Crescimento e nutrição mineral de capim-braquiária
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Data
2005-09-01
Autores
Bianco, S. [UNESP]
Tonhão, M.A.R. [UNESP]
Pitelli, R.A. [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira da Ciência das Plantas Daninhas
Resumo
Brachiaria decumbens, vulgarmente conhecida por capim-braquiária, é considerada uma importante planta daninha, muito agressiva e de difícil controle em áreas onde foi introduzida como forrageira e posteriormente tornou-se lavoura. Com o objetivo de estudar a produção de massa seca, a distribuição e o acúmulo de macronutrientes em plantas de capim-braquiária, foi conduzido o presente trabalho em casa de vegetação. As plantas foram cultivadas em vasos preenchidos com areia de rio lavada e peneiradas e irrigadas diariamente com solução nutritiva completa de Hoagland & Arnon a 50% da concentração original. A primeira avaliação foi realizada aos 20 dias após a emergência (DAE), e as seguintes, em intervalos de 14 dias. Foi determinada a massa seca das diferentes partes da planta. O material foi moído e analisado quanto aos teores de macronutrientes. Os resultados indicaram que a planta apresentou crescimento durante toda a fase experimental. O maior acúmulo ocorreu aos 160 DAE, sendo de 38,27 g planta-1 de massa seca. Aos 160 DAE, cerca de 37,37% da massa seca estava alocada nas raízes, 37,54% nos colmos + bainhas e 25,09% nas folhas. O acúmulo total dos macronutrientes foi crescente até os 146 dias após a emergência. Aos 76 DAE (período de maior competição dessa espécie com a maioria das culturas anuais), uma planta de capim-braquiária acumulou 1,32 grama de massa seca; 40,8 mg de K; 18,2 mg de N; 6,3 mg de Ca; 5,2 mg de Mg; 2,68 mg de P; e 2,4 mg de S.
Brachiaria decumbens, commonly known as surinam grass, is considered an important weed, very aggressive and difficult to control in areas where it was introduced as forage grass and later became a crop. Dry matter production and macronutrient distribution and accumulation in B. decumbens were evaluated under greenhouse conditions. The plants were grown in pots filled with washed and sieved river sand, and irrigated daily with Hoagland & Arnon complete nutrient solution at 50% of the original concentration. The first evaluation was performed 20 days after emergence (DAE) of seedlings and the others every 14 days. Dry matter of every plant part was determined. The material was ground and analyzed for macronutrient content. The results indicated plant growth throughout the experimental phase. The largest accumulation occurred at 160 DAE, when the plant accumulated 38.27 grams of dry mass. At 160 DAE, around 37.37% of the dry biomass was accumulated in the roots, 37.54% in the stems and sheath and 25.09% in the leaves. Total macronutrient accumulation increased up to 146 days after emergence. At 76 DAE ( period of greater competition between the weeds and most of the annual cultures), a surinam grass plant accumulated 1.32 grams of dry mass; 40.8 mg of K; 18.2 mg of N; 6.3 mg of Ca; 5.2 mg of Mg; 2.68 mg of P and 2.4 mg of S.
Brachiaria decumbens, commonly known as surinam grass, is considered an important weed, very aggressive and difficult to control in areas where it was introduced as forage grass and later became a crop. Dry matter production and macronutrient distribution and accumulation in B. decumbens were evaluated under greenhouse conditions. The plants were grown in pots filled with washed and sieved river sand, and irrigated daily with Hoagland & Arnon complete nutrient solution at 50% of the original concentration. The first evaluation was performed 20 days after emergence (DAE) of seedlings and the others every 14 days. Dry matter of every plant part was determined. The material was ground and analyzed for macronutrient content. The results indicated plant growth throughout the experimental phase. The largest accumulation occurred at 160 DAE, when the plant accumulated 38.27 grams of dry mass. At 160 DAE, around 37.37% of the dry biomass was accumulated in the roots, 37.54% in the stems and sheath and 25.09% in the leaves. Total macronutrient accumulation increased up to 146 days after emergence. At 76 DAE ( period of greater competition between the weeds and most of the annual cultures), a surinam grass plant accumulated 1.32 grams of dry mass; 40.8 mg of K; 18.2 mg of N; 6.3 mg of Ca; 5.2 mg of Mg; 2.68 mg of P and 2.4 mg of S.
Descrição
Palavras-chave
Weeds, B. decumbens, Macronutrients, Plantas daninhas, Brachiaria decumbens, Macronutrientes
Como citar
Planta Daninha. Sociedade Brasileira da Ciência das Plantas Daninhas , v. 23, n. 3, p. 423-428, 2005.