RESUMOAvaliaram-se os efeitos de diferentes tipos de cobertura morta de solo de origem vegetal sobre o crescimento, controle de plantas daninhas, produtividade e regime hidrotérmico do solo no cultivo da cenoura, cultivar Brasília, em um experimento conduzido no período de setembro a dezembro de 1998, em Marília, SP. O delineamento experimental utilizado foi o de blocos casualizados, com cinco tratamentos e quatro repetições em parcelas de 2 m 2 . Estudou-se os seguintes tipos de cobertura: serragem de madeira, casca de arroz, maravalha (raspa de madeira), capim seco (Cynodon spp.) e controle (solo sem cobertura morta). A utilização da cobertura morta de solo mostrou-se como uma prática vantajosa para o cultivo de verão da cenoura, reduziu a temperatura em até 3,5ºC, aumentou a retenção de umidade do solo em até 2,3% em relação ao controle e melhorou o desenvolvimento das plantas de cenoura. Houve menor incidência de plantas daninhas com o uso de maravalha e capim seco que, juntamente com a serragem também aumentaram o número de plantas colhidas. Entre os tipos de cobertura morta utilizados, a casca de arroz e a maravalha se destacaram em relação ao solo descoberto como os materiais que proporcionaram maior produtividade (112,6 e 99,6 t/ha respectivamente). O uso de cobertura morta de solo mostrou-se vantajoso em vários aspectos para cultura da cenoura, sendo técnica e economicamente viável, principalmente, em pequenas áreas e em cultivos orgânicos. Termos para indexação:Daucus carota L., cobertura morta, plantas daninhas, produtividade. ABSTRACTThe effects of different mulches were evalueted on carrot culture, cultivar Brasilia, in a experiment carried out at Marilia, São Paulo State, Brazil, from september to december/1998. The experimental design was a randomized block with four replications and size plots of 2 m 2 . Wood dust, wood chips, dry grass (Cynodon spp.), rice straw and control (soil without cover) were tested and their effects on the soil hidrothermal regime, weed control, growth and yield of carrot were determined. Mulching materials showed better carrots plants development, mild soil temperature (3,5°C less control trait) and better soil moisture (2,3% high control trait). Dry grass and wood chips showed lower weed infestation and dry grass, wood chips and wood dust increased carrot stand. Mulches with rice straw and wood increased carrot yield (112,6 e 99,6 t/ha respectively). Mulching use is technically and economically viable for carrot growing, mainly in small areas and in organic farms. INTRODUÇÃONo Brasil, a cenoura (Daucus carota L.) é cultivada durante o ano todo, havendo cultivares específicas para o outono-inverno, primavera e verão. Entretanto, no cultivo de verão ocorrem uma série de intempéries climáticas que podem prejudicar, tanto a germinação das sementes como o desenvolvimento da planta e qualidade das raízes.No verão também ocorre maior disponibilidade de água e altas temperaturas, favorecendo assim a ocorrência de plantas daninhas nas áreas de cultivo. A intensidade das interf...

-The objective of this experiment was to estimate the curve of dehydration, chemical composition and in vitro dry matter digestibility (IVDMD) and crude protein digestibility (IVCPD) of tifton 85 hay, produced single or overseeded with ryegrass or white oat IPR 126. The experimental design was in randomized blocks, in a 3 × 10 factorial arrangement, with three cropping systems and ten evaluation times (0, 4, 8, 24, 28, 32, 48, 52 and 56 and 71 hours after harvest) during the dehydration process. For chemical composition and in vitro DM and CP digestibility, the experimental design was in randomized blocks with three cropping systems and three evaluation times (before cutting, before baling and 100 days after of storage). It was found that tifton 85 intercropped with white oat kept its higher nutritional value after storage, with 19.78% crude protein and 70.03% of in vitro dry matter digestibility. The participation of white oat in tifton 85 area was 57.04% and for ryegrass, it was 38.52%, but the dry matter yield of single tifton 85 was higher than other intercrops. Thus, it is recommended an oversowing of winter annual species on Tifton 85, without moisture restriction, because of the benefits obtained in the hay nutritional value.

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RESUMOO experimento foi conduzido na Fazenda Experimental da Unioeste, Marechal Cândido Rondon, PR, Brasil, com o objetivo de avaliar os efeitos de doses crescentes de N sobre características estruturais e composição química de três gramíneas forrageiras tropicais. O delineamento experimental utilizado foi o em blocos casualizados em esquema fatorial 3 x 4, com três forrageiras tropicais (Panicum maximum cvs. tanzânia e mombaça, e Brachiaria sp. cv. mulato) e quatro doses de N (0; 40; 80 e 160 kg/ha) tendo como fonte a uréia. Foram avaliados: a altura do dossel, a relação folha/colmo, a proporção de folhas e de colmos na forragem produzida, o diâmetro e a altura do pseudocolmo, e os teores de proteína bruta (PB), fibra em detergente neutro (FDN), fibra em detergente ácido (FDA) e matéria mineral (MM). Houve efeito das doses de N sobre a altura do dossel e sobre a altura do pseudocolmo, que apresentaram comportamento quadrático. A relação folha/colmo respondeu de forma negativa às doses de N, enquanto o diâmetro do pseudocolmo foi influenciado apenas pelas forrageiras. Para o teor de PB foi constatada significância da interação dos fatores, de forma que na dose de 80 kg/ha de N o capim tanzânia foi superior aos demais. Os teores de FDN responderam de forma quadrática às doses de N, enquanto os teores de FDA foram influenciados apenas pelas forrageiras. SUMMARYThe experiment was carried out in the experimental farm of Unioeste, Marechal Candido Rondon, PR, Brasil, with the objective of evaluate the effects of increasing N doses under structural features and chemical composition of three tropical forage grasses. The experimental design used was of randomized blocks in factorial scheme 3x4, with three tropical forages (Panicum maximum cvs. tanzânia and mombaça, and Brachiaria sp. cv. mulato) and four doses of N (0; 40; 80 and 160 kg/ha) taking urea as N sources. Were evaluated: canopy height leaf/stem ratio, diameter and height of pseudoculm, and contents of crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and mineral matter (MM). There was effect of N doses on canopy height and height of pseudoculm that showed quadratic behavior. The leaf/stem ratio responded negatively to N doses, while the diameter of pseudoculm was influenced only by forages. For CP content was found significance of interaction of factors, being that in dose of 80 kg/ha of N the Tanzania grass was higher than the other. The contents of NDF responded of form quadratic to N doses, while the contents of ADF were influenced only by forages. INTRODUÇÃOAs pastagens pela sua praticidade e

O presente trabalho objetivou avaliar os efeitos de doses crescentes de nitrogênio sobre as características morfogênicas, estruturais e produtivas das gramíneas Panicum maximum cvs. Mombaça e Tanzânia, e Brachiaria sp. Mulato. O experimento foi conduzido em condições de campo. O delineamento experimental utilizado foi de blocos casualizados em esquema fatorial 3x4, com três forrageiras (Panicum maximum cvs. Tanzânia e Mombaça e Brachiaria sp. cv. Mulato), quatro doses de N (0, 40, 80 e 160 kg ha -1 ), com três repetições. Foram avaliados os seguintes parâmetros: produção de massa verde (PMV), produção de massa seca (PMS), altura de planta, porcentagem de massa seca, folhas por perfilho, taxa de acúmulo de massa seca (TAMS) e eficiência de uso de nitrogênio (EUN). Os capins Mombaça e Tanzânia apresentaram resultados semelhantes, e ambos foram superiores ao capim Mulato quanto à produção de matéria verde e seca. As três espécies forrageiras responderam a aplicação de nitrogênio, com aumento na produção de MS, MV, TAMS, altura e número de perfilhos. A eficiência máxima no uso do N foi obtida com a dose de 120 kg ha -1 . Palavras-chave: Brachiaria, Panicum, taxa de acúmulo DOI: 10.5433/1679 AbstractThis study aimed to evaluate the effects of increasing doses of nitrogen on the morphogenesis, structural and productive grass Panicum maximum cvs. Mombaca and Tanzania, and Brachiaria sp. Mulato. The experiment was conducted under field conditions. The experimental design was randomized blocks in a 3x4 factorial design with three forages (Panicum maximum cvs. Tanzania and Mombaca and Brachiaria sp. cv. Mulato), four N rates (0, 40, 80 and 160 kg ha -1 ) with three replications. Were evaluated the following parameters: fresh matter production (FMP), dry matter production (DMP), plant height, percentage of dry matter, leaves per tiller, dry matter accumulation rate (DMAR) and nitrogen use efficiency (NUE). Grasses Mombasa and Tanzania showed similar results, and both were superior

-White oat and ryegrass were overseeded on Tifton 85 pastures for evaluation of dry matter yield (DMY), leaf:stem ratio (L:S), dehydration curves and nutritional value of forages. Dry matter intake and L:S ratio were analyzed using a completely randomized blocks design with five forage growth conditions (single Tifton 85 and intercropped with white oat or ryegrass, and white oat or ryegrass intercropped with Tifton 85), whereas for drying curves, ten dehydration times were tested (0, 4, 8, 24, 28, 32, 48, 52, 56 and 71 hours after harvest) by a 5 × 10 split-plot arrangement (growth conditions of forages as main plot and dehydration times as sub-plots). The nutritive value data were analyzed in a 3 × 3 split-plot trial with single Tifton 85, Tifton 85 -Oat and Tifton 85-Ryegrass as main plots and the three sampling times (before harvesting, at baling and 100 days after storage) as sub-plots. Oat and ryegrass showed higher L:S ratio, while the intercrops of Tifton 85 -Oat and Tifton 85 -Ryegrass presented lower DMY, but higher crude protein concentration and in vitro DM digestibility than single Tifton. Neutral and acid detergent fiber concentrations were higher for single Tifton 85. Ryegrass and white oat, overseeded on Tifton 85 pasture, improved the nutritional value of the hay produced; however, in a 100-day storage period, there was a reduction in in vitro dry matter digestibility and crude protein concentrations.

-The objectives of this study were to estimate the curve of dehydration, bromatological composition and occurrence of fungi in Tifton 85 grass, submitted to four methods of dehydration. The curves of dehydration were studied in a completely randomized design with a 4 × 11 factorial scheme with four drying systems (1 conditioning + 1 turn-over; 2 conditionings + 1 turn-over; no conditioning + 1 turn-over and no conditioning + 2 turn-overs) and 11 sampling times (0, 3, 15, 18, 21, 24, 39, 42, 45 and 47 hours after the cutting), with six replicates. For the bromatological composition and fungi occurrence, the experimental design was completely randomized in a 4 × 3 factorial scheme with the four drying methods of Tifton 85 grass and three periods of evaluation (before the cutting, at the time of the baling and 30 days after storage) with six replicates. It was found that after the first hour after cutting and at the end of the period of dehydration, Tifton 85 plants that were treated with conditioners showed higher levels of dry matter. Stored hay that was treated with conditioners presented higher levels of acid detergent insoluble protein. Until baling, the drying methods did not alter the crude protein content of hay; however, after storage, the hay submitted only to turn-over showed crude protein content higher (13.90%) than those submitted to conditioners (9.94%). There was an increase in the occurrence of fungi after storage, but the application of conditioners and one turn-over resulted in lower CUF/g, compared with other treatments, enhancing the effect of conditioners on accelerating the dehydration rate and obtaining better hay storage conditions.

The objective of this study was to evaluate the influence of five levels of N and two regrowth intervals on the structural, productive, and nutritional characteristics of Tifton 85 grass (Cynodon spp). The experiment was conducted in a hay production field at the State University of West Paraná, planted in 2004 with Cynodon spp. cv. Tifton 85. The experiment was established in a randomized block design with factorial treatments of five N fertilization amounts (0, 25, 50, 75 and 100 kg ha -1 cut -1 ) applied as urea after each cut, and two regrowth intervals (28 and 35 d), with four replicates. N application promoted changes in plant structure, such as increased canopy height, stem length, leaf elongation rate, and dry mass (DM) production. The greatest N use efficiency, considering the four harvests, occurred in the plot with 25 kg N ha -1 cut -1 at the 35-d interval, with a production of 13.79 kg DM kg -1 of N applied. A nutritional analysis indicated that 100 kg ha -1 of N cut -1 promoted higher crude protein (CP) at 28 d, with the highest concentration observed in the fourth cut (208.2 g kg -1 DM) and the lowest in the second cut (140.12 g kg -1 DM). The content average in the four cuts for CP and LIG at 28 days of regrowth was 175.85 and 104.33 kg -1 g MS and at 35 days of regrowth interval was of 164.45 and 118.65 g kg -1 DM, respectively. No differences were found between regrowth intervals in the contents of mineral matter and acid detergent fiber (ADF). Environmental factors including the wide variation in precipitation (greater than 200 mm between the peak in December 2010 and the lowest in March 2011) greatly influenced Tifton 85 grass production, affecting DM and the nutritional value of the forage in each cut. Key words: Biomass. Forage quality. Grazing. Management. Persistence. Stocking. ResumoO objetivo do trabalho foi avaliar a influência de cinco doses de nitrogênio (N) em duas idades de rebrota no capim Tifton 85 (Cynodon spp.) sobre as características estruturais, produtivas e na composição bromatológica. O experimento foi instalado no campo de produção de feno da UNIOESTE, campus de Marechal Cândido Rondon. O delineamento experimental foi em blocos casualizados em esquema fatorial 5x2, sendo cinco doses de nitrogênio (0, 25, 50, 75 e 100 kg ha -1 ) aplicados em cada corte, aplicadas na forma de uréia, duas idades de rebrota (28 e 35 dias) com quatro repetições e quatro cortes.