Boro em arroz de terras altas cultivado em solução nutritiva
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Data
2009-09-01
Autores
Pavinato, Paulo Sérgio [UNESP]
Aguiar, Alana [UNESP]
Castro, Gustavo Spadotti Amaral [UNESP]
Crusciol, Carlos Alexandre Costa [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Instituto Agronômico de Campinas
Resumo
O objetivo deste trabalho foi avaliar o efeito de doses de boro na produção de matéria seca e nos parâmetros morfológicos das raízes de duas cultivares de arroz de terras altas. O experimento foi desenvolvido de abril a julho de 2004, em casa de vegetação, em Botucatu (SP), empregando-se duas cultivares de arroz - Caiapó e BRS Talento. As plântulas foram obtidas em condições controladas e após cinco dias, transferidas para vasos de plástico com capacidade para 8 L, utilizando areia lavada como suporte, deixando quatro plantas por vaso. Os tratamentos foram: 0,0; 0,5; 1,0; 2,0; 4,0 e 8,0 mg L-1 de B, aplicados via solução nutritiva. O corte foi realizado aos 70 dias após o transplante, sendo coletadas parte aérea e sistema radicular separadamente, determinado suas matérias secas e concentrações de N e B, bem como o comprimento, área superficial e diâmetro médio radicular. Não foi possível obter efeito positivo da aplicação de boro, evidenciando que para a cultura do arroz a dose ótima é a inferior a 0,5 ml L-1 de B. A aplicação de 3,8 e 3,4 mg L-1 de B causou efeitos tóxicos às cultivares Caiapó e Talento respectivamente. O limite de toxicidade para raízes das duas cultivares é a concentração de 2,7 mg L-1 de B. Sob toxicidade severa de B as plantas de arroz reduzem expressivamente o comprimento e aumentam o diâmetro radicular, resultando em menor área de absorção de nutrientes.
The objective of this work was to evaluate the effects of boron rates on dry matter yield and root morphologic parameters of two varieties of upland rice. The experiment was carried out from April to July of 2004, in a greenhouse, in Botucatu, São Paulo State, with two varieties of rice, Caiapó and BRS Talento. The seeds were germinated in a controlled chamber, and five days later, the plants were transplanted in plastic pots of 8 L, being supported by cleaned sand, being kept four plants per pot. The boron rates were 0.0; 0.5; 1.0; 2.0; 4.0 and 8.0 mg of B L-1, applied via nutrient solution. The harvest was accomplished 70 days after planting, being collected separately the shoot and root, and being determined their dry matter and N and B concentrations, as length, surface area and medium diameter of the roots. It was not able to get to the positive effects of boron application, evidencing that, for the rice cropping the optimum rate was lower than 0.5 ml L-1 of B. The application of 3.4 and 3.8 mg L-1 of B caused toxic effects to the Caiapó and Talento cvs., respectively. The toxic limit for the two cvs. roots is the 2.7 mg L-1 of B concentration. Under several boron toxic, the plants of rice reduced drastically the length and increased the radicular diameter, resulting in a smaller absorption nutrients area.
The objective of this work was to evaluate the effects of boron rates on dry matter yield and root morphologic parameters of two varieties of upland rice. The experiment was carried out from April to July of 2004, in a greenhouse, in Botucatu, São Paulo State, with two varieties of rice, Caiapó and BRS Talento. The seeds were germinated in a controlled chamber, and five days later, the plants were transplanted in plastic pots of 8 L, being supported by cleaned sand, being kept four plants per pot. The boron rates were 0.0; 0.5; 1.0; 2.0; 4.0 and 8.0 mg of B L-1, applied via nutrient solution. The harvest was accomplished 70 days after planting, being collected separately the shoot and root, and being determined their dry matter and N and B concentrations, as length, surface area and medium diameter of the roots. It was not able to get to the positive effects of boron application, evidencing that, for the rice cropping the optimum rate was lower than 0.5 ml L-1 of B. The application of 3.4 and 3.8 mg L-1 of B caused toxic effects to the Caiapó and Talento cvs., respectively. The toxic limit for the two cvs. roots is the 2.7 mg L-1 of B concentration. Under several boron toxic, the plants of rice reduced drastically the length and increased the radicular diameter, resulting in a smaller absorption nutrients area.
Descrição
Palavras-chave
Oryza sativa L., doses de boro, nutrição de plantas, produção de matéria seca, Oryza sativa L., boron rates, plant nutrition, dry matter yield
Como citar
Bragantia. Instituto Agronômico de Campinas, v. 68, n. 3, p. 743-751, 2009.