the second growing season) in the subplots in a randomized block design with four replications. This analysis was performed separately at two soil depths (0-3 and 10-13 cm). Forage samples were analyzed for the annual dry matter yield (DMY), and soil samples were analyzed for pre-consolidation pressure (σp), initial soil bulk density (Bd), total pore volume (TPV) and void index (Vd). Higher nitrogen doses increased the dry matter yield of signalgrass pasture and the pre-consolidation pressure of the soil. The total pore volume and void index decreased, and the initial soil bulk density increased, though without promoting soil compaction.

The objective of this study was to evaluate the fermentation profile, chemical composition and microbial population and losses in the silages of signalgrass and Mombasa grass fertilized with the following levels of nitrogen (N): 0, 30, 60 and 90 kg/ha. The grasses were harvested at 70 days of regrowth, chopped and then ensiled in laboratory silos that had 20 kg of capacity and a snap-top cover and were fitted with Bunsen valves. Before ensiling, samples of the plants were used for the isolation and identification of lactic acid bacteria (LAB) in epiphytic microbiota. The design adopted was a 4 × 2 factorial arrangement, with four doses of N and two forage species, in a completely randomized design, with four replicates. The predominant species of LAB was Lactobacillus fermentum. The interaction between the N dose and forage species affected the dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and water soluble carbohydrates (WSC) of the silages. The pH values and gas losses were influenced only by the forage species, with higher values for the Mombasa grass. For the ammonia (NH3-N) levels and effluent losses, there was an effect of the interaction between the forage species and N doses, and the highest values of NH3-N and effluent losses were found in the Mombasa grass silage fertilized with 60 kg N/ha. Nitrogen fertilization reduces the levels of DM and WSC in the silages and also increases the levels of CP, NH3-N and effluent losses.

The objective of this study was to assess the effect of applying N and K2O at different times after harvest on the structure and production characteristics of Marandu and Xaraés cultivars of Brachiaria brizantha. Two greenhouse 4 × 2 factorial experiments using a randomized block design with eight treatments and four replicates were carried out. In experiment 1, the plants in pots were fertilized weekly with 50 mg/dm³ of N and K2O until a week before a uniformity cut, for a total of four applications. After cutting, plants were fertilized with 50 mg/dm³ of N and K2O at 0, 3, 6, and 9 days. Cultivars were evaluated after 44 days of regrowth. In experiment 2, a single 50 mg/dm³ dose of N and K2O was applied a week before the uniformity cut, and 100 mg/dm³ of N and K2O were applied at 0, 4, 8, and 12 days after cutting; cultivars were evaluated after 39 days of regrowth. In experiment 1, the leaf/stem ratio and dry matter yield were influenced by the time at which fertilizers were applied. In the second experiment, the total number of leaves, expanded leaves, dead leaves, and the leaf lamina accumulated length and dry matter production were influenced by the time at which fertilizers were applied. Marandugrass had more leaves and tillers than cv. Xaraés, which, in turn, had greater height, dry matter yield and regrowth vigor. Applying nitrogen and potassium fertilizer immediately after cutting improves the structural characteristics, while the dry matter yield is maximized by applying fertilizers immediately after cutting by using lower doses of N, or at 4.5 days after cutting by using higher doses of N.

This study was carried out to evaluate the productivity and utilization efficiency of a mixed marandugrass (Brachiaria brizantha cv. Marandu), forage peanut (Arachis pintoi cv. Mandobi) and tropical kudzu (Pueraria phaseoloides) pasture, rotationally stocked at four daily forage allowance levels (6.6, 10.3, 14.3 and 17.9% of live weight), in order to define sward management targets for these mixtures. In each stocking cycle, dry matter (DM) accumulation rates, defoliation intensity (%), grazing depth (%) and grazed horizon (cm) were evaluated. Sward targets were defined according to the sward condition that best conciliated the grass-legume balance and the equilibrium between forage production and utilization. Pastures submitted to higher forage allowance levels showed higher productivity, but were less efficiently utilized. It was not possible to establish sward management targets for marandugrass-tropical kudzu pastures. For marandugrass-forage peanut pastures the best sward state was set with forage allowance of 10.3% of live weight. Under rotational stocking, the following sward targets were suggested for these pastures in the Western Amazon: pre-grazing height of 30-35 cm (June to September) or 45-50 cm (October to May) and post-grazing sward height of 20-25 cm (June to September) or 25-30 cm (October to May).

This study was carried out to evaluate the dynamics of sward condition and botanical composition of a mixed pasture of marandugrass (Brachiaria brizantha cv. Marandu), forage peanut (Arachis pintoi cv. Mandobi) and tropical kudzu (Pueraria phaseoloides), rotationally stocked at four daily forage allowance levels (6.6, 10.3, 14.3 and 17.9% of live weight). Sward condition was characterized in each stocking cycle by measuring pre- and post-grazing sward height, forage mass and percentage of bare ground. Botanical composition (grass, forage peanut, tropical kudzu and weeds) was evaluated before each stocking period. Swards under smaller forage allowances presented lower height, forage mass and ground cover. This condition favored the growth of forage peanut, which constituted 21.1, 15.2, 8.4 and 3.8% of forage mass in the last quarter of the experimental period, from the lowest to the highest forage allowance, respectively. Tropical kudzu was sensitive to all forage allowance levels and its percentage in the botanical composition was strongly reduced along the experimental period, especially during the dry season (July to September). Forage peanut cv. Mandobi and marandugrass form a more balanced mixture when pre-grazing sward height is maintained shorter than 45 cm. Tropical kudzu is intolerant to intensive grazing management systems when associated to marandugrass.

The objective of this study was to evaluate the effect of sugar cane ensilage with different Brix degrees, with or without the addition of 0.5% of calcium oxide (lime) on the chemical composition and fermentation losses of silages. A complete random design in a 9 × 2 factorial arrangement was used. Experimental silos were used, ensilage was done every 15 days with Brix measuring, and they were opened after 30 days of fermentation. As the Brix degree of the ensiled material increased, the contents of dry matter (DM) increased and contents of ash, crude protein (CP) and fibers (neutral and acid detergent fiber corrected for proteins - NDFap and ADFap) reduced. After fermentation, DM content of the silage presented a linear increase with the Brix degree content concentration, positively correlating with content of lime, but the contents of ash, CP, EE and NDFap were linearly reduced with the Brix increase. Content of ADFap suffered linear reduction for the treated silage whereas quadratic behavior was found in the untreated silage. Production of ethanol was presented in a quadratic manner for the silages without lime, and cubically in silages with lime, according to the Brix degree. The treated or untreated silages presented an average pH of 3.98 and 3.50, respectively. Contents of acetic acid and butyric acid were not affected by the lime content and Brix degree. Untreated silages presented reduction of contents of propionic acid as the Brix degree increased. The higher the Brix degree value, the higher the total losses of dry matter in the sugar cane silages with or without treatment. The treatment of the sugar cane with 0.5% calcium oxide on the natural matter basis is effective in reducing the undesired fermentation of the ensilage material.

Dry matter yield and chemical composition of forage grasses harvested from an area degraded by urban solid waste deposits were evaluated. A split-plot scheme in a randomized block design with four replicates was used, with five grasses in the plots and three harvests in the subplots. The mineral content and extraction and heavy metal concentration were evaluated in the second cut, using a randomized block design with five grasses and four replicates. The grasses were Brachiaria decumbens cv. Basilisk, Brachiaria ruziziensis, Brachiaria brizantha cv. Marandu and cv. Xaraés, and Panicum maximum cv. Tanzânia, cut at 42 days of regrowth. The dry matter yield per cut reached 1,480 kg ha-1; the minimum crude protein content was 9.5% and the average neutral detergent fiber content was 62.3%. The dry matter yield of grasses was satisfactory, and may be an alternative for rehabilitating areas degraded by solid waste deposits. The concentration of heavy metals in the plants was below toxicity levels; the chemical composition was appropriate, except for phosphorus. The rehabilitated areas may therefore be used for grazing.

Objetivou-se avaliar os índices de crescimento do capim-tifton 85 adubado com quatro doses de nitrogênio (0, 33, 66, 100, e 133 kg/ha de N) e colhido em três alturas da planta (30, 40 e 50 cm). O delineamento experimental utilizado foi inteiramente casualizado em esquema de parcelas subdivididas com três repetições. As doses de nitrogênio corresponderam às parcelas e as alturas na data de corte, às subparcelas. Para todas as variáveis analisadas, a interação dose de N × altura da planta não foi significativa. A taxa assimilatória líquida e a taxa de crescimento relativo do capim-tifton 85 aumentaram com as doses de nitrogênio. A razão de área foliar (RAF) decresceu linearmente com a altura de corte das plantas, mas aumentou, também de forma linear, com a dose de nitrogênio. De modo linear, a razão de peso foliar decresceu com a altura de corte da planta forrageira e aumentou com a dose de nitrogênio. A área foliar específica do capim-tifton 85 foi influenciada de forma linear e positiva apenas pela adubação nitrogenada. O índice de área foliar (IAF) do capim-tifton 85 aumentou cerca de 0,05 unidade a cada centímetro de incremento na altura de corte das plantas. Houve resposta quadrática da dose de nitrogênio no IAF do capim-tifton 85. O acréscimo na altura do capim-tifton 85 na época do corte reduz a participação de lâmina foliar na forragem. A adubação nitrogenada aumenta a taxa de crescimento do capim-tifton 85, portanto, para assegurar colheita eficiente da forragem, ao aumentar a dose de nitrogênio, é necessário reduzir o intervalo de colheita.

The objective this study was to evaluate the growth rates of Tifton 85 bermudagrass under four nitrogen levels (0, 33, 66, 100, and 133 kg/ha N) and harvested at three plant heights (30, 40 and 50 cm). The experimental design was completely randomized in a split plot scheme with three replications. Nitrogen rates were set in the plots and plants heights in the subplots. For all variables, the interaction N rate × plant height was not significant. The net assimilatory rate and relative growth rate of Tifton 85 increased with increasing N rates. The leaf area ratio (LAR) decreased linearly with plant height at harvesting. In contrast, the LAR increased linearly with N rate. Linearly, the leaf weight ratio decreased with plant height at harvesting, and increased with N rate. The specific leaf area of Tifton 85 bermudagrass was influenced linear and positively only by nitrogen fertilization. The leaf area index (LAI) of Tifton 85 bermudagrass increased by about 0.05 unit for each centimeter increase in plant height at harvesting. There was a quadratic response of N in LAI of Tifton 85 bermudagrass. The increase of bermudagrass height at harvesting season decreases the participation of leaf blade in the forage. The nitrogen increases the growth rate of Tifton 85 bermudagrass. To ensure efficient harvesting of forage, the increase of N rate for Tifton 85 Bermudagrass implies a reduction in the harvest interval.

Avaliaram-se os índices de crescimento do capim Coastcross-1 sob cinco doses de nitrogênio (0, 100, 200, 300 e 400 kg/ha.ano) e duas idades de rebrotação (28 e 42 dias). As doses de nitrogênio foram arranjadas em esquema fatorial 5 × 2, em blocos ao acaso, com três repetições. A adubação nitrogenada foi parcelada em três aplicações, realizadas logo após os cortes. Maiores valores de relação folha/colmo e razão de peso foliar foram obtidos aos 28 dias, em comparação aos 42 dias de rebrotação. Houve redução linear na relação folha/colmo com a adubação nitrogenada (de 1,6 para 1,0 nas doses de 0 e 133 kg/ha.corte de N). Por outro lado, a adubação nitrogenada aumentou linearmente a área foliar específica do capim Coastcross-1 aos 28 dias de rebrotação (de 10,3 a 20,8 m²/kg com o incremento de 0 a 133 kg/ha.corte de N), resultando em elevação da sua razão de área foliar. Na ausência de nitrogênio, a área foliar específica foi maior aos 42 dias (14,3 m²/kg) em relação aos 28 dias de rebrotação (8,6 m²/kg). A idade de rebrotação e a adubação nitrogenada modificam o padrão de acúmulo de forragem e as características do pasto de capim Coastcross-1. Durante a estação de maior crescimento, o pasto de capim Coastcross-1 adubado com maior dose de nitrogênio deve ser manejado com menor idade de rebrotação (28 dias).

The Coastcross-1 growth index in relation to five nitrogen doses (0, 100, 200, 300 and 400 kg/ha.year) and two regrowth ages (28 and 42 days) were evaluated. Nitrogen doses were arranged in a 5 × 2 factorial scheme in a randomized complete block design with three repetitions. Nitrogen fertilization was performed in three applications right after the forage harvesting. Higher values for leaf/stem and leaf weight ratio were observed at 28-d regrowth, in comparison with the 42 days of regrowth. Linear reduction of leaf/stem ratio from 1.6 to 1.0 at 0 and 133 kg N/ha.harvest, respectively was observed. The specific leaf area of bermudagrass at 28-d regrowth resulted in increased leaf area ratio (from 10.3 to 20.8 m²/kg with the increase of 0 to 133 kg N/ha. Harvest). At the absence of N treatment, specific leaf rate was higher at 42-d (14.3 m²/kg) in relation to the 28-d of regrowth (8.6 m²/kg). Regrowth age and nitrogen fertilization modify the pattern of forage accumulation and the characteristics of Coastcross-1 pasture. During the summer, the Coastcross-1 grass pasture fertilized with the highest N-dose should be managed at a younger regrowth age (28-d).

Objetivou-se avaliar características morfogênicas e estruturais do capim-tifton 85 adubado com nitrogênio nas doses de 0, 33, 66, 100 ou 133 kg/ha.ano em três alturas à data de corte (30, 40 ou 50 cm). O delineamento foi inteiramente casualizado em esquema de parcelas subdivididas com três repetições. As doses de nitrogênio (N) corresponderam às parcelas e as alturas ao tempo de corte, às subparcelas. A taxa de aparecimento foliar do capim-tifton 85 foi influenciada de forma negativa pela altura da planta na época do corte e de maneira positiva pela dose de nitrogênio. A taxa de senescência foliar e o número total de folhas por perfilho diminuíram, enquanto a taxa de alongamento foliar aumentou com a adubação nitrogenada. Por outro lado, a taxa de senescência foliar e o número total de folhas por perfilho aumentaram com a altura das plantas na época da colheita. Já o número de folhas vivas por perfilho não foi influenciado pela dose de nitrogênio nem pela altura da planta na época do corte. Para uma mesma altura do capim-tifton 85 na época da colheita, a adubação nitrogenada aumenta o fluxo de tecidos e a frequência de desfolhação. Na condição de desfolhação intermitente, o capim-tifton 85 deve ser colhido com altura de até 30 cm.

The objective of this study was to evaluate the morphogenic and structural characteristics of tifton 85 bermudagrass under different nitrogen doses (0, 33, 66, 100 or 133 kg/ha.year of N) and three different plant heights (30, 40 or 50 cm) at harvesting time. A split plot scheme in a completely randomized design with three replications was used. The nitrogen (N) doses stood for the portions and the haversting heights, for the subportions. The leaf appearance rate of tifton 85 bermudagrass was negatively influenced by plant height at harvesting time, but positively influenced by N dose. Leaf senescence rate and total number of leaves per tiller decreased, whereas leaf elongation rate increased with nitrogen fertilization. On the other hand, leaf senescence rates and total leaf number per tiller increased according to the plant height at harvesting time. Contrarily, the number of green leaf per tiller was not influenced by N dose or plant height at harvesting time. For the same height of 'tifton 85' bermudagrass at harvesting time, nitrogen fertilization increases tissues flux and defoliation frequency. Under intermittent defoliation conditions, 'tifton 85' bermudagrass should be harvested at 30 cm of height.

Avaliaram-se a composição mineral e a produtividade de matéria seca do capim-tifton 85 (Cynodon nlemfüensis x Cynodon dactylon) sob diferentes doses de N e idades de rebrotação. Os tratamentos foram dispostos em esquema de parcelas subdivididas, com as doses de N (0, 100, 200, 300 e 400 kg/ha/ano) nas parcelas e idades de rebrotação (28, 42 e 56 dias) nas subparcelas, no DIC, com três repetições. O rendimento forrageiro variou de 5.751 a 20.466, de 8.138 a 22.852 e de 10.525 a 25.239 kg/ha/ano de MS, em função do aumento das doses de N, em plantas colhidas em intervalos de corte de 28, 42 e 56 dias, respectivamente, com eficiência de resposta de 36,8 kg MS/kg N. Os teores de P foram reduzidos com o aumento das doses de N e da idade da planta, variando de 0,27 a 0,16%. Os teores de K decresceram com o aumento da idade da planta, estimando-se teores máximos de K de 1,25; 1,11; e 0,96%, em plantas colhidas com 28, 42 e 56 dias de rebrotação, respectivamente, adubadas com 55 kg/ha/ corte de N. O teor médio de Ca foi 0,48%. Os teores de Mg aumentaram com o incremento das doses de N e decresceram com o aumento da idade da planta, variando de 0,24 a 0,45%.

The dry matter production and mineral content of Tifton 85 bermudagrass (Cynodon nlemfüensis x Cynodon dactylon) on nitrogen rates (0, 100, 200, 300 and 400 kg/ha) and regrowth ages (28, 42 and 56 days) were evaluated. The experimental design was completely randomized with a split plot feature. The main plots referred to N-rates whereas subplots were regrowth ages. The forage yield ranged from 5.75 to 20.46, from 8.13 to 22.85 and from 10.52 and 25.23 t/ha of DM, in response to rates of 0 to 400 kg N/ha, in plants harvested at 28, 42 and 56 days of regrowth, respectively, with a response efficiency of 36.8 kg DM/kg N. The P contents decreased with N rates and plant age increased ranged from 0.27 to 0.16%. The K contents decreased as plant age increased; the maximum K content of 1.25, 1.11, and 0.96% were recorded for plant harvest with 28, 42 and 56 days of regrowth, respectively, fertilized with 55 kg N/ha/cutting. The average Ca content was 0.48%. The Mg content increased as N rates increased and decreased as plant age increased, with values between 0.24 and 0.45%.