Produtividade, acúmulo de nitrato e estado nutricional de cultivares de alface, em hidroponia, em função de fontes de nutrientes
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2002-01-29
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Horticultura Brasileira
Resumo
Foram avaliados a produtividade, acúmulo de nitrato e estado nutricional das cultivares de alface Regina, Babá de Verão e Grandes Lagos em cultivo hidropônico. O experimento foi conduzido no outono, de 25/03 a 20/05/99 em estufa da UFV. Foram avaliados dois conjuntos de fontes de nutrientes para compor as soluções nutritivas de crescimento vegetativo, que continham: 13,6; 1,0; 7,0; 4,48; e 2,5 mmol L-1 de N, P, K, Ca e Mg, respectivamente. O enxofre foi fornecido na concentração de 3,5 ou 2,5 mmol L-1 e os micronutrientes nas concentrações de 45; 32; 46; 2; 0,9; e 0,2 mmol L-1 para Fe, Mn, B, Zn, Cu e Mo, respectivamente. A solução 1 forneceu 21,9% de N na forma amoniacal, e a solução 2, 100% de N na forma de nitrato. As fontes de P empregadas foram fosfato monoamônico e fosfato monopotássico para as soluções 1 e 2 respectivamente, sendo que esta variação implicou no uso de diferentes quantidades de KCl nas soluções, o que proporcionou concentrações diferentes de Cl, apresentando-se 6,76 e 2,18 mmol L-1 para as soluções 1 e 2, respectivamente. O cultivo foi feito em recipiente plástico com 8L de capacidade, contendo três plantas. Os recipientes foram arranjados de modo que se obtivesse espaçamento de 0,22 m entre plantas. O delineamento experimental utilizado foi blocos ao acaso com seis repetições, em arranjo fatorial 2 x 3 (soluções x cultivares). Cada parcela foi constituída por três plantas. Foram avaliados o peso da matéria fresca da parte aérea, folhas, raízes e caule, número de folhas, comprimento do caule, porcentagem de matéria seca das folhas e estado nutricional da planta. A cv. Regina produziu 233 g planta-1 e a cv. Babá de Verão 193 g planta-1. Os resultados obtidos para a cultivar Grandes Lagos não foram satisfatórios nas condições do experimento. A solução 1 proporcionou menores concentrações de nitrato para as cultivares Grandes Lagos (1082 mg kg-1 de matéria fresca) e Regina (1092 mg kg-1 de matéria fresca). As plantas apresentaram altas concentrações de Mn, mas sem sintomas de toxidez. Em geral, a nutrição das plantas foi adequada para os dois conjuntos de fontes de nutrientes testados.
The yield, nitrate concentration and nutritional status of the lettuce cvs. Regina, Babá de Verão and Great Lakes cultivated in hydroponic system were evaluated. The experiment was carried out in fall from March to June/99 in a greenhouse of the Universidade Federal de Viçosa, Brazil. Two groups of nutrient sources were evaluated to compose the nutritive solutions. The solutions were composed of 13.6; 1; 7; 4.48; and 2.5 mmol L-1 of N, P, K, Ca and Mg, respectively. The sulfur contents were 3.5 or 2.5 mmol L-1 and micronutrient contents were 45; 32; 46; 2; 0.9; and 0.2 mmol L-1 of Fe, Mn, B, Zn, Cu and Mo, respectively. The solution 1 supplied 21,9% of N-NH4+, and the solution 2, 100% of N-NO3. The phosphorus sources employed were NH4H2PO4 and KH2PO4 for the solutions 1 and 2, respectively, and this variation implied in the use of different amounts of KCl in the solutions, providing different concentrations of Cl of 6.76 and 2.18 mmol L-1 for the solutions 1 and 2, respectively. Lettuce plants were grown in plastic recipient with 8 L of capacity. The recipients containing three plants were arranged to obtain spacing of 0.22 m between plants. A randomized block design in a 2 x 3 (solutions x cultivars) factorial scheme, with six replications and three plants per plot was used. The fresh matter of shoots, leaves, roots and stems, number of leaves, stem length, leaves dry matter and plant nutricional status were evaluated. The yield of cv. Regina was 233 g plant-1 and of cv. Babá de Verão was 193 g plant-1. The cv. Great Lakes presented low yield. The solution 1 provided smaller nitrate concentrations for Great Lakes (1082 mg kg-1 in fresh matter) and Regina (1092 mg kg-1 in fresh matter). The plants presented high concentrations of Mn, but without toxic symptoms. The plant nutritional status was satisfactory.
The yield, nitrate concentration and nutritional status of the lettuce cvs. Regina, Babá de Verão and Great Lakes cultivated in hydroponic system were evaluated. The experiment was carried out in fall from March to June/99 in a greenhouse of the Universidade Federal de Viçosa, Brazil. Two groups of nutrient sources were evaluated to compose the nutritive solutions. The solutions were composed of 13.6; 1; 7; 4.48; and 2.5 mmol L-1 of N, P, K, Ca and Mg, respectively. The sulfur contents were 3.5 or 2.5 mmol L-1 and micronutrient contents were 45; 32; 46; 2; 0.9; and 0.2 mmol L-1 of Fe, Mn, B, Zn, Cu and Mo, respectively. The solution 1 supplied 21,9% of N-NH4+, and the solution 2, 100% of N-NO3. The phosphorus sources employed were NH4H2PO4 and KH2PO4 for the solutions 1 and 2, respectively, and this variation implied in the use of different amounts of KCl in the solutions, providing different concentrations of Cl of 6.76 and 2.18 mmol L-1 for the solutions 1 and 2, respectively. Lettuce plants were grown in plastic recipient with 8 L of capacity. The recipients containing three plants were arranged to obtain spacing of 0.22 m between plants. A randomized block design in a 2 x 3 (solutions x cultivars) factorial scheme, with six replications and three plants per plot was used. The fresh matter of shoots, leaves, roots and stems, number of leaves, stem length, leaves dry matter and plant nutricional status were evaluated. The yield of cv. Regina was 233 g plant-1 and of cv. Babá de Verão was 193 g plant-1. The cv. Great Lakes presented low yield. The solution 1 provided smaller nitrate concentrations for Great Lakes (1082 mg kg-1 in fresh matter) and Regina (1092 mg kg-1 in fresh matter). The plants presented high concentrations of Mn, but without toxic symptoms. The plant nutritional status was satisfactory.
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Lactuca sativa L., Soluções nutritivas, Nutrição mineral, Cultivo sem solo.