RESUMO O objetivo desse trabalho foi delimitar áreas aptas e o requerimento hídrico de irrigação para cultivo do capim Tanzânia no estado do Ceará. A produtividade do capim Tanzânia foi obtida a partir de um modelo matemático que assume os valores da evapotranspiração real, resultante do balanço hídrico climatológico da cultura. A necessidade hídrica para reposição de água ao longo do ano para solos com capacidade de água disponível de 20 (solos rasos), 40 (solos arenosos), 60 (solos de textura média) e 100 mm (solos argilosos). A partir da TAMS obteve-se a frequência relativa de ocorrência de produtividade mensal em diferentes municípios Cearense. Os valores de produtividade do capim Tanzânia no estado do Ceará predominaram entre 20.000 e 30.000 kg MS ha-1 ano-1. Durante os meses chuvosos o potencial produtivo varia em função da mesorregião econômica, as quais apresentam condições climáticas distintas. Portanto, o estado do Ceará possui aptidão para produção do capim Tanzânia, sob regime de sequeiro, durante apenas quatro meses, predominantemente, de fevereiro a maio, sendo que as condições climáticas não favorecem o desenvolvimento do capim nos demais meses.

ABSTRACT This study aimed to define areas suitable, and the irrigation water requirement for, cultivation of Tanzania guineagrass in the state of Ceará, Brazil. Tanzania guineagrass yield was estimated by a mathematical model, which considers the crop actual evapotranspiration, resulting from the crop climatological water balance. The water requirement throughout the year was estimated for soils with a water holding capacity of 20 (shallow soils), 40 (sandy soils), 60 (soils with medium texture) and 100 mm (clay soils). The relative frequency of occurrence of monthly productions greater than 2,750 kg DM ha-1 month-1 was obtained for different areas in Ceará, representative of most of the state's economic mesoregions. Tanzania guineagrass annual yields in the state of Ceará were between 20,000-30,000 kg DM ha-1 year-1. During the rainy season, the productive potential varies with the economic mesoregion, which presents different climatic conditions. The state of Ceará is only suitable for the rainfed production of Tanzania guineagrass for 4 months each year, predominantly from February to May, while weather conditions do not favor the development of this grass in the remaining months.

O experimento foi desenvolvido em casa de vegetação na Embrapa Pecuária Sudeste, utilizando acessos de Brachiaria brizantha. O delineamento experimental foi o de blocos ao acaso, com arranjo fatorial 2 X 4, sendo dois tratamentos (com e sem déficit hídrico) e quatro genótipos. O grupo de genótipos avaliado foi formado pelas cultivares 'BRS Piatã', 'Marandú', 'Xaraés' e 'BRS Paiaguás', sendo o experimento realizado durante o mês de julho de 2008. As variáveis analisadas foram massa seca total, massa seca de parte aérea, massa seca de raiz, massa seca de colmo, massa seca de folha, taxa de alongamento foliar, área foliar, área foliar específica. O estresse por deficiência hídrica exerceu efeito negativo em todas as características estudadas e em todos os acessos avaliados. A cultivar 'BRS Piatã' foi o genótipo que menos apresentou alteração entre os tratamentos com e sem déficit hídrico, indicando portanto, tolerância dessa cultivar em relação ao estresse por falta de água no solo nessas condições experimentais

The experiment was conducted in a greenhouse at Embrapa Southeast Livestock, using Brachiaria brizantha accessions. The experimental design was fully randomized blocks with a 2 x 4 factorial arrangement, with two treatments (with and without water deficit) and four genotypes. The group evaluated was formed by genotypes 'BRS Piatã', 'Marandu', 'Xaraés' and 'BRS Paiaguás'. The experiment was conducted during the month of July 2008. The variables analyzed were dry mass of total plant, shoot mass, leaves, stems and roots, leaf elongation rate, leaf area and specific leaf area. The water deficit stress exerted negative effect on all characteristics studied and in all accessions. 'BRS Piatã' was the genotype that showed less change between treatments with and without water deficit, thus indicating tolerance of this cultivar in relation to water stress in the soil under these experimental conditions

In this study, the microclimate changes in silvopastoral systems are quantified at different time and spatial scales and compared with single-pasture systems. The study was conducted in a silvopastoral system in São Carlos, Brazil (22°01' South and 47°53' West). The silvopastoral system consisted of grass pastures [Urochloa (sin. Brachiaria) decumbens cv. Basilik] lined with strips of native trees spaced at 17 m. Continuous microclimate measurements (air temperature, relative humidity, wind speed, and incident photosynthetically active radiation) were carried out from September 2010 to September 2012 at two positions of the silvopastoral system (2.0 and 8.5 m from the rows of trees) and at a pasture under full sunlight, located in an adjacent area. The soil moisture was monitored weekly from 24 March 2010 to 1 April 2012 at distances of 0.0, 2.0, 4.75, and 8.5 m from the rows of trees. The rows of native trees reduced wind speeds (46% reduction) and changed the photosynthetically active radiation incidence pattern on the pasture (up to 40% reduction of incidence at the point nearest to the trees). The combined action of these factors promoted thermal and air humidity changes on the pasture at the different points measured. With respect to soil moisture, there was greater soil moisture removal at the sampling points near the rows of native trees under the silvopastoral system, mainly due to enhanced exploration by tree roots at greater depths in dry spells or early dry periods, when compared with the midpoints between the rows.

O objetivo deste trabalho foi avaliar a produtividade e as características biométricas do capim-braquiária (Urochloa decumbens) sob pastejo, em sistema silvipastoril. Avaliou-se um sistema com árvores nativas de interesse comercial, plantadas em renques, no sentido norte-sul, espaçados por 17 m. Utilizou-se o delineamento experimental de blocos ao acaso, com quatro repetições e parcelas subdivididas, tendo-se avaliado o ciclo de rebrota da forragem nas parcelas, e a distância desta em relação aos renques, nas subparcelas. Sete ciclos de rebrota foram avaliados, em quatro distâncias dos renques: a 2 e a 6 m do renque leste, e a 2 e a 6 m do renque oeste. Quantificou-se a produtividade de matéria seca, o índice de área foliar (IAF), a área foliar específica (AFE) e a altura das plantas. A produtividade de forragem, nos dois primeiros ciclos, e o IAF, no segundo e no terceiro ciclo, diminuiram com níveis de sombra acima de 39 e 40%, respectivamente. Já a altura de plantas aumentou com sombreamentos superiores a 53%, nos quatro primeiros ciclos; o que também ocorreu com a AFE, com sombreamento superior a 66%, nos três primeiros ciclos.

The objective of this work was to evaluate the productivity and biometric characteristics of signal grass (Urochloa decumbens) under grazing, in a silvopastural system. A system with native trees of commercial interest, planted in a set of rows with north-south orientation, with 17 m spacing was evaluated. A randomized complete block design with four replicates was carried out in a split-plot arrangement, with forage grass regrowth cycles evaluated in the plots and distances from trees in the subplots. Seven regrowth cycles were evaluated at four distances of the set of tree rows: at 2 and 6 m from trees at east, and at 2 and 6 m from trees at west. Dry matter productivity, leaf area index (LAI), specific leaf area (SLA), and plant height were measured. Forage productivity in the first two cycles and LAI in the second and third cycles reduced with shading levels higher than 39 and 40%, respectively. However, plant height increased with shadings greater than 53%, in the first four cycles, and SLA with shadings greater than 66%, in the first three cycles

Climatic risk zoning allows the identification of areas of low risk of reduced crop productivity due to climatic events. In Brazil, losses to agriculture due to climate are mainly caused by drought. The objective of this research was to determine areas of low climatic risk for corn and palisade grass cultivated in integrated crop-livestock systems in Sao Paulo state. Corn varieties characterized by a 120-day growing cycle and soil with three different water holding capacities (sandy, medium and clayey soils) were considered. A daily water balance model was used to simulate planting dates between September and December. The water requirement satisfaction index (WRSI) was calculated for critical phenological phases of both cultures (germination, emergence and tillering of palisade grass and flowering and grain filling of corn). The WRSI values, calculated for a minimum frequency of 80%, were located spatially using the SPRING v. 5.1 geographic information system and the most favorable periods for sowing in different areas were determined. The results showed that there are areas of low climatic risk for cultivation of corn and palisade grass in integrated crop-livestock production systems in Sao Paulo state. Although climatic risk in these areas also depends on soil type, the most favorable period for planting is between October and November.

The objective of this work was to evaluate yield traits and development of palisadegrass under the influence of water deficit during the establishment period. The experiment was carried out in a greenhouse, in a completely random block statistical design in a factorial arrangement and additional treatment (3 × 3 + 1). The treatments referred to the suppression of irrigation at different phases of the establishment (sowing, germination and initial tillerring) until the soil presented water content of 75%, 50%, and 25% of the moisture related to field capacity (qFC), besides control treatment with no water restriction. Evaluations of number of grown tillers per vase, green leaves per tiller and plant height were carried out weekly, for five weeks after the first tillers appeared. Biomass sampling was carried out approximately 30 days after the end of the last applied treatment, when the soil was kept close to 100% of field capacity relative moisture. Tillering and biomass yield of palisadegrass during establishment phase are reduced when water deficit is sufficient to make soil content water reach 25% of relative moisture field capacity, regardless to the season when water shortage takes place.

The objective of this work was to evaluate the development and productive traits of palisadegrass single cultivated or intercropped with corn, in addition to corn intercropped with pasture, under water deficit at different development stages of the plants. It was used a complete block experimental design with split plots and three replicates. Periods of water deficit were placed in the plots and types of cultivation were placed in the subplots. Irrigation was stopped at germination and initial tillering of palisadegrass and at V4 and V15 stages of corn and returned when soil moisture was 40% of available water capacity. Tiller density and palisadegrass height were evaluated weekly. Dry matter (DM) of fractions of herbage mass as well as leaf area of the plants were evaluated at corn tasseling and when grains reached physiological maturity. Components of corn production were determined in the second sampling. In palisadegrass, water influenced only tillering, which was reduced in the plots in which water defict was forced at the moment of germination or at the beginning of tilering, in both cultivation systems. Plant height and DM production were affected only by cultivation, reducing when intercropped with corn. Evaluated production components did not influence corn grain productivity, which was similar in all treatments (average of 10,145 kg/ha). Palisadegrass plants produce more DM in single cultivation than intercropped with corn. Water deficit during germination and initial tillering reduces tillering of palisadegrass during establishment phase. Water deficit, applied in this trial, does not reduce DM yield in palisadegrass or corn.

O trabalho foi realizado com o objetivo de avaliar as características morfogênicas de Panicum maximum x Panicum infestum cv. Massai submetido a quatro doses de nitrogênio (0, 40, 80 e 120 mg/dm³) e três regimes de desfolhação (três, quatro e cinco folhas completamente expandidas), em um esquema fatorial 4 x 3, em um delineamento inteiramente casualizado, com quatro repetições. Após semeadura, transplantio e desbaste, três plantas permaneceram em vasos com capacidade para 5,8 dm³ de solo. As adubações fosfatada e potássica foram realizadas de acordo com os resultados da análise do solo. A adubação nitrogenada, via solução aquosa, de acordo com os tratamentos experimentais, foi parcelada em quatro vezes. Quando as plantas apresentavam o número de folhas expandidas indicador da desfolhação, foram colhidas e avaliadas quanto às características morfogênicas. Ao findar o período experimental, as plantas foram colhidas e levadas à estufa, para determinação do teor de MS. A taxa de alongamento foliar (TAlF) aumentou linearmente até 64% na dose de 120 mg/dm³ de N, em comparação à ausência de nitrogênio. O filocrono reduziu com a adubação nitrogenada. A produção de MS da parte aérea do capim-massai e a relação lâmina:colmo aumentaram linearmente com as doses de N e a redução do número de folhas expandidas antes da colheita.

This work was carried out to evaluate the morphogenetic and structural characteristics of the hybrid Panicum maximum x Panicum infestum cv. Massai in response to four nitrogen doses (0, 40, 80 and 120 mg/dm³) and three defoliation intervals (two, three and four completely expanded leaves), in a 4 x 3 factorial treatment combination. The experiment was carried out in greenhouse according to a completely randomized design, with four replications. Sowing was achieved in plastic tray filled with sand and seedlings were transplanted to pots with 5.8 dm³ of soil. Pots were thinned to three plants/pot. The phosphate and potash fertilization was accomplished according to soil fertility analysis. The nitrogen fertilization was split in four applications in aqueous solution, according to the experimental doses. As the plants presented the number of expanded leaves, indicating their defoliation interval, they were harvested to 5 cm from soil level; this harvest marked the beginning of the evaluation period of the morphogenetic and structural characteristics of the grass. At the end of these evaluations, the plants were harvested, dried and weighted. Nitrogen fertilization doses had marked effects on the morphogenetic and structural characteristics of Massaigrass, as well as on its shoot dry weight. Leaf elongation rate (TAlF) showed linear increase of 64% to N doses. The phyllochron decreased as nitrogen dose increased. Shoot dry matter weight and lamina:stem ratio increased linearly with the increment of N doses but decreased as the number of expanded leaves increased before harvest.

O trabalho foi realizado com o objetivo de se avaliarem as características morfogênicas e estruturais de Brachiaria brizantha cv. Xaraés, submetido a quatro doses de nitrogênio (0, 40, 80 e 120 mg/dm³) e três regimes de desfolhação (três, quatro e cinco folhas completamente expandidas), em um esquema fatorial 4 x 3. O experimento foi conduzido em casa de vegetação, com os tratamentos dispostos em um delineamento inteiramente casualizado, com quatro repetições. Após desbaste, foram mantidas três plantas por vaso com capacidade de 5,8 dm³. As plantas receberam adubação fosfatada e potássica, de acordo com análise de fertilidade do solo. A adubação nitrogenada, via solução aquosa, foi parcelada em quatro aplicações. Quando apresentaram número de folhas expandidas indicador de corte, as plantas foram colhidas a 5 cm do solo, iniciando-se as avaliações das características morfogênicas e estruturais. Os resultados indicaram que o nitrogênio tem efeito sobre as características morfogênicas e estruturais e sobre a produção de MS, com exceção da MS radicular. Observou-se incremento de até 37% na taxa de alongamento (cm/dia) para a mais elevada dose de N (120 mg/dm³ ) em relação ao tratamento sem adubação nitrogenada. A freqüência de corte influenciou a taxa de alongamento foliar, o filocrono, o comprimento final da lâmina, o número de folhas vivas por perfilhos, a taxa de senescência e o teor matéria seca da parte aérea e raiz.

The morphogenetic and structural traits of Brachiaria brizantha cv. Xaraés submitted to the treatment combinations of four nitrogen rates (0, 40, 80 and 120 mg/dm3) and three defoliation frequencies (two, four and five completely expanded leaves) were evaluated according to a 4 x 3 factorial arrangement. The experiments were conducted in a greenhouse, with the treatments arranged as factorial combination. The experimental design was completely randomized, with four replications. After thinning, three seedlings were left per pot (5,8 dm3). The phosphate fertilization was performed according to the soil fertility. The pots were fertilized with phosphorus and potassium, according to soil fertility. Nitrogen fertilization was split in four applications and applied in aqueous solution. When the plants reached the number of expanded leaves (defoliation moment), they were cut at 5 cm height from soil level before evaluation of morphogenetic and structural traits in the aftermath. Significant nitrogen effect was observed on morphogenetic and structural characteristics of xaraésgrass and on DM yield, except on root DM. Leaf elongation rate (LER) increased linearly up to 37% at the N rate of 120 mg/dm³. Defoliation influenced leaf elongation rate, phyllochron, blade length, number of live leaves per tiller, senescence rate and dry matter yield of shoot and root.

Com o objetivo de reavaliar agronomicamente 17 linhagens de guandu, originárias de acessos anteriormente selecionados por diversas características de interesse agronômico, foram instalados experimentos em cinco locais do Estado de São Paulo. A confirmação dessas características foi necessária, uma vez que as amostras de sementes dos acessos originais apresentavam mistura mecânica e segregação, razão pela qual, após serem selecionados, os acessos passaram por processo de purificação em condições controladas de polinização. Nesses experimentos, as linhagens foram submetidas a cortes para avaliação da produção de forragem, ocasião em que foram determinados o número de plantas na área útil da parcela e a altura média dessas plantas. Foi também determinado o teor de proteína bruta e de taninos de amostras da forragem produzida. Entre as linhagens testadas, g58-95 e g127-97 confirmaram ter plantas de baixa estatura, g3-94, g167-97 e g29b-94 confirmaram oferecer boas produções de forragem e g146-97 destacou-se quanto à produção inicial de matéria seca.

With the purpose of re-evaluating seventeen pigeon-pea lines originated from accessions previously selected for favorable agronomic characteristics, experiments were installed in five locations of the State of São Paulo. The confirmation of those characteristics was necessary because the original accessions presented various degrees of mechanical mixtures and segregation and were submitted to purification process in pollination controlled conditions. In those trials, the lines were cut in several occasions to evaluate forage yield. Each time, it was determined the number of plants in each parcel and its average height. Also it was determined their crude protein and tannins contents. Among the tested lines, g58-95 e g127-97 confirmed to have low plants, g94, g167-97 and g29b-94, confirmed to offer good forage yields, while line g146-97 presented good initial forage yields.

O uso do programa de Cornell indica a necessidade de estudos sobre a degradação dos diferentes componentes da matéria seca (MS). O objetivo deste trabalho foi avaliar a cinética ruminal da MS e das frações fibra em detergente neutro (FDN), proteína bruta (PB) e proteína insolúvel em detergente neutro (PIDN) de amostras de capim-Tanzânia (Panicum maximum Jacq.) obtidas por simulação de pastejo, coletadas em três épocas do ano (verão, outono e primavera), em pastagens irrigadas submetidas a três níveis de resíduo pós-pastejo (baixo, médio e alto). Para cada período de incubação, foram usados três animais fistulados no rúmen. Os tempos de incubação foram: 0, 3, 6, 9, 12, 24, 30, 48, 60, 72, 96 horas. No resíduo do material incubado, foram determinados os teores de FDN, PB e PIDN, utilizando-se NIRS. O nível de resíduo baixo foi o tratamento que apresentou maior redução de degradabilidade potencial entre o verão (81,41%) e a primavera (74,96%). A fração prontamente solúvel da proteína pode ser maior que 40% da proteína degradável no rúmen (PDR), que variou entre 76,36 e 62,05% da PB. A fração indegradável da FDN (C) é maior que a estimada pelo CNCPS a partir dos teores de lignina/FDN multiplicados por 2,4. Os resultados deste trabalho indicam que o fator de multiplicação deve estar entre 2,91 e 3,35. A fração C do PIDN (12,11 a 17,08%) é maior que a calculada em laboratório como nitrogênio aderido à fibra em detergente ácido (N-FDA) (6,48 a 10,7%). Quanto maior o teor de PB e de PIDN, pior a degradabilidade da PB.

The objective of this work was to study DM, NDF, CP and IPND ruminal kinectics of irrigated Tanzaniagrass (Panicum maximum Jacq.). Simulated grazed samples were collected on three periods of the year (spring, summer and fall), under three post grazed stubbles intensities (low, medium and high). Three rumen cannulated animals were assigned to a 3 x 3 Latin square design to determine the in situ degradability until 96 hours of incubation. NDF, CP and IPND were determined by NIRS in the residue remaining in the bags. Forage quality was the highest in the summer. The low post grazed stubble treatment showed the highest increase in degradability of all fractions from spring (74.96%) to summer (81.41%). The soluble protein fraction showed values up to 40% of the RDP, which ranged from 62 to 76% CP. NDF C fraction was underestimated by CNCPS. Data of this research suggest that the %lignin/%NDF should be multiplied by a factor from 2.91 to 3.35. CNCPS overestimated the IPND C fraction (12.11 to 17.08%), as compared to the wet lab analysis value, as regarded to be the N-ADF fraction (6.48 to 10.7%). CP and IPND degradability decreased, as the CP and IPND contents increased.

Foram realizados dois experimentos para avaliar o efeito de três freqüências de pastejos (28, 38 e 48 dias) sobre a massa de forragem, a taxa de acúmulo de matéria seca (MS) e a relação folha:haste (F:H) em Tanzânia e Mombaça, no período de setembro de 1995 a maio de 1996. O delineamento experimental foi em parcelas subdivididas, sendo a parcela representada pela freqüência de pastejo e as sub-parcelas pelos períodos do ano. A massa de forragem por pastejo foi maior quando a freqüência de pastejo foi menor, porém não teve efeito sobre a taxa de acúmulo de MS nos cultivares Tanzânia e Mombaça. A taxa de acúmulo de matéria seca para os dois cultivares foi maior em janeiro/fevereiro; portanto, nesta época, deve-se trabalhar com freqüências de pastejo ou lotações mais elevadas. A relação folha:haste dos dois cultivares foi baixa, principalmente durante a fase reprodutiva, indicando que se deve trabalhar com freqüências de pastejo mais elevadas (pastejos a cada 28 dias ou menos), a fim de controlar o desenvolvimento das hastes.

Two experiments were carried out to evaluate the effects of three grazing frequencies (28, 38 and 48 days) on forage mass, dry matter (DM) accumulation rate and leaf:stem ratio in Tanzania and Mombaça, from September 1995 to May 1996 period. A split plot experimental design was used, with grazing frequency as main plots and period of the year as subplots. The forage mass per grazing was greater when the grazing frequency was small, however did not have an effect on the DM accumulation in the Tanzania and Mombaça cultivars. The rates of forage accumulation for the two cultivars were greater in January/February; so we should work with greater grazing frequency or stocking rate. The leaf:stem ratio of the two cultivars was small, mainly during the reproductive phase, indicating that we should work with greater grazing frequency (grazing at each 28 days or less) in order to control the stems development.