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Sugarcane (Saccharum officinarum L.) is one of the most important crops in Brazil and its growth and development can be simulated through process-based models. The current study evaluated a model based on the decision support system for the transfer of Agrotechnology DSSAT/CANEGRO to simulate the sugarcane crop productivity in the western region of São Paulo. The DSSAT/CANEGRO model was calibrated using published yield parameters from a selection of five Brazilian sugarcane cultivars, while sugarcane yield data (tons of stems per hectare) from commercial land were used as benchmark data. Other modeling inputs were derived from the primary regional cultivar. The root mean square error (RMSE), Willmott agreement index (d), and mean absolute error (MAE) were used as performance metrics. The DSSAT/CANEGRO model resulted in a good RMSE performance. The productivity estimates were better for the cultivars SP791010 and RB835486, with RMSE equal to 2.27 and 4.48 Mg ha-1, respectively. The comparison between model-based estimates and observed data produced d values in the range from 0.86 to 0.99, and MAE values in the range of 1.84 to 4.22 Mg ha-1.

In Brazil, the largest producer of sugarcane in the world, the industrial process transforms this crop into ethanol and/or granulated sugar. Some cultivars exhibit enzymatic browning in the extracted sugarcane juice at levels harmful to the manufacturing process of white granulated sugar. The objective of this study was to assess the effect of sugarcane straw used as soil coverage, the use of different planting systems, and treatments with hydrogel polymer on enzymatic activity. The cultivar RB 86 7515 was sampled for 8 months; the first sample was obtained by cutting the upper portion of the stalk at the internode, which was taken to the laboratory for determination of the enzymatic activity of polyphenoloxidase (PPO) and peroxidase (POD). The soil coverage with different forms of straw as well as the planting systems did not change the enzymatic activity of polyphenoloxidase (PPO) and peroxidase (POD). The polyphenoloxidase (PPO) activity increased with the use of a polymer due to increased polyphenoloxidase (PPO) activity in the groove system. The enzymes studied showed changes in activity during the experimental period. The production of sugar at the end of the season (August to November) avoids the periods of highest enzymatic activity. No Brasil, o maior produtor de cana-de-açúcar do mundo, o processamento industrial transforma a cana-de-açúcar principalmente em etanol e/ou açúcar cristal. Alguns cultivares apresentam escurecimento enzimático no caldo extraído em níveis prejudiciais ao processo de fabricação do açúcar cristal branco. O objetivo da pesquisa foi avaliar o efeito do palhiço como cobertura, sistemas de plantio e tratamentos com polímero hidrogel em atividades enzimáticas. O cultivar RB 86 7515 foi amostrado por oito meses, retirando-se o primeiro entrenó da parte superior, que foi levado ao laboratório e procedeu-se à determinação das atividades da polifenoloxidase (PFO) e da peroxidase (POD). As coberturas do solo com diferentes formas de palhiço, bem como os sistemas de plantio, não promoveram alterações nas atividades enzimáticas das enzimas polifenoloxidase (PFO) e peroxidase (POD). A atividade da PFO foi incrementada com a utilização de polímero, este fato foi promovido pelo aumento de atividade da PFO no sistema de plantio em sulco. As enzimas estudadas apresentaram mudanças de atividades nos meses. A produção de açúcar no final da safra (agosto a novembro) evita os períodos de maiores atividades enzimáticas.

TAXA DE CRESCIMENTO RELATIVO DA Brachiaria brizantha cv. Xaraes e Brachiaria brizantha cv. Marandu SOB FERTIRRIGACAO NITROGENADA CATARINY CABRAL ALEMAN¹; ERICK MALHEIROS RAMPAZO 2 E TADEU ALCIDES MARQUES 2 ¹Departamento de Engenharia Agricola, UFV, Avenida PH Rolfs, s/n, 36570-000, Vicosa, MG, Brasil, e-mail: catariny@ufv.br ²Departamento de Agronomia, UNOESTE, Rodovia Raposo Tavares, km 572, 19067-175, Presidente Prudente, SP, Brasil, e-mail: tmarques@unoeste.br, erickrampazo@hotmail.com 1 RESUMO O objetivo do trabalho foi avaliar a taxa de crescimento relativo da Brachiaria brizantha cv. Xaraes e Brachiaria brizantha cv. Marandu submetido a diferentes diluicoes de ureia na agua de irrigacao. O experimento foi conduzido sob esquema fatorial considerando 2 especies de pastagem e 6 doses de nitrogenio diluidas na agua de irrigacao com 5 repeticoes. As diluicoes de nitrogenio foram: 0, 900, 1800, 3200, 4000 e 4800 mg L -1 . Determinou-se a taxa de crescimento relativo considerando a altura inicial e final de cada ciclo de crescimento (primeiro e segundo corte). No primeiro corte, as parcelas que nao receberem nitrogenio apresentaram a maior taxa de crescimento. No segundo corte ocorreu diferencas significativas entre Xaraes e Marandu. Na pastagem Xaraes e na Marandu a diluicao de 4000 mg L -1 e 4800 mg L -1 apresentaram a maior taxa de crescimento relativo. Palvras-chave: pastagem, manejo de irrigacao, nitrogenio, eficiencia da adubacao. ALEMAN, C. C.; RAMPAZO, E. M.; MARQUES, T. A. GROWTH RATE FOR THE Brachiaria brizantha cv. Xaraes and Brachiaria brizantha cv. Marandu UNDER FERTIRRIGATION NITROGEN 2 ABSTRACT The objective was to evaluate the relative growth rate of the Brachiaria brizantha cv. Xaraes and the Brachiaria brizantha cv. Marandu subjected to different dilution of urea in the irrigation water. The experiment was conducted in factorial design considering two species of grassland and 6 nitrogen doses diluted in irrigation water with five repetitions. The nitrogen dilutions were 0, 900, 1800, 3200, 4000 and 4800 mg L -1. A relative growth rate was determined, considering the initial and final point of each growth cycle (first and second cut). In the first cut, the portions that did not receive nitrogen had the highest growth rate. The second cut showed significant differences between Xaraes and Marandu. In the Xaraes pasture and Marandu dilution of 4000 mg L- 1 and 4800 mg L- 1 there was the highest relative growth rate. Keywords: pasture, irrigation management , nitrogen fertilization efficiency.

This study assessed the photosynthesis, biomass, and phytoenergy production in sugarcane plants subjected to water deficit during the initial stages of development. We hypothesize that the limitations imposed by water deficit on photosynthesis proportionally affect carbon balance, growth, and partitioning of phytoenergy in sugarcane. This study was carried out during 5 months in a growth chamber and water deficit was induced by maintaining soil moisture at 20 % of the maximum water holding capacity (WHC). As control, one group of plants was maintained at 100 % WHC. Water deficit reduced the carboxylation of Rubisco and PEPCase significantly, which were the main limiting factors for photosynthesis. As consequence, the daily leaf carbon balance was significantly reduced by drought. The total accumulated dry matter in well-watered plants was 3.6 times higher than in drought-stressed ones. Water deficit reduced the energy accumulated in sugarcane plants by approximately threefold. Regardless of water regime, a large fraction of the converted energy was not found in stalks. Under water deficit, less than 20 % of the energy is stored in stalks. Since only a tiny fraction of solar energy is used for the production of first generation ethanol, our study reinforces the importance of evaluating strategies to optimize the use of sugarcane, for example, harvesting plant organs other than stalks.

O objetivo deste trabalho foi estudar o comportamento de sementes de gabiroba em relação ao ponto de colheita, armazenamento e implicações na germinação. Para caracterização e ponto de colheita foram avaliados frutos de sete plantas, determinando-se o diâmetro, massa fresca de casca, polpa e sementes, número de sementes por fruto, graus Brix da polpacorrigidos para 20(0)C e germinação das sementes recém colhidas, sem retirada da mucilagem. O estudo do armazenamento compreendeu o experimento um, onde foram comparados os seguintes tratamentos: sementes frescas postas para germinar imediatamente após a retirada da mucilagem e outras armazenadas em frasco de vidro fechado a 25(0)C e a 8(0)C e em saco de papel a 25ºC e 60%UR, por 30 dias. O experimento dois (resistência à dessecação) consistiu na instalação diária da germinação (por cinco dias) e na verificação do grau de umidade das sementes mantidas em ambiente de laboratório (25(0)C e 60%UR), considerando-se como testemunha as sementes frescas (primeiro dia), logo após a retirada da mucilagem. No experimento três, os frutos foram armazenados por 20 dias: a temperatura média de 25(0)C, dentro de uma vasilha de louça coberta com uma peneira; em saco de polietileno a 8(0)C e a -18(0)C. As sementes frescas, de frutos não armazenados, foram consideradas a testemunha. Os tratamentos foram avaliados pela germinação (25(0)C), índice de velocidade de germinação e determinação do grau de umidade. O ponto de colheita de frutos de Campomanesia adamantium, para obtenção de sementes, pode ser determinado pela medida do Brix da polpa, indicando-se a colheita dos frutos com no mínimo, 15,75(0) para se obter 95% de germinação. As sementes de guabiroba indicam que a espécie pode ser classificada como recalcitrante, por não suportarem armazenamento a baixa temperatura e nem a dessecação; o armazenamento em frasco de vidro fechado a 25(0)C mantém as sementes com 60% de germinação, por 30 dias. Todavia, a semeadura logo após a extração dos frutos, permite índices de germinação de, no mínimo, 74%. The aim of this study was to investigate the gabiroba seed behaviour regarding the harvesting point, storage and their implications in germination. For characterization and harvest point, fruits of seven plants were evaluated for diameter, peel, pulp and seed fresh matter, number of seeds per fruit, Brix degrees of pulp corrected to 20(0)C and extracted seed germination, with mucilage. The storage study was made up of three experiments. In the first experiment the following treatments were compared with fresh seeds: immediately after the mucilage removal, a second one stored in glass jars at 25(0)C, another at 8(0)C and the last in paper bag at 25(0)C and 60%RH, during 30 days. The second experiment (resistance to desiccation) was done by germinating seeds left at 25(0)C and 60%RH during five days, and moisture determination considering fresh seeds as control. For the third experiment, the fruits were stored for 20 days as follows: at room temperature (25(0)C) in a ceramic bowl covered by a nylon mesh; in polyethylene bags at 8ºC and at -18ºC. Fresh seeds, from non-stored fruits, were used as control. Treatments were evaluated by germination (25(0)C), germination speed index (IVG) and moisture determination. It was concluded that the fruit harvest point might be determined by the Brix degrees of the pulp and it was indicated that fruit would be harvested with at least 15,75(0) to obtain 95% of germination. Campomanesia adamantium seed behaviour showed that the species must be classified as recalcitrant, either by not supporting storage or by not tolerating desiccation. The storage in tightly closed glass jars at (25(0)C) maintained the germination at 60%, for 30 days. However, sowing the seeds, immediately after the extraction from the fruits gave germination indexes of at least 74%.

Para estudar os efeitos do deficit hidrico na producao de bioenergia e nos parâmetros biometricos e tecnologicos da cana-de-acucar, foi estudado dois tratamentos: 100% da reposicao da evapotranspiracao (controle) e 20% de reposicao da evapotranspiracao (deficit hidrico), com 10 repeticoes para cada tratamento. Foram realizadas e avaliadas analises biometricas, tecnologicas e calorimetrica. Sob deficit hidrico as plantas de cana-de-acucar tiveram reducao na biomassa e nos components avaliados (ATR, Pol, Brix e Fibra). A bioenergia total do sistema foi reduzida na mesma proporcao da biomassa, apresentando mudancas em sua composicao. Ja os acucares simples (glucose e fructose) tiveram menor reducao do que os componentes bioenergeticos.

In the specific case of sugarcane, producers in Brazil are currently paid by the content of total recoverable sugars (TRS) in the raw material when it reaches the industry, according to CONSECANA: TRS = 9.6316 *PC +9.15 * RSS, where PC is the Pol in cane (apparent sucrose) and RSS are reducing sugars in sugarcane (glucose + fructose). The objective of the project was to propose changes in the procedures used to mathematically determine the TRS, estimating the calorific value of moist cake and weight of moist cake. The final model is then proposed: TRS = 25.9892 + 0.02172*CVmc*WMC+0.536*WMC – 4.14*CVmc + + 4.8158*PC + 4.575*RSS. Thus we obtain the TRS calculated according to the calorific value of moist cake (CVmc), weight of moist cake (WMC), Pol cane (PC) and the reducing sugars in sugarcane (RSS). This form is included in the estimation of TRS, the calorific value of moist cake, which reflects the bioenergy of fiber, weight of moist cake that estimates sugarcane fiber, in addition to existing factors Pol cane and reducing sugars in sugarcane. In the proposed model, the estimated values of TSR were 11.08% higher than the estimated values in the CONSECANA model.

1 RESUMO Polimeros hidroabsorventes sao utilizados na agricultura para proporcionar o uso racional da agua. O presente trabalho teve como objetivo compreender a interferencia da utilizacao de polimero hidroabsorventes e diferentes profundidades de plantio (sulco e leira), nos parâmetros biometricos, produtividade final e atributos de qualidade industrial da cana-de-acucar. As variaveis de controle do ensaio abrangeram parâmetros biometricos, nas fases de crescimento, parâmetros de produtividade e qualidade tecnologica na colheita, em dois ciclos. O experimento foi realizado em Presidente Prudente (SP), com o cultivar RB 86 7515 sendo plantado em dezembro de 2007 e colhido em junho 2009 (cana planta - 18 meses) e julho de 2010 (cana soca - 12 meses). Para os dois ciclos utilizou-se o esquema de blocos ao acaso, com dois blocos (plantio em leira e plantio em sulco), quatro tratamentos (0,00; 26,67; 53,33 e 80,00 kg ha -1 do polimero no plantio) e oito repeticoes. O polimero hidroabsorvente alterou a biometria, aumentando o perfilhamento e proporcionou maior produtividade em cana planta e menor queda na produtividade de cana soca, apresentou correlacao com Acucares Totais recuperaveis (ATR) da cana-de-acucar. O sistema de plantio em leira apresentou menor queda de produtividade e maior perfilhamento, com as doses mais elevadas de polimero. PALAVRAS-CHAVE: canteirizacao, Saccharum spp, condicionador de solo. MARQUES, T. A.; dos SANTOS, A. T.; MARQUES, P. A. A. THE HYDROGEL POLYMER AND DEPTH OF PLANTING IN SUGARCANE PRODUCTION 2 ABSTRACT In order to provide the rational use of water in agriculture hydrogel polymers can be used. The aim of the present study was to indentify the interference of hydrogel polymers and different plantation depth (furrow and windrow) on biometrics parameters, final productivity and industrial quality attributes of sugarcane. The variables used were: biometrics parameters during the vegetative growth stage, and the final yield and technological quality of sugarcane, in two production cycles. The experiment was conducted in the city of Presidente Prudente, state of Sao Paulo, Brazil, with the RB 86 7515 sugarcane variety being planted in December 2007 and harvested in June 2009 (first harvest - 18 months) and in July 2010 (ratoon cane - 12 months). For the two cycles were used a randomized block design with two blocks (planting in the furrow and windrow) and with four treatments (0; 26.67; 53.33 and 80.00 kg of polymer per hectare) with eight repetitions. The hydrogel polymer modified the biometric, increasing the tillering and providing higher productivity in sugarcane plant. Besides, it caused the smallest decrease in sugarcane ratoon crop yield and showed to have a correlation with the total recovered sugar of sugarcane. With higher doses of hydrogel polymer the windrow planting system presented lower decrease in productivity and higher tillering. KEYWORD: windrow, Saccharum spp, soil conditioner.