10 research outputs found
Nitrogênio e enxofre nas características morfogênicas do capim-marandu em substituição ao capim-braquiária em degradação em solo com baixo teor de matéria orgânica
Nitrogênio e enxofre na adubação e em folhas diagnósticas e raízes do capimbraquiária em degradação
Yield, chemical composition and chlorophyll relative content of Tanzania and Mombaça grasses irrigated and fertilized with nitrogen after corn intercropping
Macronutrientes em folhas diagnósticas do capim-tanzânia adubado com nitrogênio e cálcio Macronutrients concentrations in Tanzania guineagrass diagnostic leaves supplied with nitrogen and calcium rates
Um experimento foi realizado em casa de vegetação com capim-tanzânia adubado com combinações de nitrogênio e de cálcio em solução nutritiva no período da primavera. O delineamento estatístico foi de blocos ao acaso, com quatro repetições, em esquema fatorial 5² incompleto, com cinco doses de nitrogênio (2; 9; 16; 23 e 30 mmol L-1) e cinco de cálcio (0,50; 1,75; 3,00; 4,25 e 5,50 mmol L-1), resultando em 13 combinações nitrogênio:cálcio (mmol L-1): 2:0,50; 2:3,00; 2:5,50; 9:1,75; 9:4,25; 16:0,50; 16:3,00; 16:5,50; 23:1,75; 23:4,25; 30:0,50; 30:3,00 e 30:5,50. Foram determinadas as concentrações dos macronutrientes nas lâminas de folhas recém-expandidas (diagnósticas) nos três cortes do capim. No primeiro corte das plantas, a dose de cálcio não interagiu com a de nitrogênio para qualquer característica nutricional, à exceção da concentração de enxofre nas folhas. A interação nitrogênio × cálcio foi significativa para as concentrações de cálcio e enxofre nas folhas no segundo e terceiro cortes do capim. As doses de nitrogênio, e não de cálcio, são determinantes das concentrações de nitrogênio, fósforo e potássio em folhas de capim-tanzânia. A concentração de cálcio no primeiro corte do capim depende apenas do suprimento desse nutriente. A concentração de magnésio no tecido vegetal decresce com o aumento no suprimento, tanto de nitrogênio quanto de cálcio. A redução da dose de cálcio para 40% daquela empregada na solução não prejudica os parâmetros nutricionais do capim-tanzânia, mesmo quando fornecidas elevadas doses de nitrogênio.<br>An experiment under greenhouse conditions was carried out with Tanzania guineagrass supplied with combined rates of nitrogen and calcium in nutrient solutions during the spring season. A randomized block design was used, with four replicates, in an incomplete 5² factorial scheme with five nitrogen rates (2; 9; 16; 23 e 30 mmol L-1) and five calcium rates (0.50; 1.75; 3.00; 4.25 e 5.50 mmol L-1) resulting in 13 nitrogen:calcium combinations (mmol L-1): 2:0.50; 2:3.00; 2:5.50; 9:1.75; 9:4.25; 16:0.50; 16:3.00; 16:5.50; 23:1.75; 23:4.25; 30:0.50; 30:3.00 and 30:5.50. Macronutrient concentrations were determined in the two recently expanded leaf blades (diagnostic leaves) collected in the three harvests of Tanzania guineagrass. The results showed that, in the first harvest of the plants, calcium rates did not interact with nitrogen for any of the nutritional traits, except for sulphur concentration in the diagnostic leaves. The interaction nitrogen × calcium was significant for concentrations of calcium and sulphur in the diagnostic leaves at the second and third samplings of the grass. Nitrogen rates and, not calcium rates, are determinant for nitrogen, phosphorus, and potassium concentrations in the diagnostic leaves of Tanzania guineagrass. The concentration of calcium at the first harvest of the grass depends only on the supply of this nutrient. Concentration of magnesium in plant tissue decreases as nitrogen or calcium supply increases. Reduction of calcium to 40% of that one used in the nutrient solution does not reduce nutritional parameters of this grass, even with the supply of high nitrogen rate
Root system characteristics of Marandu palisadegrass supplied with nitrogen and magnesium rates
The development of root system of forage grasses is influenced by the supply of mineral nutrients. The experiment was carried out in a greenhouse in Piracicaba, São Paulo State, with the objective of evaluating the effect of nitrogen and magnesium rates on dry mass yield, total length and surface, specific length and surface, and concentrations of nitrogen, magnesium, calcium and potassium in the root system of Brachiaria brizantha Stapf. cv. Marandu. It was studied five rates of nitrogen (2, 9, 16, 23 and 30 mmol L-1) and five rates of magnesium (0.05, 0.70, 1.35, 2.00 and 2.65 mmol L-1) in nutrient solutions in an incomplete 5² factorial arrangement, which resulted in the following combinations: 2/0.05; 2/1.35; 2/2.65; 9/0.70; 9/2.00; 16/0.05; 16/1.35; 16/2.65; 23/0.70; 23/2.00; 30/0.05; 30/1.35 and 30/2.65. The experimental design was a randomized block with four replications. Plants had two growth periods, and after the second harvest the roots were separated from the plant tops. Combination of the high rates of nitrogen and magnesium resulted in expressive increases in rooty dry matter yield, in the length and in the root surface of marandu palisadegrass. High rates of nitrogen and magnesium resulted in short root specific length and surface. Combinations of high rates of nitrogen and magnesium increased nitrogen concentration or decreased potassium concentration in the roots. Calcium concentration in the roots was increased by nitrogen rates and decreased by magnesium rates. Magnesium rates resulted in increase in magnesium concentration in the roots of marandu palisadegrass