352 resultados para Taxa de acúmulo de matéria seca
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Pós-graduação em Zootecnia - FCAV
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In tropical regions there is rapid decomposition of plant material deposited on the soil, and the ability to recycle nutrients through this decomposition is one of the most important aspects of cover crops. The aim of this study was to evaluate the yield and nutrient release from forage crops intercropped with maize for silage, and soybean in succession. The study was conducted in the experimental area of Universidade Estadual Paulista, Ilha Solteira campus, Brazil. The experiment consisted of maize for silage intercropped with four forage species (Urochloa brizantha cv. Marandu, Urochloa ruziziensis, Panicum maximum cv. Tanzania, and Panicum maximum cv. Aries) sown in three modalities: in the maize row, together with fertilizer; broadcast at maize sowing; and broadcast in the V4 stage of maize, in a randomized block design in a 4 x 3 factorial arrangement with four replications. The evaluation of nutrient release was performed during the soybean cropping that followed the intercropping by the litter bag method at 30, 60, 90, and 120 days after sowing of soybean. Panicum maximum cv. Tanzania showed higher dry matter yield when sown by broadcasting at maize sowing. Sowing of forages in the maize row, and through broadcasting at maize sowing led to greater dry matter yield for straw formation. Intercropping of maize with forages in the autumn is an alternative for increasing the amount of straw and cycling of macronutrients in a no-till system. Potassium was the nutrient with the greatest accumulation in the forage straws (up to 150 kg ha(-1)), with 100 % release at 90 days after sowing soybean. The forage straws are thus an excellent alternative for cycling of this nutrient. Panicum maximum cv. Tanzania sown by broadcasting at the time of maize sowing showed greater phosphorus cycling (13 kg ha(-1)). Panicum maximum cv. Tanzania broadcast in the V4 stage of maize is the option with least potential for straw production and nutrient cycling, while the other options (forages and sowing modalities) have higher potential for use, at the criteria of machine availability for setting up intercropping with corn.
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Objective of this work by evaluating the effect of nitrogen on forage yield and morphogenesis of elephant grass cv. Pioneer. The experimental design was randomized blocks with five replications, totaling 20 experimental units. Treatments consisted of four nitrogen levels (100, 200, 300 and 400 kg ha(-1) yr(-1)). The experiment was conducted under irrigated conditions. Evaluative cuts were made at 50 cm soil with values of light interception (95%) without pre-defined intervals. It was observed that N fertilization increased significantly (P<0.05) the production of dry matter per hectare, leaf appearance rate (leaves days(-1)tiller(-1)), leaf elongation rate (cm tiller(-1) day(-1)) and stem elongation rate (cm day(-1)). The process of this forage senescence is accelerated with increasing doses of nitrogen and leaf appearance rate, thereby reducing the phyllochron. It required a study on the economic viability of higher doses of nitrogen in grazed elephant grass cv. Pioneer.
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Currently, the use of herbicides is essential in a practical and common in agricultural areas, but efficiency of these herbicides can be compromised when applied on plants that thrive in water deficit conditions, due to low uptake and translocation of the product. Therefore, the aim of this study was to compare the efficiency of control ACCase inhibiting herbicides applied post-emergence in plants of Eleusine indica under different soil water contents. The experiment was conducted in a greenhouse and the experimental design was completely randomized design with four replications, consisting of a 9x4 factorial, with the combination of three soil water potentials (-0.03, -0.07 and -1.5 MPa) three herbicides (fluazifop-p -butyl, haloxyfop-methyl and sethoxydim + oil) and four doses (0, 25, 50, and 100 % of the recommended dose). Herbicide application was made in plants in vegetative stage 2-3 tillers. The soil water potential was initiated in the development stage of two leaves, and the water was supplemented until the soil reaches the potential of -0.01 MPa, when it came to minimum pre-determined for each water management. The physiological parameters evaluated were: photosynthetic rate, stomatal conductance, transpiration leaf temperature and plant dry mass. The visual assessments of phytotoxicity were performed at 7 and 14 days after application. The herbicides behaved in different ways according to the used water management. In severe water stress conditions (soil moisture at 8%) only fluazifop-p-butyl herbicide achieved satisfactory control (> 90%) in E. indica plants.
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Fueron conducidos dos experimentos individuales en el municipio de Mossoró, Rio Grande do Norte, Brazil. Se empleó dos cultivares de melón, ‘Olimpic express’ (del tipo Cantaloupo) e ‘Iracema’ (del tipo Amarillo), para evaluar el crecimiento y la acumulación de macronutrientes, bajo el diseño de bloques al azar con siete tratamientos (épocas de muestreo) y tres repeticiones. Los muestreos de plantas fueron realizados a los 14, 21, 28, 35, 42, 49 y 56 días después del trasplante (DDT). El crecimiento fue lento hasta 28 DDT en ambos cultivares evaluados, intensificándose en el periodo siguiente, alcanzando a los 56 DDT, 246.4g planta-1 , en ‘Olimpic express’,y 266.9 g planta-1, en ‘Iracema’, siendo la materia seca (MS) de los frutos correspondientes a 60% y 64% de la MS total, respectivamente. Mayores acumulaciones de N, P y K fueron obtenidos en los frutos, mientras de Ca, Mg y S en las hojas. Al final del ciclo, en ‘Olimpic express’, cuya productividad fue de 32 t ha-1, fueron acumulados 173.4, 110.1, 101.1, 26.9, 15.6 y 13.5 kg ha-1 de K, Ca, N, Mg, S y P, respectivamente, y en ‘Iracema’, cuya productividad fue de 38 t ha-1, fueron acumulados 136.0, 93.9, 84.1, 22.6, 15.4 y 9.5 kg ha-1 de K, N, Ca, Mg, S y P, respectivamente. En relación al total acumulado, las exportaciones de N, P, K, Ca, Mg y S en los frutos fueron de 61, 73, 66, 9, 35 y 39% (‘Olimpic express’)y 58, 70, 55, 6, 33 y 41% (‘Iracema’). Con una menor producción de frutos y una mayor acumulación de nutrientes, ‘Olimpic express’ ha demostrado ser menos eficiente en el uso de nutrientes que ‘Iracema’.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Agronomia - FEIS
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Pós-graduação em Agronomia (Agricultura) - FCA
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Pós-graduação em Ciência e Tecnologia Animal - FEIS
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Zootecnia - FMVZ
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Pós-graduação em Zootecnia - FMVZ
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)