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The objective of this study was to evaluate the spatial variability of structural characteristics of deferred pastures of Brachiaria decumbens cv. Basilisk (signal grass) subjected to associations of sward heights (10, 20, 30, and 40 cm) at the beginning of deferment and grazing periods (1, 28, 56, 85, and 113 days). The experiment was arranged in a split-plot and completely randomized-block design with two replicates. Pastures remained deferred from March to June 2010. From June to the beginning of October 2010, deferred pastures were utilized by steers under continuous grazing and at a fixed initial stocking rate of 3.5 AU ha-1. At the beginning of the deferment, the coefficient of variation (CV) for pasture height was reduced linearly with the pasture height. During the grazing period, in the winter, the CV for pasture height was not influenced by initial pasture height; however, it responded quadratically to the grazing period, with a maximum value of 36.4% at 71 days of the period of utilization. The CV for tiller height was reduced linearly with pasture height at the beginning of deferment but increased linearly along with the grazing period. The initial pasture height did not change the CV of the falling index. However, the latter was quadratically influenced by the grazing period, with a maximum value of 59.5% at 67 days of the utilization period. Signal grass pastures deferred at a lower height have a higher spatial variability of the vegetation. In the grazing period, there are changes in the spatial variability of the vegetation of the deferred signal grass.

Abstract: The objective of this work was to evaluate the morphogenetic, structural, physiological, and productive traits of forage peanut (Arachis pintoi) subjected to different levels of artificial shading in the field. The 'Amarillo MG-100' forage peanut was planted in April 2015, and the evaluations were carried out from May 2017 to April 2018. The treatments were: 0, 30, 45, and 75% of artificial shading. There was no significant effect of shading on the morphogenetic traits of forage peanut. Shading increased final leaf length and canopy height and decreased the leaf area index and number of stolons. Photosynthesis, transpiration rate, stomatal conductance, chlorophyll b, and leaf temperature increased quadratically as a function of shading. There was a linear positive effect on the growing cycle length and a quadratic effect on the production of dry matter mass, with the maximum at 30% shade. Forage peanut harvested at 95% light interception (11-cm height) shows adaptation to shading up to 45%, with increased leaf size, canopy height, photosynthetic rate, stomatal conductance, transpiration rate, and chlorophyll b. In addition, plants at 30% shading show a higher yield than those growing under full sun.

Durante os períodos de outubro a dezembro de 2012 e setembro a dezembro de 2013, avaliou-se o efeito residual da adubação nitrogenada (0, 40, 80 e 120 kg ha-1), aplicadas no início do diferimento de pastos de capim-braquiária, sobre a rebrotação e desempenho de bovinos na primavera. O delineamento experimental foi realizado em blocos completos casualizados com duas e três repetições, respectivamente em 2012 e 2013, em esquema de parcelas subdivididas no tempo (período de pastejo). A densidade populacional de perfilhos vivos apresentou resposta quadrática, em 2012, e linear positiva em 2013. A massa de forragem, em ambos os anos, reduziu com avanço do período de pastejo. A porcentagem de lâmiana foliar viva aumentou linearmente com o avanço do período de pastejo nos dois anos de avaliação. A porcentagem de colmo vivo foi afetada pela adubação nitrogenada e período de pastejo, apenas em 2012, com resposta linear positiva e quadrática, respectivamente. A porcentagem de forragem morta reduziu tanto em 2012 quanto em 2013, com menores valores médios ao final do período de pastejo. Não houve efeito da adubação nitrogenada sobre o peso final, ganho de peso diário e ganho de peso diário por área dos bovinos, em ambos os anos experimentais. A adubação nitrogenada, antes do diferimento, não afeta a rebrotação de pastos de capim-braquiária e nem o desempenho de bovinos na primavera.

Resumo: Foram avaliados os efeitos de doses de suplemento (0, 1, 2 e 3 kg animal-1 dia-1) e períodos de pastejos (1, 28, 59, 89 e 103 dias) sobre a estrutura da Brachiaria decumbens cv. Basilisk e a produção de bovinos em pastagens diferidas. O delineamento foi em blocos casualizados com duas repetições. A altura do pasto e as massas de forragem total e de colmo diminuíram com o período de pastejo. A proteína bruta (8,12%) e a digestibilidade in vitro da matéria orgânica (52,74%) não foram influenciadas pelo período de pastejo. Os teores de fibras em detergente neutro e ácido aumentaram linearmente com o período de pastejo. O ganho médio diário dos bovinos variou de 0,419 a 1,019 kg animal-1 dia-1; a taxa de lotação variou de 2,7 a 3,9 UA ha-1; e o ganho médio por área variou de 2,7 a 7,9 kg ha-1 dia-1, sendo os maiores valores obtidos com a dose mais alta de concentrado. A suplementação com concentrado aumenta a produção de bovinos em pastagens diferidas. Durante a utilização do pasto diferido no inverno há decréscimos na quantidade e na qualidade da forragem, bem como limitação em sua estrutura. Palavras-chave: Brachiaria decumbens; Ecofisiologia; Manejo do pastejo

This study aimed to evaluate the accumulation, structural characteristics, and chemical composition of deferred signal-grass pastures that were subjected to four treatments: without nitrogen fertilization, intercropped with calopo (Calopogonium mucunoides), and fertilized with urea N (50 kg ha−1 and 100 kg ha−1) for 2 years. The design was in randomized blocks, with two blocks and two repetitions of each treatment per block. There were effects of the interaction between treatment and year on green dry mass, forage accumulation, density of vegetative tillers, and crude protein content (simulated grazing). The effects of the treatments on the height, falling index, green dry mass/dead dry mass ratio, number of dead, live and total tillers, and crude protein content (direct cutting) were also observed. Signal-grass–calopo-intercropping ensured adequate mass and forage accumulation and crude protein content equivalent to those of fertilized pastures. In addition, the intercropped pasture showed a higher percentage of leaves and a higher crude protein content compared with those for the other treatments (simulated grazing). The green dry mass/dead dry mass ratio was highest in the intercropped pasture and was equivalent to only that of the pasture fertilized with a low dose of nitrogen. Therefore, signal-grass–calopo-intercropping may be recommended for deferment.

The objective of this study was to evaluate the effects of the weed Solanum sisymbriifolium (sticky nightshade) on the number and characteristics of Urochloa decumbens cv. Basilisk tillers in pasture continuously stocked by cattle. Two sites of the same pasture were evaluated, one site located close (0.5 m) to the main stalk of the weed and the other located at a distance where no weed was growing within a radius of 2.0 m. The number, weight and morphology of the tillers were evaluated in a completely randomized design with three repetitions. At the site distant from the weed, a higher population density of defoliated tillers without apical meristem was observed. The number of basal and aerial tillers was smaller close to the weed plant. This site was also characterized by smaller numbers of vegetative, reproductive, live, dead and total tillers when compared to the site distant from the weed plant. The weight of vegetative and reproductive tillers was higher at the site close to the weed plant. Tillers close to the weed plant exhibited a greater length of the pseudostem and leaf blade, a larger number of live leaves, and fewer grazed leaves compared to distant tillers. The occurrence of S. sisymbriifolium results in spatial variability of vegetation in U. decumbens cv. Basilisk pasture.

Objetivou-se avaliar o desempenho e a resposta econômica de 20 ovinos distribuídos em delineamento em blocos ao acaso e submetidos a um de cinco tratamentos testando a torta de mamona como ingrediente em rações (torta de mamona não tratada, tratada com calcário calcítico, ureia, fosfato monobicálcico e autoclavada). O volumoso foi feno de capim-tifton 85. Foram considerados os preços de mercado de ingredientes das rações, peso corporal (PC) e peso da carcaça, buscando-se determinar condições mínimas para tornar o empreendimento economicamente viável. De posse do custo de cada ração e do consumo de matéria seca, foram analisados indicadores técnicos, zootécnicos e econômicos utilizando-se o programa Excel®. A produção diária (kg PC e kg carcaça) foi maior para ovinos consumindo rações contendo torta de mamona autoclavada e tratada com fosfato monobicálcico, apresentando maior rotatividade do sistema de produção, resultando em maior número de animais terminados anualmente. Esses sistemas de produção obtiveram maior renda bruta. A compra de animais e alimentação foram os itens mais representativos nas despesas de custeio para produção de PC, representando 44,8 e 43,3%/ano em média, respectivamente. Considerando um preço de venda de R$ 4,70/kg PC e R$ 13,40/kg de carcaça, o sistema de produção com torta tratada com fosfato monobicálcico apresentou melhor resposta econômica, com relação benefício/custo de 1,07, valor presente líquido (VPL) de R$ 73.117,34, taxa interna de retorno (TIR) de 54% e custo total de R$ 4,32/kg PC. Por outro lado, o sistema utilizando torta não tratada como ingrediente apresentou relação benefício/custo de 1,00, VPL de 1.772,62, TIR de 8% e custo total de R$ 4,63/kg PC, sem indícios de intoxicação dos animais. Concluiu-se que a torta de mamona tratada com fosfato monobicálcico é promissora para uso em rações de ovinos.

The effects of four supplement doses (0, 1, 2 and 3 kg animal-1 day-1) on pasture characteristics and on cattle production on Brachiaria decumbens cv. Basilisk pastures in continuous stocking with variable stocking rate were assessed. Experimental design comprised completely randomized blocks with two replications. Concentrate supplementation did not influence mass (4141 kg ha-1 of DM) and production rate of forage (97.6 kg ha-1 day-1 of DM), morphological components and nutrition value in hand-plucked forage. Similarly, the number of live (1.607 tillers m-²) and dead (636 tillers m-²) tillers was not affected by concentrate supplementation. There were linear increases in animal performance (from 0.70 to 1.13 kg animal-1 day-1), stocking rate (1.9 to 3.8 animal unit ha-1) and animal production per area (1.8 to 6.2 kg ha-1 body weight) with supplementation doses. Concentrate supplementation does not change the structural characteristics of signal grass pastures managed in continuous stocking at 20 cm high, but increases animal production.

RESUMO Este estudo foi realizado com o objetivo de efetuar o levantamento fitossociológico em um pasto de capim-gordura (Melinis minutiflora P. Beauv), que vinha sendo pastejado por bovinos de corte, há mais de dez anos, sem estratégia de manejo definida. A pesquisa foi desenvolvida no campus da Universidade Federal de Viçosa, em Viçosa, MG. Para avaliação das características fitossociológicas e da massa seca das plantas daninhas e da forrageira, utilizou-se o método do quadrado inventário, aplicando-se um quadrado de 0,25 m2, lançado, ao acaso, 40 vezes, na pastagem, perfazendo uma área amostral de 10 m2. Em toda a área experimental, foram identificadas 31 espécies e 12 famílias botânicas, tendo como destaque as famílias Poaceae, com oito espécies, e Asteraceae, com sete espécies. A forrageira cultivada M. minutiflora P.Beauv, corresponde a 24,26% da produção total de massa seca, entre espécies levantadas na área. Estes resultados indicam estádio avançado de degradação do pasto de capim-gordura, com elevada infestação por plantas daninhas, inclusive espécies consideradas tóxicas, epinescentes e de alta competitividade com as forrageiras, o que o caracteriza como pasto de baixa capacidade de suporte.

The objective of this study was to evaluate the genotypic stability of agronomic traits in hybrids of Panicum maximum. Hybrids originating from the crosses between two sexual parents and cultivars Mombasa and Tanzania were evaluated in an incomplete-block design. Evaluated traits were total dry matter, leaf dry matter, stem dry matter, percentage of leaves, and leaf:stem ratio. These traits were evaluated in six harvests. Overall, higher repeatability was observed for the traits total dry matter and leaf dry matter, especially when harvests 4, 5, and 6, occurring in spring and summer, were evaluated. The leaf dry matter was the trait that provided the greatest repeatability and determination. The repeatability of stem dry matter, percentage of leaves, and leaf:stem ratio had a low magnitude, even when the coefficient was estimated based on the harvests of better stabilization for the other variables. The hybrids achieved genotypic stabilization in the harvests made in the second rainy season. Harvests made in the rainy season provide greater repeatability and determination, and the inclusion of the dry-season harvest is detrimental to the process of selection of low-repeatability traits such as percentage of leaves.

O sucesso de um cultivo consorciado esta relacionado com o conhecimento de todos os fatores que afetam o crescimento e produção das espécies. Objetivou-se neste trabalho avaliar a produção de grãos de milho sob diferentes manejos de plantas daninhas e arranjos de plantio em sistema agrossilvipastoril. O delineamento experimental foi em blocos casualizados, com três repetições. Os tratamentos foram dispostos no esquema de parcelas subdivididas, sendo as parcelas correspondentes aos sistemas de consórcio: eucalipto ou eucalipto junto com acácia consorciada com milho eBrachiaria brizanthacv. 'Marandu' ou B. decumbenscv. 'Basilisk' ou B. brizanthacv. 'Piatã'. Nas subparcelas, alocaram-se os sistemas de manejo de plantas daninhas: atrazine aplicado isoladamente ou mistura em tanque do atrazine com subdose do nicosulfuron. Adicionaram-se duas testemunhas relativas ao milho em monocultivo nos dois sistemas de manejos de plantas daninhas. As espécies florestais foram transplantadas na ocasião da semeadura do milho e das braquiárias, realizada em plantio direto. A aplicação de nicosulfuron em mistura com atrazine promoveu o aumento da altura de plantas e inserção de espigas, sem influenciar na produtividade de grãos de milho. O eucalipto, acácia e as espécies de braquiárias, estabelecidos concomitantemente, não influenciaram na produtividade de milho. A produtividade de grãos de milho é reduzida no sistema agrossilvipastoril em relação ao monocultivo.

This study aimed to evaluate the initial heights (10, 20, and 30 cm) and deferment periods (171, 141, and 109 days in 2010; and 131, 100, and 71 days in 2011) of Urochloa decumbens cv. Basilisk (signal grass). The factors were arranged in split plot, in a randomized complete block design with three replications. Pastures deferred for a short period had lower masses of forage (5,977 and 6,904 kg/ha of DM in 2010 and 2011, respectively). In 2010, pastures deferred for a short period had lower mass of live stem (942 kg/ha of DM), dead leaf blade (785 kg/ha of DM), and dead stem (1282 kg/ha of DM), higher number of vegetative tillers (797 tillers/m²), fewer reproductive tillers (2 tillers/m²), less falling index (1.4), higher mass of live leaf blade (655 kg/ha of DM). The higher pastures had fewer vegetative tillers (495 and 431 tillers/m² in 2010 and 2011, respectively), larger masses of forage (5,285 and 5,942 kg/ha of DM in 2010 and 2011, respectively), dead leaf blade (968 kg kg/ha of DM in 2010) and dead stem (1,902 kg/ha of DM in 2010). Based on the results obtained in the two years, for use in July, the signal grass can be deferred for 71-109 days with an initial height of 20 to 30 cm. The initial height of 10 cm is recommended when a deferral period above 130 days is adopted.Keywords: Brachiaria decumbens; forage mass; sward height; tiller.

Avaliaram-se as alturas iniciais (10, 20 e 30 cm) e os períodos de diferimento (171, 141 e 109 dias em 2010; e 131, 100 e 71 dias em 2011) da Urochloa decumbens cv. Basilisk (capim-braquiária). Os fatores foram arranjados em parcelas subdivididas e em delineamento de blocos completos casualizados, com três repetições. Os pastos diferidos por curto período apresentaram menores massas de forragem (5.977 e 6.904 kg/ha de MS em 2010 e 2011, respectivamente). Em 2010, os pastos diferidos por curto período apresentaram menor massa de colmo vivo (942 kg/ha de MS), de lâmina foliar morta (785 kg/ha de MS) e de colmo morto (1.282 kg/ha de MS), maiores números de perfilhos vegetativos (797 perfilhos/m²) e menores de reprodutivos (2 perfilhos/m²), menor índice de tombamento (1,4) e superior massa de lâmina foliar viva (655 kg/ha de MS). Os pastos mais altos apresentaram menor número de perfilhos vegetativos (495 e 431 perfilhos/m² em 2010 e 2011, respectivamente), maiores massas de forragem (5.285 e 5.942 kg/ha de MS em 2010 e 2011, respectivamente), de lâmina foliar morta (968 kg/ha de MS em 2010) e de colmo morto (1.902 kg/ha de MS em 2010). Com base nos resultados obtidos nos dois anos, para utilização em julho, o capim-braquiária pode ser diferido por 71 a 109 dias, com altura inicial de 20 a 30 cm. A altura inicial de 10 cm é recomendada quando se adota período de diferimento acima de 130 dias.Palavras-chave: estrutura do pasto; massa de forragem; perfilho; Urochloa decumbens.

Em dois experimentos concomitantes, porém distintos, objetivou-se avaliar a morfogênese da Brachiaria decumbens cv. Basilisk em perfilhos com pseudocolmo de dois tamanhos iniciais (5,0 + 0,6 cm ou 12,0 + 0,9 cm), e em perfilhos com graus de desfolhação variáveis (sem desfolhação, 50% de desfolhação e 100% de desfolhação). O capim-braquiária foi manejado em lotação contínua com altura média de 25 cm. A taxa de senescência foliar e a duração de vida da folha foram, respectivamente, 81% e 22% superiores no perfilho com pseudocolmo inicial de 12 cm, quando comparado ao de 5 cm. Os comprimentos do pseudocolmo e da lâmina foliar e os números de folhas expandidas e vivas foram maiores no perfilho com pseudocolmo de 12 cm. Os perfilhos com 100% de desfolhação apresentaram inferiores taxas de alongamento de colmo, aparecimento e alongamento foliar, comprimento de colmo, e números de folhas expandidas, vivas e mortas em relação aos demais perfilhos avaliados. O incremento do tamanho de perfilhos de B. decumbens resulta em maior número de folhas e comprimento de seus órgãos. O crescimento foliar e de colmo da B. decumbens é reduzido com a desfolhação.

The knowledge of interdependence between defoliation patterns and morphogenesis of grasses allows the identification of the effects of feces deposition by cattle on the pasture. Thus, this work was developed to estimate regression equations for morphogenetic characteristics in function of grazing patterns of the same Brachiaria decumbens pasture under influence of feces deposited by cattle. The pasture was managed under continuous stocking with variable stocking rate to maintain the average height of 25 cm. The increases in defoliation frequency (DF) and grazing intensity (GI) reduced linearly the rates of senescence and leaf and stem elongation, but increased linearly the leaf appearance rate. The DF and GI also linearly reduced the number of dead leaves per tiller and the leaf and stem lengths. The forage loss resulted in adverse effects on the morphogenetic and structural characteristics of B. decumbens. The lowest grazing level near the feces increases forage loss on pasture, the size of leafs and stems, senescence and growth of B. decumbens tillers, and reduces leaf appearance.

Este estudo teve como objetivo avaliar o efeito do componente arbóreo no aporte de serapilheira e de nutrientes em dois Sistemas Agrossilvipastoris, sendo o sistema 1: milho (Zea mays) + eucalipto (híbrido Eucalyptus grandis x E. urophylla) + acácia (Acacia mangium) + braquiária (Brachiaria decumbens); e o sistema 2: milho + eucalipto + braquiária, que foram comparados com monocultivo de pasto, em Viçosa, MG. A serapilheira do componente arbóreo e da forrageira foi coletada mensalmente, a partir dos 34 meses após a implantação, no período de outubro de 2010 a setembro de 2011, em distâncias a partir das linhas centrais do plantio das árvores, que consistiram nos subtratamentos: 1, 3 e 6 m; e realizadas a análise e quantificação de nutrientes: N, P, K, Ca, Mg e S. A deposição da serapilheira da forrageira foi superior no monocultivo de pasto. Entretanto, a maior deposição de serapilheira total (forrageira + componente arbóreo) foi observada em ambos os sistemas agrossilvipastoris, comprovando a influência positiva do componente arbóreo no incremento de material vegetal depositado sobre o solo. A distância da linha de plantio das árvores também influenciou a deposição, que foi maior a 1 m, seguida das distâncias 3 e 6 m. Com exceção do P, os sistemas agrossilvipastoris depositaram maior quantidade de nutrientes por meio da serapilheira, destacando-se o sistema com acácia, que promoveu maior deposição de N. O componente arbóreo, a espécie leguminosa e a distância da linha de plantio das árvores dos sistemas agrossilvipastoris influenciaram a deposição de serapilheira e de nutrientes no solo, indicando a potencialidade desses sistemas para recuperação e manutenção de pastagens degradadas.

The objective of this study was to evaluate grazing management strategies of Brachiaria decumbens cv. Basilisk managed with different heights under continuous grazing with cattle. Two grazing management strategies were evaluated: maintenance of pasture with an average height of 25 cm throughout the experimental period and maintenance of pasture on the average of 15 cm in height during winter, up to 25 cm from the beginning of spring. The split-plot scheme and the randomized block design with four replications were adopted. The grazing management strategies corresponded to the primary factor, while the seasons (winter, spring and summer) corresponded to secondary factor. The reduction of the average sward height to 15 cm in the winter resulted, when compared with pasture maintained at 25 cm, in overall higher growth rates (95 kg/ha.day DM) and leaf blade (66.1 kg/ha.day DM), as well as higher rates of total accumulation (81.5 kg/ha.day DM) and leaf blade (52.6 kg/ha.day DM). The accumulated forage production (from winter to summer) was higher in the pasture lowered to 15 cm in winter (25.6 t/ha DM) compared with that managed with an average height of 25 cm (22.2 t/ha DM). Regarding the seasons of the year, in the winter, there were lower rates of overall growth (6.4 kg/ha.day DM), leaf blade (5.6 kg/ha.day DM) and pseudostem (0.8 kg/ha.day DM), and also lower total (-6.6 kg/ha.day DM) and leaf blade (-7.5 kg/ha.day DM) accumulation rates. In the spring there was a higher rate of leaf senescence (22.4 kg/ha.day DM). The accumulation of forage is incremented when the pasture of B. decumbens is lowered to 15 cm during the winter, and in the spring and summer, its average height is increased to 25 cm.

This study was carried out with the objective of estimating the genetic parameters of agronomic traits in Panicum maximum hybrids. Genotypes obtained from the crosses between the sexual plants S10 and S12 and cultivars Tanzania and Mombasa were evaluated. The design was an incomplete blocks design with two replicates (clones) and 33 blocks. Each block was constituted by three lines or plots with nine plants each, which were evaluated in six harvests. All the characters presented low broad sense heritabilities for both the individual harvest and for the mean of harvests and a large difference between the heritability and the individual repeatability coefficient, which may be due to the high permanent environmental variance, mainly for forage dry matter and leaf dry matter. On the other hand, the percentage of leaves also presented low repeatability and permanent environmental variance. The genotypic coefficients of variation were high, except for leaf percentage, but they were also associated with high residual coefficients of variation. Both the broad sense heritabilities per harvest and for the mean of harvests were of moderate magnitude for the agronomic traits evaluated in hybrid individuals of P. maximum. On the other hand, there is variability for selection of important characters such as total and leaf dry matter yields and selection for leaf percentage needs a greater number of harvests to improve selection efficiency. The genotypes presented great variability for Bipolaris maydis leaf spot incidence and this character can be included in the P. maximum breeding program.

This study evaluated the influence of nitrogen levels (N) and plant density (D) on the tillering dynamics of Tanzania guinea grass (Panicum maximum Jacq.). Treatments were arranged in a completely randomized block design with 12 treatments and two replicates in a factorial scheme (4 × 3) with four levels of N (0, 80, 160 or 320 kg ha-1 N) and three plant densities (9, 25, and 49 plant m-²). Higher number of tillers was observed in the treatment with 9 plants m-² and under higher levels of N, especially in the second and third generations. Still, the N influenced quadratically the appearance rate of basal and total tillers, which were also affected by plant density and interaction N × D. However, the appearance rate of aerial tiller was not influenced by factors evaluated. The mortality rate of total tiller was influenced quadratically by the nitrogen levels and plant densities. The mortality rate of basal tiller responded quadratically to plant density, whereas the mortality rate of aerial tiller increased linearly with fertilization. Pastures with low or intermediate densities fertilized with nitrogen, presented a more intense pattern of tiller renewal.

This study evaluated the influence of nitrogen levels (N) and plant density (D) on the tillering dynamics of Tanzania guinea grass (Panicum maximum Jacq.). Treatments were arranged in a completely randomized block design with 12 treatments and two replicates in a factorial scheme (4 × 3) with four levels of N (0, 80, 160 or 320 kg ha-1 N) and three plant densities (9, 25, and 49 plant m-²). Higher number of tillers was observed in the treatment with 9 plants m-² and under higher levels of N, especially in the second and third generations. Still, the N influenced quadratically the appearance rate of basal and total tillers, which were also affected by plant density and interaction N × D. However, the appearance rate of aerial tiller was not influenced by factors evaluated. The mortality rate of total tiller was influenced quadratically by the nitrogen levels and plant densities. The mortality rate of basal tiller responded quadratically to plant density, whereas the mortality rate of aerial tiller increased linearly with fertilization. Pastures with low or intermediate densities fertilized with nitrogen, presented a more intense pattern of tiller renewal. Objetivou-se com este trabalho avaliar o efeito de doses de nitrogênio (N) e densidades de plantas (D) sobre a dinâmica de perfilhamento do capim-tanzânia (Panicum maximum Jacq.). O delineamento foi em blocos casualizados, com 12 tratamentos e duas repetições em esquema fatorial 4 × 3, com quatro doses de N (0, 80, 160 ou 320 kg ha-1 ano-1) e três densidades de plantas (9, 25 ou 49 plantas m-²). O número de perfilhos foi maior na densidade de 9 plantas m-² e nas maiores doses de N, principalmente na segunda e terceira gerações. O N influenciou quadraticamente as taxas de aparecimento de perfilhos basilares e totais, que também foram influenciadas pela densidade de plantas e pela interação N × D. A taxa de aparecimento de perfilhos aéreos, no entanto, não foi influenciada pelos fatores avaliados. A taxa de mortalidade de perfilhos totais foi influenciada de forma quadrática pelas doses de N e pelas densidades de plantas. A taxa de mortalidade de perfilhos basilares respondeu quadraticamente à densidade de plantas, enquanto a taxa de mortalidade de perfilhos aéreos aumentou de linearmente com a adubação. Pastos implantados em densidades baixas ou intermediárias adubados com nitrogênio apresentam padrão mais intenso de renovação de perfilhos.

The objective of this experiment was to evaluate the genetic divergence between hybrids obtained from 10 sexual genitors of the Panicum maximum breeding program at Embrapa Beef Cattle. For this, the following morphological descriptors were used: plant height, growth habit, leaf aspect, leaf waxiness, hair density on the sheath (DePB) and blade (DePL), degree of hardiness of the hairs on the leaf sheath (DuPB) and blade (DuPL) and length of hairs on the sheath and blade. The characteristics growth habit and waxiness were not included in the analysis for being invariant. The phenotypic correlations were low and, therefore, not used to eliminate variables. By the principal component analysis, an 84.3% accumulation of the variation was observed until the fourth component. The last four principal components presented an estimate lower than 0.7 and allowed the identification of the variables DePB, DuPB and DuPL as the least important for diversity studies. The morphological characters used were not efficient to distinguish the progenies, but allowed the formation of morphological groups that converged with the graphic analysis of the principal components. An apparent error rate of 17.04% was observed in the classification of the individuals in the groups and 55.5% in the classification of the individuals in the progenies. The individuals in the P. maximum half-sib progenies are genetically divergent, but may not be grouped with only the descriptors used in this experiment. The pubescence characteristics were the least important in the discrimination of the genotypes.

This study was conducted to evaluate the daily production of forage and its morphological components, as well as the potential of forage utilization in pastures of Pennisetum purpureum cv. Napier managed with three post-grazing heights (30, 50 and 70 cm). Two experiments were carried out: one from February to May 2009 and another from December 2009 to May 2010, characterizing months of summer and fall. The experimental design was of completely randomized blocks with three replicates. The grazing was performed by crossbred heifers of approximately 270 kg body weight, when the sward intercepted 95% of the incoming light. In both experiments, the pastures managed with post-grazing height of 30 cm, in the summer months (December to March), presented lower daily production of leaves and stems, as well as less daily leaf senescence, which resulted in lower daily forage production and accumulation in comparison with those managed at 70 and 50 cm. In the period from February to March 2009 (experiment 1) and December 2009 to March 2010 (experiment 2), pastures presented greater daily production of leaves and forage, greater daily forage accumulation and more daily leaf senescence in relation to the months of April and May 2009 and 2010. On the other hand, the daily production of stems was higher in the fall, in comparison with the summer. Therefore, elevation in the post-grazing height, especially in the summer, increases the regrowth vigor of elephant grass cv. Napier.

The objective of this study was to evaluate the effect of different levels of nitrogen supply and plants densities in the productivity of mombasa guineagrass (Panicum maximum) in the period of establishment. The design was of completely randomized blocks, with 12 treatments and three repetitions, with four nitrogen supplies (absence of application, 80, 160 and 320 kg/ha.year) and three plant densities (9, 25 and 49 plants/m²). The plot was cut at 30 cm from the ground when the sward high intercepted 95% of light. The following items were evaluated: sward height at 95% light interception, interval and number of cuts, dry mass production, total dry mass of leaves, stems and dead material and the morphologic composition. Nitrogen increased the dry mass production and the dry mass of stem in winter and summer, and decreased in the fall. The total dry mass of leaf presented decrease of 19% in the summer between the smallest and biggest densities in the 320 kg/ha. The dry mass of dead material had negative effect of the density in the fall. The leaf percentage increased 88% between the smallest and largest nitrogen level at the plant density of 49 plants/m². Only density influenced the sward height in the condition of 95% of light interception. The number of cuts increased with nitrogen levels in the fall, spring and summer, while the interval of cuts decreased with fertilization in the spring and summer. Nitrogen increases the production of mombasa guineagrass in each cycle.

This study was conducted to evaluate the defoliation patterns on B. decumbens cv. Basilisk (signalgrass) tiller as a function of influence of feces deposited naturally by cattle. The signalgrass was managed with an average height of 25 cm, under continuous stocking and variable stocking rate. Interval and intensity of defoliation, grazing efficiency and forage loss were evaluated in two sites on pasture - one close and the other distant from feces. The completely randomized block design with three replications was adopted. The defoliation rate of the pasture site close to feces was 40% lower than at that distant from feces. This response pattern was similar to defoliation intensity of leaf blade. The leaf blade of the tiller close to feces also achieved lower de foliation (1.64) than that in the tiller distant from feces (3.97). The relative number of grazed leaf per tiller in the tillers distant from feces was approximately 185% higher than those close to feces. The grazing efficiency was lower in the local close to feces compared with that distant, unlike forage loss. The natural deposition of feces by cattle modifies the grazing and use patterns of B. decumbens under continuous stocking.

The objective of this experiment was to evaluate the nitrogen and plant density influence on the yield, forage dissection and nutritive value of Tanzania grass (Panicum maximum Jacq.). The design was of completely randomized blocks with three replications in a factorial arrangement with four nitrogen levels (0, 80, 160 or 320 kg/ha N) and three plant densities (9, 25 or 49 plants/m²). The plots were cut at 25 cm from soil level when the canopy reached 95% of light interception. The total dry matter forage yield and dry matter forage yield per harvest increased linearly with the nitrogen fertilization. The leaf and stem yield had the same response. The senesced forage yield was quadratically influenced by the nitrogen. The stems ratio in the morphologic composition was high in the high nitrogen levels and in the low plant densities. The leaf:stem ratio showed high values in this trial, but it was increased in plots without nitrogen and high plant density. The pre-grazing height was reduced with the increase in plant density. The nutritive value was favored by the nitrogen fertilization, which increased the crude protein level and reduced neutral detergent fiber and lignin. These factors increased the leaf and stem in vitro digestibility of organic matter. Nitrogen fertilization increases the forage yield of Tanzania grass under rotational grazing. After the establishment, plant density has little influence on the Tanzania grass yield and its forage dissection. The harvest with 95% light interception improves the structure and nutritive value of Tanzania grass pastures.

The analysis of both morphogenetic and structural characteristics of pasture allows us to understand the response patterns of the plant to the environment. Thus, this study was conducted to evaluate the associations between the morphogenetic and structural characteristics of Brachiaria decumbens under continuous grazing by cattle. The development of individual tillers in pastures was evaluated under two grazing management strategies during three seasons (winter, spring and summer). Pearson correlations between variables were estimated. The lengths of leaf and stem, number of tillers and leaves per tiller, rates of leaf appearance and elongation of leaf and stem of B. decumbens were positively correlated. There was a negative relationship between appearance and lifespan of leaves (r = -0.89). However, positive correlations between leaf appearance rate and number of tillers (r = 0.64) and between length of stem and leaf senescence rate (r = 0.63) were determined. The B. decumbens modifies its morphogenesis to better adapt to climate and grazing management.

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 with the aim of assessing the efficacy of the fluazifop-p-butyl herbicide to control Brachiaria brizantha, cultivar Marandu, in the formation of Tifton 85 grazing. Treatments consisted of five doses of fluazifop-p-butyl herbicide (0.0, 62.5, 125.0, 187.5 and 250.0 g ha-1) plus controls with no herbicide, in a completely randomized layout, with four replications. Each plot consisted of a 10-L capacity pot, with two B. brizantha plants and two Tifton 85 plants. The herbicide application was conducted before the tillage of B. brizantha, when they were about 15 cm high. Visual assessments of control of B. brizantha and intoxication of Tifton 85 plants, at 07, 21 and 45 days after application were carried out. Sixty days after application, plants were harvested at ground level and oven-dried. Regrowth was assessed in the same manner, 60 days after cutting, to determine their dry weight. Control of B. brizantha was noted to be above 50%, from doses of 218.75 g ha-1 at 45 days after application. The fluazifop-p-butylherbicide did not show to be efficient in the control of B. brizantha in the doses assessed and caused intoxication to Tifton 85 plants.

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.

Objetivou-se com este trabalho avaliar o efeito da adubação nitrogenada e da densidade de plantas nas características morfogênicas e estruturais do capim-mombaça (Panicum maximum Jacq. cv mombaça). O experimento foi realizado em delineamento de blocos casualizados, com 12 tratamentos e três repetições, com quatro doses de nitrogênio (0, 80, 160 e 320 kg/ha.ano) e em três densidades (9, 25 e 49 plantas/m²) nas quatro estações do ano. O corte foi realizado a 30 cm do nível do solo, quando o dossel atingia 95% de interceptação luminosa. Foram mensuradas as taxas de aparecimento foliar, senescência e alongamento foliar, filocrono, taxa de alongamento de pseudocolmo, número de folhas vivas, duração de vida das folhas, número de perfilhos totais por touceira e taxas de aparecimento e mortalidade dos perfilhos totais. A adubação nitrogenada influenciou positivamente as taxas de aparecimento foliar e de perfilhos totais (outono e inverno), as taxas de alongamento foliar (primavera e verão) e de pseudocolmos (verão), a taxa de senescência foliar (outono, inverno, primavera e verão) e o número de folhas vivas e de perfilhos totais (primavera e verão). A adubação também influenciou positivamente o perfilhamento do capim-mombaça. As densidades mais elevadas aumentaram as taxas de alongamento e senscência foliar e diminuíram o número de perfilhos. A adubação nitrogenada reduz o filocrono e a duração de vida das folhas (primavera e verão), mas não influencia a taxa de mortalidade de perfilhos.The objective of this experiment was to evaluate the effect of the nitrogen fertilization and density of plants in the morphogenic and structural characteristics of mombaça grass (Panicum maximum Jacq.). The experiment was set up as a completely randomized block design with 12 treatments and three repetitions, with four applications of nitrogen (0, 80, 160 and 320 kg/ha.year) and three densities (9, 25 and 49 plants/m²) in the four seasons of the year. The plot was cut at 30 cm from the ground, when the light interception reached 95%. The following measures were done: leaf appearance and elongation rate, Phyllochron, leaf senescence rate, number of live leaves, leaf lifetime, stem elongation rate and rates of appearance and mortality of the total tiller. Nitrogen fertilization positively influenced the leaf and tiller appearance (fall and winter) rates, leaf elongation (spring and summer), and stem elongation (summer) rates, leaf senescence (all the stations) rate and number of live leaves and tillers (spring and summer). The fertilization also influenced positively the tillering of mombaça grass. Higher densities of plants increased the elongation and leaf senescence rates and decreased the number of tillers. Nitrogen fertilization reduces the phyllocron and life lenght of leaves (spring and summer), but does not affect the mortality rate of tillers.

Este trabalho foi realizado com o objetivo de identificar estratégias eficazes de manejo do pastejo de Brachiaria decumbens cv. Basilisk, sob lotação contínua, com base em avaliações das suas características morfogênicas e estruturais. Duas estratégias de manejo do pastejo foram estudadas: em uma, o pasto foi mantido com 25 cm de altura média durante todo o período experimental e, na outra, foi mantido em 15 cm de altura média durante o inverno, com aumento para 25 cm a partir do início da primavera. Adotou-se o delineamento de blocos casualizados em esquema de parcelas subdivididas com quatro repetições. Consideraram-se, como fator primário, as estratégias de manejo do pastejo, caracterizadas pelas alturas médias dos pastos durante as estações do ano (inverno, primavera e verão), e, como fator secundário, as estações. O rebaixamento do pasto para 15 cm no inverno resultou em maior taxa de aparecimento foliar (0,02 folha/perfilho.dia) e maior número de folhas vivas (4,5 folhas por perfilho) no inverno, mas provocou redução, no inverno, da duração de vida da folha (66 dias), da taxa de senescência foliar (0,22 cm/perfilho.dia) e dos comprimentos da lâmina foliar (11 cm) e pseudocolmo (15,2 cm) em relação ao pasto com 25 cm. Nesta estação, foram menores os valores observados para as taxas de aparecimento foliar (0,06 folha/perfilho.dia), alongamento foliar (0,110 cm/perfilho.dia) e alongamento de pseudocolmo (0,008 cm/perfilho.dia), número de folha viva (2,9 folhas por perfilho) e comprimentos da lâmina foliar (8,6 cm) e do pseudocolmo (13,5 cm). Por outro lado, a duração de vida da folha (139 dias) e o número de folhas mortas (2,0 folhas por perfilho) foram maiores. O maior valor de taxa de senescência foliar ocorreu na primavera (0,40 cm/perfilho.dia). O pasto de B. decumbens cv. Basilisk sob lotação contínua pode ser manejado de forma sazonal, com rebaixamento para 15 cm no início do inverno e posterior aumento para 25 cm no início da primavera.This study was conducted to identify effective strategies for grazing managing of Brachiaria decumbens cv. Basilisk, under continuous stocking, based on assessments of their morphogenetic and structural characteristics. Two strategies of grazing management were studied: in one, the grass was maintained with 25-cm mean height throughout the experimental period, and in the other, it was 15 cm during the winter, rising to 25 cm from the beginning of spring. The split-plot in randomized block design with four replications was adopted. The strategies of grazing management responded to primary factor, characterized by average heights of pastures during the seasons (winter, spring and summer). The seasons corresponded to secondary factor and consisted of measures over the experimental period. Pasture's lowering to 15 cm in the winter resulted in higher leaf appearance rate (0.02 leaves/tiller.day) and higher number of live leaves (4.5 leaves/tiller) in the winter. However, this management strategy lowered leaf lifespan (66 days), leaf senescence rate (0.22 cm/tiller.day), and length of leaf lamina (11 cm) and stem (15.2 cm) in winter months, in relation to pasture with 25 cm. During this season, rates of leaf appearance (0.06 leaves/tiller.day), leaf elongation (0.110 cm/tiller.day) stem elongation (0.008 cm/tiller.day), live leaves (2.9 leaves/tiller), length of leaf lamina (8.6 cm) and stem (13.5 cm) lowered. On the other hand, leaf lifespan (139 days) and number of dead leaves (2.0 leaves/tiller) were higher. The highest leaf senescence rate occurred in the spring (0.40 cm/tiller.day). The B. decumbens cv. Basilisk pasture under continuous stocking can be managed on a seasonal basis, with decrease to 15 cm in early winter, and further increase to 25 cm in early spring.

Objetivou-se estabelecer estratégias de manejo do pastejo, sob lotação contínua, que otimizem o padrão natural de perfilhamento da Brachiaria decumbens cv. Basilisk. Duas estratégias de manejo do pastejo foram estudadas: em uma, o pasto foi mantido com 25 cm de altura média durante todo o período experimental; e na outra foi mantido em 15 cm de altura média durante o inverno, com aumento para 25 cm a partir do início da primavera. Adotou-se o esquema de parcelas subdivididas em delineamento em blocos casualizados com quatro repetições. Consideraram-se como fator primário as estratégias de manejo do pastejo, caracterizadas pelas alturas médias em que os pastos foram mantidos durante as estações do ano (inverno, primavera e verão) e, como fator secundário, as medidas ao longo do período experimental. A taxa de aparecimento de perfilho (4,7%), a taxa de mortalidade (4,7%) e o índice de estabilidade (0,998) foram menores no inverno. Nesta estação, contudo, a taxa de sobrevivência de perfilho foi maior (95,3%). Em comparação aos pastos mantidos com 25 cm, aqueles manejados com 15 cm de altura média no inverno apresentaram maiores taxas de aparecimento de perfilho (34,2%) e índice de estabilidade (1,065). O florescimento do capim-braquiária ocorreu apenas no verão e com pouca intensidade (0,5%). A otimização da renovação de perfilhos no pasto de B. decumbens cv. Basilisk sob lotação contínua ocorre com seu rebaixamento para 15 cm no início do inverno e seu posterior aumento para 25 cm no início da primavera.The experiment was conducted to establish management strategies of grazing under continuous stocking that optimize the natural pattern of tillering of Brachiaria decumbens cv. Basilisk. Two strategies of grazing management were studied: in one, the grass was maintained with 25-cm mean height throughout the experimental period, and in the other, 15-cm mean height during the winter, rising to 25 cm from beginning of spring. The split-plot in randomized block design with four replications was adopted. The strategies of grazing management corresponded to primary factor, characterized by average heights of pastures during the seasons of the year (winter, spring and summer). The seasons corresponded to secondary factor and consisted of measures over experimental period. The rates of tillers appearance (4.7%), death (4.7%) and stability index (0.998) were lower in winter. During this season, however, the tiller survival rate was higher (95.3%). Compared with pastures maintained at 25 cm, those managed with 15 cm in winter had higher tiller appearance rate (34.2%) and stability index (1.065). The signalgrass flowering occurred only in the summer and with low intensity (0.5%). Optimization for renewal of tillers in B. decumbens cv. Basilisk pasture under continuous stocking occurs with its decrease to 15 cm at the beginning of winter and subsequent increase to 25 cm in early spring.

O experimento foi conduzido com os objetivos de avaliar a altura do dossel com 95% de interceptação luminosa e quantificar a influência da adubação nitrogenada e da densidade de plantas nas características morfogênicas e estruturais de capim-tanzânia. Quatro doses de nitrogênio, N (0, 80, 160 e 320 kg.ha-1), foram combinadas com três densidades de plantas (9, 25 e 49 plantas.m-2), em um arranjo fatorial 4 × 3, em delineamento inteiramente casualizado com três repetições, para avaliação da produção de biomassa, e duas repetições, para avaliação das características morfogênicas e estruturais. O acúmulo de MS total durante o período experimental foi influenciado pela adubação nitrogenada e pela densidade de plantas. No período das águas, as maiores doses de nitrogênio diminuíram o intervalo de colheitas e, consequentemente, aumentaram o número de colheitas. A altura do dossel de capim-tanzânia com 95% de IL foi positivamente influenciada pela densidade de plantas nos períodos das águas e de transição água-seca e seca. A altura do capim-tanzânia com 95% de IL apresentou variações ao longo das avaliações, de modo que os valores foram maiores (próximos a 70 cm) no período das águas, seguido pelos períodos de transição água-seca e seca.This experiment was carried out to evaluate canopy height of guinea grass with 95% of photosynthetic active radiation interception and quantify the nitrogen fertilization influence and plants' density on the morphogenesis and structural characteristics of Tanzania grass. Four doses of N (0, 80, 160 e 320 kg.ha-1), were arranged with three plant densities (9, 25 and 49 plants.m-2), according to 4 × 3 completely randomized design, with three repetitions. Total dry matter (DM) accumulation throughout the experimental period was influenced by nitrogen fertilization and plants' density. In the rainy period, the higher nitrogen fertilization decreased the harvesting intervals, and consequently, increased the number of harvests. The rate of leaf appearance and the phyllochron were influenced only under nitrogen fertilization in the transition period of rainy and dry weather. Tanzania grass canopy height under 95% of light interception was positively influenced because of the plant densities in rainy period and transition period between rainy/drought and drought. Tanzania grass height under 95% of light interception presented variations along the evaluations and the values were higher (near 70 cm) in the rainy period, followed by transition period rain/drought and drought.

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.

The objective of this work was to evaluate effects of nitrogen fertilization and plant density on morphogenesis of Tanzania guinea grass. It was used a random block design with 12 treatments and two replications in a 4 × 3 factorial arrangement, with four doses of nitrogen (N) (without N application, 80, 160 or 320 kg/ha.year) and three plant densities (9, 25 or 49 plants/m²). Harvest was performed at 25 cm from the ground when the canopy intercepted 95% of the incident light. Rates of leaf appearance and pseudostem elongation were positively and linearly influenced by nitrogen, whereas phillochron and leaf life span were influenced linearly and negatively. Leaf elongation responded positively to two factors, whereas leaf senescence rate and number of live leaves were not influenced by the factors evaluated. Number of total, basal and aerial tillers were greater at the density of 9 plants/m² and at the nitrogen dose of 320 kg/ha.year. Nitrogen increases production of leaves and tillers in Tanzania guinea grass defoliated at 95% of light interception, but high density of plants reduces the number of tiller per bunch.

O objetivo foi avaliar as características estruturais da Brachiaria decumbens cv. Basilisk em relação à planta daninha Solanum sisymbrifolium no pasto. Os tratamentos foram dois locais no mesmo pasto, quais sejam, próximo e distante da planta daninha. O delineamento foi em blocos ao acaso com três repetições. O pasto foi manejado sob lotação contínua, com bovinos e com altura média de aproximadamente 25 cm. Foram quantificadas as densidades populacionais das categorias de tamanho dos perfilhos, a altura, a interceptação de luz, as massas e as densidades volumétricas dos componentes morfológicos do pasto. No local distante da planta daninha houve maior ocorrência de perfilhos com tamanho inferior a 20 cm. Já no local próximo da planta daninha, predominaram perfilhos com tamanho superior a 40 cm. A presença da planta daninha ocasionou aumento na altura do pasto e incremento na interceptação de luz pelo dossel. As massas e as densidades volumétricas de lâmina foliar viva, colmo vivo e material morto foram inferiores no local próximo da planta daninha em relação ao local distante. A ocorrência da planta S. sisymbrifolium provoca variabilidade espacial da vegetação no pasto de B. decumbens manejado sob lotação contínua com bovinos.The objective of this study was to evaluate the structural characteristics of Brachiaria decumbens cv. Basilisk in relation toSolanum sisymbrifolium in pasture. The treatments were two sites in the same pasture, near and far from the weeds. A randomized block design with three replications was used. The pasture was managed under continuous stocking and grass height was kept at about 25cm.Densities were quantified for categories tiller size, height, light interception, masses and volumetric densities of morphological components of the pasture. In the site far from the weeds there is a higher occurrence of tillers with size smaller than 20 cm. In site near the weeds, tillers larger than 40 cm prevailed. The presence of weeds caused an increase in sward height and light interception by the canopy. The masses and volumetric densities of living leaf, stem, living and dead material were lower in the site near the weeds in relation to the remote site. The occurrence of S. sisymbrifolium causes spatial variability of vegetation in B. decumbens pasture.

The objective of this study was to evaluate the number oftillers with different levels of defoliation and theircharacteristics on the Brachiaria decumbens cv. Basilisk pasture. Three different areas on the pasture (undergrazed, with proper grazing and overgrazed) and three tiller categories (without defoliation, withdefoliation and without shoot apical meristem) were evaluated. Randomized block design with three repetitions was used. The B. decumbens pasture was managed under the continuous stocking system with cattle, and the grass height was kept at about 25cm. Thenumber of tillers showing defoliation was higher (1,333 tillers/m²) for the overgrazed area compared to the area with proper grazing and the undergrazed area. Inverse response pattern was observed for the tillers without defoliation. On the other hand, the number of tillerswithout the shoot apical meristem was higher in the areas with proper grazing (395 tillers/m²). Tillers without defoliation showed a lower pseudoculm length (10.3cm)and a smaller number of dead leaves (0.22) when compared to the other categories. The length of the leafblade did not change for the tiller categories evaluated. The number of grazed leaves was lower for tillers without the shoot apical meristem in relation to the ones showing or not defoliation. Lower leaf area for the tillers that had the shoot apical meristem removed was observed. Tillers without the shoot apical meristem showed a lowerpercentage of green leaf blade (GLB), higher percentages of both live culm (LC) and dead leaf blade (DLB) as well as a lower relation of the GLB/LC and weight comparing to the tillers showing or not defoliation. Those last ones did not differ regarding their morphological composition. There is indeed spatial variability of the vegetation andtiller diversity with varying levels of defoliation on Brachiaria decumbens cv. Basilisk pastures under continuous grazing.

Objetivou-se estudar a relação entre o número e o peso de categorias de perfilhos em pasto de Brachiaria decumbens cv. Basilisk sob lotação contínua com bovinos. O pasto foi manejado com altura média de aproximadamente 25 cm. Foram avaliadas quatro alturas de plantas no mesmo pasto (10, 20, 30 e 40 cm), em delineamento de blocos ao acaso, com duas repetições. Os números de perfilhos vegetativos, vivos e totais reduziram linearmente com a altura da planta. O número de perfilho reprodutivo aumentou de forma linear com a altura da planta (de 8 para 84 perfilhos m-2 quando se comparam plantas de 10 a 40 cm). Os pesos dos perfilhos vegetativos e reprodutivos incrementaram linearmente com a altura da planta. O peso do perfilho vegetativo (0,316 g, em média) foi menor do que o peso do perfilho reprodutivo (0,401 g, em média). A relação entre o número e o peso do perfilho vegetativo foi linear e negativa, enquanto que essa relação, para o perfilho reprodutivo, foi linear e positiva. Em locais com plantas altas há menor número de perfilhos vegetativos, bem como maior número de perfilhos reprodutivos e mortos. Nos locais mais altos do pasto de B. decumbens os perfilhos são mais pesados.The experiment was conducted to study the relationship between the number and weight of tiller categories in Brachiaria decumbens cv. Basilisk pasture managed under continuous stocking with cattle. The pasture was managed with an average height of about 25 cm. Plants offour different heights (10, 20, 30 and 40 cm) were evaluated by means of the randomized block design with two replications. The number of vegetative tillers, both live and total, reduced linearly according to the plant height. The number of reproductive tillers increased linearly according to pasture plant height (from 8 to 84 tillers m-2 when comparing plants 10 to 40 cm high). Vegetative and reproductive tiller weight increased linearly according to pasture plant height. Vegetative tiller weight (0.316 g average) was lower than the reproductive tiller weight (0.401 g average). A linear and negative relationship was found between the number and weight of the vegetative tillers, whereas a linear and positive one was found for the reproductive tillers. There are fewer vegetative tillers, and a greater number of reproductive and dead tillers in places with tall plants. At the places with high B. decumbens plants, tillers are heavier.

O experimento foi conduzido com o objetivo de avaliar a influência das variações naturais da altura da planta no mesmo pasto sobre as características morfogênicas e estruturais da Brachiaria decumbens cv. Basilisk manejada sob lotação contínua com bovinos. Foram avaliadas quatro alturas de plantas (10, 20, 30 e 40 cm) no mesmo pasto manejado com altura média de 25 cm. Adotou-se o delineamento em blocos ao acaso com duas repetições. A taxa de aparecimento foliar do capim-braquiária foi influenciada linear e negativamente pelas alturas das plantas no mesmo pasto. Os perfilhos presentes nos locais com maior altura apresentaram maior filocrono (9,3 dias). A maior altura das plantas no mesmo pasto promoveu maiores taxas de senescência foliar e de alongamento de pseudocolmo no perfilho. A duração de vida da folha (37,8 dias) e a taxa de alongamento foliar (1,3 cm/perfilho.dia) não foram influenciadas pela altura da planta. Os números de folhas vivas (4,36) e mortas (2,15) também não foram modificados pela altura da planta. Já a maior altura das plantas resultou em aumento linear de 69% no número de folhas com desfolhação. Os comprimentos do pseudocolmo e da lâmina foliar responderam linear e positivamente ao aumento na altura da planta no mesmo pasto. A variação natural na altura da planta no mesmo pasto altera as características morfogênicas e estruturais do capim-braquiária. Existe variabilidade espacial da vegetação em pastos de Brachiaria decumbens cv. Basilisk manejados sob lotação contínua com bovinos.The objective of this experiment was to evaluate the influence of natural variation of heights of plants on the same pasture on the morphogenic and structural characteristics of Brachiaria decumbens cv. Basilisk managed under continuous stocking with cattle. Four plant heights (10, 20, 30 and 40 cm) were evaluated on the same pasture managed at an average height of 25 cm. It was used a randomized block design with two replications. Leaf appearance rate of signalgrass was linearly and negatively influenced by heights of the plants on the same pasture. The tillers on the same sites with the highest heights showed greater phyllochron (9.3 days). The higher plant heights on the same pasture promoted both higher leaf senescence and pseudoculm elongation rates for the tillers. Leaf lifespan (37.8 days) and leaf elongation rate (1.3 cm/tillers.day) were not influenced by the plant height. The number of green (4.36) and dead (2.15) leaves was not changed by the plants height either. However, the higher height of plants resulted in a linear increase of 69% on the number of leaves showing defoliation. Pseudoculm and leaf blade lengths responded linearly and positively to the increase in the plants height on the same pasture. The natural height variance of plants found on the same pasture changes the morphogenetic and structural characteristics of signalgrass. There is spatial variability of the vegetation on Brachiaria decumbens cv. Basilisk pastures managed under continuous stocking with bovine.

Objetivou-se avaliar as características morfogênicas e estruturais e o acúmulo de forragem em pastos de Brachiaria decumbens (capim-braquiária) de acordo com a localização das fezes de bovinos. Foram avaliadas duas áreas da pastagem: próxima e distante das fezes. O delineamento foi em blocos casualizados, com três repetições. Foram marcados perfilhos no pasto para avaliação do comprimento de folhas e colmos. O aparecimento e a morte de folhas também foram registrados. A taxa de alongamento de colmo foi 80% maior e a taxa de alongamento foliar 23% maior nos perfilhos das áreas próximas das fezes. O filocrono também foi maior nos perfilhos (8,5 dias) das áreas próximas às fezes em comparação àqueles de áreas distantes (7,7 dias). Não houve efeito da localização das fezes sobre a taxa de senescência foliar (0,39 cm/perfilho.dia) e a duração de vida da folha (38 dias). O comprimento final da lâmina foliar foi 25% maior nos perfilhos localizados próximos às fezes. O número de folhas com desfolhação (1,3 folhas) foi menor nas áreas próximas às fezes, contrariamente ao número de folhas mortas (2,8 folhas). O comprimento do pseudocolmo aumentou 73% com a proximidade das fezes. Os números de perfilhos vegetativos, mortos e total foram maiores nas áreas distantes das fezes. Maior taxa de crescimento total do capim-braquiária também ocorreu nas áreas próximas às fezes. A deposição de fezes bovinas modifica as características morfogênicas e a estrutura do pasto de B. decumbens. Nas regiões próximas às fezes, o fluxo de tecidos é mais intenso e o acúmulo de forragem é maior.The objective of this study is to evaluate morphogenetic and structural characteristics as well as forage accumulation on Brachiaria decumbens pastures according to the site of cattle feces. It was evaluated two grazing areas: near and far from the droppings. The design used was a random block design, with three replicates. Tillers were tagged on the pasture for evaluation of length of the leaves and stems. Leaf appearance and death were also recorded. Stem elongation rate was 80% higher and leaf elongation rate was 23% higher for the tillers near the dropping areas. Phyllochron was also higher for tillers (8.5 days) in sites close to the feces in comparison to those from the distant areas (7.7 days). There was no effect of dropping localization on leaf senescence rate (0.39 cm/tiller.day) and leaf life span (38 days). Final leaf blade length was 25% higher for tillers near the droppings. The number of defoliating leaves (1.3 leaf) was lower in areas near the droppings, contrary to the number of dead leaves (2.8 leaves). Pseudostem length increased 73% as it was closer to the droppings. Number of dead and total vegetative tiller was higher in areas far from the droppings. Higher total growth rate of B. decumbens also occurred in sites close to the droppings. Cattle droppings change the morphogenetic characteristics and structure of B. decumbens pasture. In areas close to the feces, the tissue flow is more intense and forage accumulation is higher.

The objective of this work was to evaluate the morphogenetic and structural characteristics of xaraes palisadegrass submitted to three cutting heights (15, 20 and 25 cm) when the sward reached 95% of light interception during regrowth. The experiment was carried out according to a complete randomized block design with three replications. The sward surface height under the cutting condition of 95% of light interception was very homogeneous with values around 30 cm. The increase in cutting height reduced the leaf elongation rate and the number of live leaves but increased stem elongation rate. As the cutting criterion was the same, before the intense competition for light, the variation in the cutting severity had a small influence on the morphogenetic and structural characteristics of this grass. In the summer, due to the better growth conditions, the plants presented a higher tissue renewal, which was characterized by a higher leaf elongation rate, reduced leaf lifespan and leaf senescence rate when compared to the other season of the year. Under intermittent defoliation conditions, the regrowth of xaraes palisadegrass can be interrupted at a sward height of 30 cm (frequency) keeping a residual height of 15 cm.Este trabalho foi realizado com o objetivo de avaliar as características morfogênicas e estruturais do capimxaraés submetido a três alturas de corte (15, 20 e 25 cm) quando atingidos 95% de interceptação de luz durante a rebrotação. O experimento foi conduzido segundo delineamento de blocos completos casualizados com três repetições. A altura do dossel na condição de corte de 95% de interceptação de luz mostrou-se homogênea, com valores próximos a 30 cm. A elevação na altura de corte reduziu a taxa de alongamento de folhas e o número de folhas vivas, mas aumentou a taxa de alongamento de colmos. Como o critério para a realização dos cortes foi o mesmo, antes da competição intensa por luz, a variação na severidade de corte pouco influenciou as características morfogênicas e estruturais dessa gramínea. No verão, devido às melhores condições de crescimento, as plantas apresentaram maior renovação de tecidos, fato caracterizado pela maior taxa de alongamento foliar, pela menor duração de vida da folha e taxa de senescência de folhas comparativamente à outra estação do ano. Em condições de desfolhação intermitente, a rebrotação do capim-xaraés pode ser interrompida aos 30 cm de altura do dossel (frequência) mantendo-se 15 cm de altura de resíduo.

Objetivou-se identificar, pela avaliação do perfilhamento, as estratégias adequadas de manejo da Brachiaria decumbens cv. Basilisk em lotação contínua com bovinos. Foram estudadas duas estratégias de manejo: pasto com 25 cm de altura durante todo período experimental, epasto com 15 cm no inverno e 25 cm na primavera e verão. Foram adotados o esquema de parcelas subdivididas e o delineamento em blocos casualizados com quatro repetições. As estratégias de manejo foram o fator primário e as estações (inverno, primavera e verão), o fator secundário. O menor balanço entre taxas de aparecimento (TApP) e de mortalidade de perfilhos (TMoP) e o menor número de perfilho vegetativo ocorreram no inverno. Na primavera e verão, o balanço e o número de perfilhos vegetativos foram altos e similares. O rebaixamento do pasto no inverno incrementou o balanço entre TApP e TMoP e o número de perfilhos, em relação à sua manutenção em 25 cm. Houve maiores números de perfilhos reprodutivos e mortos no verão e no inverno, respectivamente. Os pastos com 25 cm possuíram maior número de perfilho morto. Em lotação contínua, o rebaixamento da B. decumbens para 15 cm no inverno e sua manutenção em 25 cm na primavera e verão otimiza sua renovação de perfilhos.The study was conducted to identify, through assessments of tillering, appropriate management strategies for Brachiaria decumbens cv. Basilisk under continuous stocking with cattle. Two management strategies were studied: pasture with 25 cm throughout the experimental period, and pasture with 15 cm in winter and 25 cm in spring and summer. A split-plot and randomized block design with four replications were adopted. The management strategies represented the primary factor, and the seasons (winter, spring and summer) werethe secondary factor. The lowest balance between rates of appearance (TAR) and mortality (TMR) of tillers and the lowest number of vegetative tillers occurred in winter. In spring and summer, the balance and number of vegetative tillers were higher and did not differ. The lowering of pasture in winter resulted in greater balance between TAR and TMR and higher number of tillers in relation to management on sward fixed at 25 cm. There were greater numbers of reproductive and dead tillers in summer and winter, respectively. The pastures with fixed height of 25 cm contained a higher number of dead tiller. Under continuous stocking, the lowering of B. decumbens pasture in winter and its increase to 25 cm in spring and summer optimizes turnover of tillers.

The experiment was carried out aiming to classify and quantify tiller categories of Brachiaria decumbens cv. Basilisk from different heights found on the same pasture. Four different plant heights (10; 20; 30 and 40 cm) living at the same pasture were evaluated. Randomized block design with three replications was used. Tillers were classified according to their stage of development, growth origin, defoliation level and size. The number of vegetative tillers reduced linearly, while the number of reproductive tillers and dead tillers increased linearly according to the plant height. The number of aerial tillers showed a quadratic response in relation to the plant height. The pastures having grasses of 10, 20, 30 and 40 cm in height had respectively 292, 408, 496 and 344 aerial tillers/m2. The population density of defoliated tillers reduced linearly according to the plant height. The population density of tillers without the apical shoot showed quadratic response to the signal grass height, being the smallest values found for places having grasses of 10 cm (176 tillers/m2) and 40 cm (180 tillers/m2) in height. The number of tillers without defoliation quadratic responded to the plant height, being the highest values found for places having grasses extremely high. The areas with the highest grasses also showed the highest numbers of tallest tillers. There is indeed a spatial variability of the vegetation and a high morphological diversity of tillers on Brachiaria decumbens cv. Basilisk pastures managed under the continuous stocking system.

This work was performed aiming to evaluate the morphogenetic and structural characteristics of Andropogon gayanus cv. Planaltina species submitted to three cutting heights (20, 27 and 34 cm). The three cutting heights were allocated in experimental units (12 m²) in a complete randomized block design with three replications. The cuts were done when the light interception by the sward reached 95%. At this moment, the sward height revealed itself constant with values close to 50 cm. The lowest cutting height (20 cm) influenced negatively the final leaf blade length, the number of live leaves, the leaf lifespan, the stem elongation rate and the tiller population density, and it influenced positively the phyllochron and the leaf senescence rate. Probably, cuts at 20 cm height caused a high decapitation and death of the tillers. The worst growth conditions in addition to the blossom of this specie occurred during fall resulted in higher stem elongation rates and number of live leaves, and lower phyllochron, final leaf blade length, and leaf lifespan. The sward height can be used as a practical and efficient criterion in the management of andropogon grass. Under intermittent management conditions, the regrowth of andropogon grass must be interrupted when the sward reaches 50 cm height, and the defoliation must be interrupted when the stubble height is close to 27 cm.Este trabalho foi realizado com o objetivo de avaliar as características morfogênicas e estruturais da espécie Andropogon gayanus cv. Planaltina, submetida a três alturas de corte (20, 27 e 34 cm). As três alturas de corte foram alocadas às unidades experimentais (12 m²) em delineamento de blocos completos casualizados com três repetições. Os cortes foram realizados quando a interceptação luminosa pelo dossel atingiu 95%. A altura do dossel nesse momento mostrou-se constante, com valores próximos a 50 cm. A menor altura de corte (20 cm) influenciou negativamente o comprimento final da lâmina foliar, o número de folhas vivas, a duração de vida da folha, a taxa de alongamento de colmo e a densidade populacional de perfilhos, e positivamente o filocrono e a taxa de senescência de folhas. Provavelmente, cortes a 20 cm de altura causaram elevada decapitação e morte de perfilhos. As piores condições de crescimento junto do florescimento ocorrido durante o outono resultaram em maiores taxas de alongamento de colmos e número de folhas vivas e em menor filocrono, comprimento final da lâmina foliar e duração de vida da folha. A altura do dossel pode ser utilizada como critério prático e eficiente de manejo do capim-andropógon. Em condições de manejo intermitente, a rebrotação deve ser interrompida quando o dossel atingir 50 cm de altura, e a desfolhação, quando a altura de resíduo ficar próxima de 27 cm.

The aim of this work was to compare the structural characteristics of vegetative and reproductive tillers on Brachiaria decumbens cv. Basilisk pastures diferred for 73, 95 and 116 days. Randomized block design in a split plot scheme with three replications was used. The stockpiling period did not influence (P>0.10) the number of vegetative tillers (VT) but increased (P0.10) by the deferring period. The RT revealed (P

Objetivou-se avaliar o efeito da localização das fezes de bovinos sobre as características de perfilhos vegetativos e reprodutivos, a massa dos componentes da planta, a densidade volumétrica da forragem e a altura do pasto de Brachiaria decumbens, cv. Basilisk, manejado sob lotação contínua. O delineamento foi em blocos casualizados, com três repetições, em esquema de parcela subdivida, considerando parcelas os locais próximos e distantes das fezes e subparcelas as categorias de perfilhos vegetativos e reprodutivos. A massa de lâmina foliar viva (LFV) por perfilho em locais próximos às fezes (0,14 g) foi maior que nos locais distantes das fezes (0,08 g), contrariamente ao verificado para a composição de massa de lâmina foliar morta por perfilho. A massa de LFV nos perfilhos vegetativos (0,15 g) foi maior que nos perfilhos reprodutivos (0,06 g). Por outro lado, a massa de colmo (0,38 g) e de lâmina foliar morta (0,20 g) foi maior nos perfilhos reprodutivos. O peso dos perfilhos das plantas próximas às fezes foi maior (0,58 g) que daqueles distantes das fezes (0,17 g). Em locais próximos das fezes, o número de perfilhos vegetativos foi menor, enquanto o de perfilhos reprodutivos foi maior. Maiores massas de colmo verde, forragem verde e forragem total do pasto foram observados nos locais próximos das fezes, quando comparadas aos distantes. Mesmo resultado foi obtido para a altura do pasto. A estrutura do pasto de Brachiaria decumbens é modificada pela localização das fezes dos bovinos em pastejo. A deposição de fezes por bovinos constitui fator de heterogeneidade espacial da vegetação em pastagem.The objective of this study was to evaluate the effect of the cattle feces location on the characteristics of vegetative and reproductive tillers, dry mass content in plant components, forage volumetric density and Brachiaria decumbens cv. Basilisk pasture height managed under continuous stocking. It was used a randomized block design with three repetitions in a split-plot scheme considering the plots the sites next and far from feces and the sub-plots were the vegetative and reproductive tiller categories. Dry mass content of live foliar blade (LFB) per tiller in sites near the feces (0.14 g) was higher than in the sites distant from the feces (0.08 g), opposing to what was verified for composition of dry matter of dead foliar blade per tiller. Content of LFB dry mass in vegetative tillers (0.15 g) was higher than in the reproductive tillers (0.06 g). On the other hand, composition in stem dry matter (0.38 g) and in dead foliar blade (0.20 g) were higher for reproductive tillers. Tiller weight of the plants near the feces was higher (0.58 g) than those far from the feces (0.17 g). On sites near the feces, the number of vegetative tiller was lower, while the number of reproductive tiller was higher. Higher contents of dry matter of the green stem, green forage and total forage of the pasture were observed on sites close to feces when compared to the far ones. The same result was obtained for the pasture height. The Brachiaria decumbens pasture structure is modified by the position of the cattle feces. Cattle feces droppings are a heterogeneous spatial factor of vegetation on grazing areas.

Este trabalho foi conduzido com o objetivo de avaliar as características estruturais da Brachiaria decumbens cv. Basilisk. Foram avaliadas quatro alturas de plantas (10, 20, 30 e 40 cm) dentro de uma mesma pastagem, em um delineamento experimental de blocos casualizados com duas repetições. A variação na altura inicial das plantas no pasto de capim-braquiária apresentou resposta linear e negativa. As massas de lâmina foliar verde, colmo verde, material morto, forragem verde e forragem total aumentaram linearmente com a altura das plantas no pasto. Contrariamente, houve redução linear na relação lâminas foliares verdes/colmos verdes com a altura das plantas no pasto (de 1,16 para 0,58). A altura das plantas no pasto teve efeito mais pronunciado sobre o aumento das massas de colmo verde e material morto que sobre a massa de lâmina foliar verde. A densidade volumétrica de lâminas foliares verdes decresceu (de 97,09 para 39,07 kg/cm.ha de MS) com a altura das plantas no pasto. Mesma resposta ocorreu para as densidades volumétricas de forragem verde (de 181,62 para 107,85 kg/cm.ha de MS) e forragem total (de 283,39 para 195,72 kg/cm.ha de MS). Por outro lado, não houve efeito da altura das plantas no pasto sobre as densidades volumétricas de colmos verdes e material morto, que apresentaram valores médios de 80,95 e 95,61 kg/cm.ha de MS, respectivamente. A altura das plantas no pasto teve efeito quadrático sobre a interceptação de luz pelo dossel. Áreas da pastagem com alturas de 10, 20, 30 e 40 cm apresentaram valores de interceptação luminosa de 56,15; 85,16; 93,39 e 96,57%, respectivamente. Ocorre variação espacial e temporal na estrutura do pasto de B. decumbens manejado sob lotação contínua.This study was carried out aiming to evaluate the structural characteristics of Brachiaria decumbens cv. Basilisk pasture. Four heights of plants (10, 20, 30 and 40 cm) were evaluated within the same grazing area in a randomized block experimental design with two repetitions. Variation in the initial height of the signal grass pasture plant showed a linear and a negative response. The masses of green leaf blade mass, live stem, dead material, live forage and total forage linearly increased with heights of the plants on the pasture. However, it was observed a linear reduction in green leaf blade/live stem ratio and the height of the plants on the pasture (from 1.16 to 0.58). Plant height on the pasture had a stronger effect on the increase of live stem and the dead material masses than it had on the green leaf blade mass. Volumetric density of green leaf blade decreased (from 97.09 to 39.07 kg/cm ha DM) with plant height on the pasture. The same response was found for volumetric densities of live forage (from 181.62 to 107.85 kg/cm.ha dry matter) and total forage (from 283.39 to 195.72 kg/cm.ha dry matter). On the other hand, the plant heights on pasture did not affect volumetric density of live stem and dead material, which showed mean values 80.95 and 95.61 kg/cm.ha DM, respectively. The heights of the plants on pasture had a quadratic effect on light interception by the canopy. Grazing areas with heights of 10, 20, 30 and 40 cm showed light interception values of 56.15, 85.16, 93.39 and 96.57%, respectively. It occurs and temporal variabilities on the B. decumbens pasture structure managed under continuous stocking.

Este trabalho foi realizado com o objetivo de avaliar o valor nutritivo de perfilhos e componentes morfológicos em pastos diferidos e adubados com nitrogênio de Brachiaria decumbens cv. Basilisk. Dois experimentos foram realizados em delineamento de blocos casualizados com três repetições e esquema de parcela subdivida. No primeiro experimento, foram realizadas combinações entre doses de nitrogênio (0, 40, 80 e 120 kg/ha) com os componentes morfológicos (folha verde, colmo verde, folha morta e colmo morto) ou com as categorias de perfilhos (vegetativo e reprodutivo) do pasto. No segundo experimento, estudaram-se as combinações entre períodos de diferimento (73, 95 e 116 dias) com categorias de perfilhos (vegetativo e reprodutivo). A adubação nitrogenada aumentou o percentual de fibra em detergente neutro (FDN) nos colmos verdes e o teor de proteína bruta (PB) nas folhas verdes e mortas e no colmo verde. Elevou também os percentuais de PB nos perfilhos vegetativos e reprodutivos, assim como o teor de FDN do perfilhos vegetativos. Maior período de diferimento causou acréscimo no percentual de FDN e redução no percentual de proteína bruta nos perfilhos vegetativos e reprodutivos. A dose de nitrogênio e o período de diferimento alteram o valor nutritivo dos componentes morfológicos e dos perfilhos dos pastos de B. decumbens cv. Basilisk. No diferimento da pastagem, ações de manejo que resultem em maiores percentuais de lâmina foliar verde e perfilho vegetativo no pasto contribuem para melhorar o valor nutritivo da forragem diferida.This work was carried out aiming to evaluate the nutritional value of tillers and the morphological components on deferred and nitrogen-fertilized pastures of Brachiaria decumbens cv. Basilisk. Two experiments were performed in randomized block designs with three repetitions and subdivided plot scheme. In the first experiment, combinations among nitrogen doses (0, 40, 80 and 120 kg/ha) were performed either with the morphological components (green leaves, green stem, dead leaves and dead stem) or with tiller categories (vegetative and reproductive) of the pasture. In the second experiment, the combinations of the deferring periods (73, 95 and 116 days) with the tiller categories (vegetative and reproductive) were studied. N-fertilization increased neutral detergent fiber (NDF) percentage in the green stem and the content of crude protein (CP) in green leaves, dead leaves, and green stem. N-fertilization also increased CP percentages in the vegetative and reproductive tillers, as well as the NDF content in vegetative tillers. A higher deferring period resulted in an increment of the NDF percentage and a reduction of crude protein percentage in the vegetative and reproductive tillers. Nitrogen dose and the deferring period alter the nutritional value of the morphological components and the tillers of the pastures of B. decumbens cv. Basilisk. For deferring of pastures, management actions that result in higher percentages of green foliar blade and vegetative tiller in the pasture contribute to improve the nutritional value of the deferred forage.

O experimento foi realizado para avaliar o número de perfilhos, a massa de forragem e de seus componentes morfológicos em pastos de Brachiaria decumbens cv. Basilisk durante o diferimento da pastagem. Os tratamentos foram quatro períodos de diferimento (18, 46, 74 e 121dias), a partir de 8/3/2004. O delineamento foi em blocos casualizados com duas repetições. Foram determinados os números de perfilhos vegetativos (PV), reprodutivos (PR) e mortos (PM), bem como as massas de lâmina foliar verde (MLV), colmo verde (MCV) e forragemmorta (MFM). Durante o período de diferimento houve redução no número de PV (de 1.491 para 944 perfilhos m-2). Os números de PR e PM não foram influenciados pelo período de diferimento e suas médias foram 211 e 456 perfilhos m-2, respectivamente. O período de diferimento causou incremento nas MCV (de 2.965 para 4.877 kg ha-1 de massa seca) e MFM (2.324 para 4.823 kg ha-1 de massa seca), porém não influenciou a MLV (em média, 2.047 kg ha-1 de massa seca). Em Viçosa, Estado de Minas Gerais, o pasto de B. decumbens, adubado com nitrogênio e diferido no início de março, pode permanecer diferido por cerca de 70 dias para conciliar produção de forragem em quantidade com boa composição morfológica. This experiment was performed aiming to evaluate tiller population density, forage mass and its morphological components on pastures of Brachiaria decumbens cv. Basilisk. during deferment. The treatments encompassed four deferred grazing periods (18, 46, 74 and 121 days). Arandomized block design with two replications was used. The numbers of vegetative tillers (VT), reproductive tillers (RT) and dead tillers (DT) in the pasture were determined. The masses of green leaf blade (GLBM), dead stem (DSM) and dead forage (DFM) were alsodetermined. There was a reduction in the number of VT (from 1,491 to 944 tiller m-2) during the deferment period. RT and DT numbers were not influenced by the deferment periods. Their averages were 211 and 456 tiller m-2, respectively. Longer deferring periods resulted in an increase in GSM (from 2,965 to 4,877 kg ha-1 of dry mass) and DFM (from 2,324 to 4,823 kg ha-1 of dry mass), but it did not influence GLBM (average of 2,047 kg ha-1 of dry mass). In Viçosa, Minas Gerais State, Brazil, Brachiaria decumbens cv. Basilisk pasture fertilized and deferred in the beginning of March must be kept deferred for about 70 days in order to conciliate both quality and quantity forage production.

Avaliou-se a variabilidade espacial e temporal de características descritoras da condição de pastos diferidos de Brachiaria decumbens cv. Basilisk (capim-braquiária). Os tratamentos consistiram de combinações dos períodos de diferimento da pastagem (73, 103, 131 e 163 dias) com os períodos de pastejo (29, 57 e 85 dias). Utilizou-se esquema de parcelas subdivididas e delineamento em blocos casualizados com duas repetições. Foi determinada a dispersão dos valores de altura do pasto, altura da planta estendida e do índice de tombamento do pasto. A variabilidade espacial da altura do pasto aumentou de forma linear com o período de diferimento, porém não foi influenciada pelo período de pastejo. O coeficiente de variação da altura da planta estendida diminuiu linearmente em pastos submetidos aos maiores períodos de diferimento e não foi afetado pelo período de pastejo. A variabilidade do índice de tombamento, no entanto, apresentou resposta quadrática ao período de diferimento, com ponto de máximo correspondente ao coeficiente de variação de 38,25% aos 130 dias. Em pastagens diferidas por curto período (73 dias), ocorreu variação negativa do coeficiente de variação durante o período de pastejo. Pastos de capimbraquiária sob diferimento por longos períodos possuem maior variabilidade da altura do pasto e menor heterogeneidade da altura da planta estendida. Além do efeito temporal, ocorre grande variabilidade espacial nas pastagens de capim-braquiária diferidas.It was evaluated spatial and temporal variability of status descriptive characters of Brachiaria decumbens (signalgrass) cv. Basilisk deferred pastures. Treatments consisted of combinations of pasture deferring periods (73, 103, 131 and 163 days) with grazing periods (29, 57 and 85 days). Randomized block design with two repetitions and subdivided plots was used. It was determined the dispersion of pasture height (PH), stretched plant height (SPH) and falling index (FI) values. Pasture height spatial variability increased linearly with the deferring period, although it was not influenced by the grazing period. The coefficient of variation of stretched plant height decreased linearly on pastures subjected to longer deferring periods, and it was not affected by the grazing period. However, falling index variability showed a quadratic response to the deferring period, with maximum range corresponding to the coefficient of variation of 38.25% on the 130th day. On pastures deferred for short periods (73 days), negative variation of the coefficient of variation was revealed during the grazing period. Brachiaria decumbens pastures under longer deferring periods have higher pasture height variability and lower stretched plant height heterogeneity. Besides the temporal effect, high spatial variability occurs on Brachiaria decumbens deferred pastures.