Forage mass and structure of piatã grass deferred at different heights and variable periods

The objective of this study was to determine the deferment period and the most adequate initial sward height of Brachiaria brizantha cv. Piatã for deferment in the region of Viçosa, Minas Gerais. For so, the following characteristics were evaluated: masses and bulk density of forage and its morphological components, light interception by the sward, leaf area index, leaf angle, sward and extended tiller height and falling index of the deferred piatã grass. The three deferment periods assessed (65, 85 and 105 days) were randomized to the plots and the three sward heights (20, 30 and 40 cm), randomized in the subplots. The experimental design was of completely randomized blocks, with three replicates, in a subdivided plots arrangement. Masses of forage, green stem and dead tissue were higher in the piatã grass managed with deferment period of 105 days. The mass of green leaf blade was higher in the piatã grass deferred with 20 cm height associated to the deferment period of 85 days, which had, as consequence, greater bulk density of green leaf blade. The interception of light by the sward was greater in the piatã grass kept longer in deferment associated with the higher leaf area index, regardless of its initial height. The heights of the sward and extended tillers were greater in the piatã grass under periods of 85 and 105 days of deferment; however, the falling index was not affected by the factors studied. In the region of Viçosa, Minas Gerais, B. brizantha cv. Piatã fertilized with 75 kg/ha nitrogen and deferred with initial height of 20 cm and for a period of 85 days, from mid April, has adequate productivity and structure for animal production

Morphogenesis and structural characteristics of Brachiaria humidicola submitted to combinations heights of post-grazing residue a frequency of defoliation

O trabalho foi conduzido com o objetivo de avaliar a influência de práticas de manejo baseadas em combinações de frequências de desfolhação e alturas de resíduos pós-pastejo sobre a dinâmica do fluxo de biomassa da planta em pastos de Brachiaria humidicola cv. Comum, em sistema de pastejo com lotação intermitente. O experimento foi conduzido no Setor Forragicultura do Departamento de Zootecnia, na Universidade Federal de Viçosa, de dezembro de 2009 a dezembro de 2010 em Viçosa-MG. O delineamento experimental foi de blocos completos casualizados com três repetições, em esquema fatorial 2 x 2 e um total de 12 unidades experimentais. Foram avaliados quatro tratamentos, representados por duas alturas de resíduo póspastejo de 8 e 16 cm, combinadas a duas frequências de desfolhação (quando o dossel interceptava 95% ou 98% da luz incidente). A interceptação de luz incidente (IL) e a altura do dossel foram monitoradas semanalmente. Para a avaliação das características morfogênicas foram identificados perfilhos, os quais funcionaram como unidade amostral. As variáveis resposta avaliadas foram: taxa de aparecimento foliar (TApF), filocrono (FILO), taxa de alongamento foliar (TAIF), comprimento final da lâmina foliar (CFLF), número de folhas vivas por perfilho (NFV), taxa de senescência foliar (TSeF), taxa de alongamento de colmo (TAIC), comprimento do colmo (CC) e duração de vida da folha (DVF). Os dados obtidos nos ciclos de pastejo foram transformados em médias ponderadas para estações do ano e analisados segundo o modelo de parcelas subdivididas no tempo utilizando se o PROC MIXED (modelos mistos) do pacote estatístico SAS. Foi utilizado o teste t de Student a 10% de significância. A altura pré-pastejo do dossel, associada a 95% de IL, foi em média, 30 cm, enquanto a altura associada a 98% de IL foi, em média, 50 cm. Pastejos mais frequentes ou mais severos foram caracterizados por maiores TApF, reduções no filocrono, menor CFLF, DVF, TAIF, TAIC, CC e TSeF. Os fatores climáticos e o estádio fisiológico também influenciaram as características morfogênicas e o fluxo de biomassa. As estações favoráveis ao crescimento das plantas verão e primavera foram as de maior TApF, TAIF, CFLF, NFV, TAIC, TC decrescendo nas estações de outono e inverno. O filocrono e a DVF tiveram padrão de resposta inverso, sendo os maiores valores registrados no inverno, intermediários no outono e os menores no verão. A TAIC teve aumento pronunciado na primavera, coincidindo com o período de florescimento da espécie em que há alocação de carbono para o pseudocolmo elevando a TAIC. Pastos de Brachiaria humidicola em pastejo intermitente devem ser manejados com altura pré-pastejo de 30 cm.The study was conducted in order to evaluate the influence of management practices based on combinations of desfolation frequency and heights of stubble on the flow dynamics of plant biomass in pastures of Brachiaria humidicola cv. common, in intermittent grazing system. The experiment was conducted in the sector of Forage-growing, Department of Animal Science, Federal University of Viçosa, from December 2009 to December 2010 in Viçosa-MG. The Experimental outline utilized was of randomized complete blocks with three replications in a factorial 2 x 2 and a total of 12 experimental units. Four treatments were evaluated, represented by two Heights of post-grazing residue (8 and 16 cm), associated with two defoliation frequencies (when the canopy intercepted 95% or 98% of incident light). The interception of incident light (IL) and canopy height were monitored weekly. For the evaluation of morphogenesis features tillers were used, which worked as the sampling unit. The response variant evaluated were: leaf appearance rate (LAR) phyllochron, leaf elongation rate (LER), leaf blade length (LBL), number of live leaves per tiller (NLLT), leaf senescence rate (LSR), stem elongation rate (SER), stem length (SL) leaf lifespan (LL). The data obtained in the grazing cycles were transformed into weighted averages for seasons and analyzed as a split-plot model in time using the "PROC MIXED" (mixed models) statistical package SAS. It was used the Student t test at 10% significance. The pre-grazing height of the canopy, associated with 95% of IL, was on average 30 cm, while the time associated with 98% IL was on average 50 cm. More frequent grazing or more severe were characterized by higher LAF, phyllochron reductions, lower LBL, LL, LER, SER, SL and LSR. Climatic factors and physiological stage also influenced the morphogenesis features and tissue flow. The seasons favorable for plant growth spring and summer were the most LAF, LER, LBL, NLLT, SER, SL decreased during autumn and winter. Phyllochron and LL had opposite behavior, and the highest values were recorded in winter, intermediate in autumn and lowest in summer. SER had a pronounced increase in spring, coinciding with the flowering period of the specie in which there is allocation of carbon to the pseudostems raising the SER. Brachiaria humidicola pastures in intermittent grazing should be managed with pre-grazing height of 30 cm.Conselho Nacional de Desenvolvimento Científico e Tecnológic

<b>Número de perfilhos do capim-braquiária em regime de lotação contínua</b> - doi: 10.4025/actascianimsci.v33i1.10440 <b>Tiller number in signalgrass under continuous stocking systems</b> - doi: 10.4025/actascianimsci.v33i1.10440

Objetivou-se identificar, pela avaliação do perfilhamento, as estratégias adequadas de manejo da <em>Brachiaria decumbens</em> cv. Basilisk em lotação contínua com bovinos. Foram estudadas duas estratégias de manejo: pasto com 25 cm de altura durante todo período experimental, e pasto 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 <em>B. decumbens</em> para 15 cm no inverno e sua manutenção em 25 cm na primavera e verão otimiza sua renovação de perfilhos.<br>The study was conducted to identify, through assessments of tillering, appropriate management strategies for <em>Brachiaria decumbens</em> 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) were the 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 <em>B. decumbens</em> pasture in winter and its increase to 25 cm in spring and summer optimizes turnover of tillers

Diversidade de perfilhos em pasto de Brachiaria decumbens manejado em regime de lotação contínua

O experimento foi conduzido com o objetivo de classificar e quantificar as categorias de perfilhos de Brachiaria decumbens cv. Basilisk existentes em locais com alturas variáveis em um mesmo pasto. Os tratamentos foram quatro alturas de plantas (10, 20, 30 e 40 cm) avaliadas dentro de uma mesma pastagem. O delineamento experimental foi em blocos casualizados, com três repetições. Os perfilhos foram classificados quanto ao estádio de desenvolvimento, à origem de crescimento, ao nível de desfolhação e ao tamanho. O número de perfilho vegetativo reduziu linearmente, enquanto que os números de perfilhos reprodutivos e mortos incrementaram linearmente com a altura da planta no mesmo. O número de perfilho aéreo apresentou padrão de resposta quadrático em função da altura da planta, sendo que os locais do pasto com 10, 20, 30 e 40 cm de altura possuíram, respectivamente, 292, 408, 496 e 344 perfilhos aéreos/m2. A densidade populacional de perfilhos desfolhados reduziu de forma linear com a altura da planta. A densidade populacional de perfilhos sem o meristema apical apresentou resposta quadrática à altura da planta de capim-braquiária, observando-se os menores valores nos locais com 10 cm (176 perfilhos/ m2) e com 40 cm (180 perfilhos/m2) de altura. O número de perfilhos sem desfolhação respondeu de forma quadrática à altura da planta, com maiores valores nos locais do pasto com as alturas extremas. Os locais mais altos do pasto possuíram maior participação de perfilhos mais compridos. Em pasto de Brachiaria decumbens cv. Basilisk manejada em lotação contínua existe variabilidade espacial da vegetação e grande diversidade morfológica de perfilhos.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/m 2 . 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/m 2 ) and 40 cm (180 tillers/m 2 ) 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

Characterization of tillers of piata palisade grass deferred in the fall with varying heights and deferment periods

This study was conducted to evaluate the tiller population density and its structural characteristics in Brachiaria brizantha cv. Piata subjected to deferment periods (65, 85 and 105 days) and initial sward heights for deferment (20, 30 and 40 cm). A completely randomized block design was used in a split-plot scheme with three replications. The population density of vegetative basal and total tillers was influenced by the interaction between periods and initial heights of deferment, with lower values in the period of 85 days associated with the initial height of 40 cm and the period of 105 days associated with initial heights of 30 and 40 cm. The length of the stem and leaf blade of vegetative basal tillers increased with the raise in the deferment periods. Initial deferring heights had little effect on the structural characteristics of the tillers. The concomitant use of tall plants and long deferring periods reduces tillering of piata palisade grass. To optimize the tillering and structure of the deferred pasture in the region of Viçosa, piata palisade grass should be deferred with an initial height from 20 to 40 cm in early May and remain deferred for 65 days.Este trabalho foi conduzido para avaliar a densidade populacional de perfilhos e as características estruturais de perfilhos em Brachiaria brizantha cv. Piatã submetida a períodos de diferimento (65, 85 e 105 dias) e alturas iniciais do dossel para o diferimento (20, 30 e 40 cm). Utilizou-se o delineamento experimental de blocos completos casualizados, em esquema de parcelas subdivididas com três repetições. A densidade populacional de perfilhos basais vegetativos e totais foi influenciada pela interação entre períodos e alturas iniciais de diferimento, com menores valores no período de 85 dias associado à altura inicial de 40 cm e no período de 105 dias associado às alturas de 30 e 40 cm. O comprimento de colmo e da lâmina foliar dos perfilhos basais vegetativos aumentou com o aumento nos períodos de diferimento. As alturas iniciais de diferimento tiveram pouco efeito sobre as características estruturais dos perfilhos. O emprego concomitante de plantas altas e longos períodos de diferimento reduz o perfilhamento do capim-piatã. Para otimizar o perfilhamento e a estrutura do pasto diferido na região de Viçosa, MG, o capim-piatã deve ser diferido com altura inicial de 20 a 40 cm, no início de maio e permanecer diferido por 65 dias

Grazing patterns on signalgrass pasture according to location of cattle feces

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

Characterization of tillers in deferred Piata palisade grass with different initial heights and nitrogen levels

This experiment was conducted to estimate the effects of nitrogen fertilization associated with the initial height of the Piata palisade grass on the number and structural characteristics of individual tillers after the deferment period. An area with Brachiaria brizantha cv. Piata measuring approximately 288 m² was used. Combinations of levels of nitrogen fertilization (0, 75 and 150 kg/ha of nitrogen) and initial heights of the sward (low - 20 cm, medium - 30 cm and high - 40 cm) were evaluated. The experimental design was of completely randomized blocks in subdivided plots with three replications. The number of vegetative tillers, the stem length of the vegetative, reproductive and dead tillers, and the number of dead leaves of the reproductive and the dead tillers linearly increased with the elevation in the nitrogen level. The deferred Piata palisade grass with low initial height showed lower number of dead basal tillers, shorter length of stems and leaf blades in reproductive tillers and lower number of live and dead leaves in vegetative tillers in relation to the one managed with height considered medium and high. Nitrogen fertilization, in association with low initial height, provides the optimization of forage of Piata palisade grass in deferment conditions

Piata palisadegrass deferred in the fall: effects of initial height and nitrogen in the sward structure

The objective of this study was to evaluate the mass of the forage and of the morphological components, and the sward structure in Piata palisadegrass (Brachiaria brizantha cv. Piata) deferred in function of different initial heights and nitrogen levels. Two levels of nitrogen (75 and 150 kg/ha) and one control without fertilization associated to three initial deferring heights (20, 30, and 40 cm) were evaluated. The design was of completely randomized blocks with three replications in a subdivided plot scheme. A raise in the initial deferment height and in the fertilization elevated the sward and extended tiller heights, the leaf area index, and the light interception by the sward. The piata palisadegrass deferred with an initial height of 40 cm presented a higher forage mass with lower percentage of leaf blades, and higher stem and dead tissue quantity. Additionally, this management strategy resulted in lower bulk density of leaf blade and in higher bulk densities of stems and dead tissue. The utilization of 150 kg/ha of nitrogen raised the production and the bulk density of deferred piata palisadegrass forage and increased production and bulk density of leaves and stems. In the region of Viçosa, Minas Gerais, the piata palisadegrass deferred with an initial height of 30 cm and fertilized with 75 kg/ha of nitrogen in the beginning of the fall presents adequate mass and structure to animal production in the winter