Características fisiológicas e crescimento de clones de eucalipto em resposta ao boro
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2009-06-23
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A exigência para boro (B) varia largamente entre e dentro das espécies vegetais. Objetivando avaliar a resposta de clones de eucalipto ao B em solução nutritiva foi realizado ensaio em casa de vegetação com oito clones. As plantas cresceram em soluções nutritivas com 0, 10, 20, 50 e 100 µmol/L de B, durante 70 dias. Na finalização do ensaio determinaram-se características fisiológicas, produção de matéria seca e teores de B no tecido vegetal. Houve resposta diferenciada dos clones à concentração de B na solução nutritiva, com máxima produção de matéria seca entre 28 e 69 µmol/L de B. Em baixas concentrações de B, pôde-se observar sintomas visuais de deficiência e, em altas concentrações, não foram observados sintomas de toxidez, porém houve redução na produção de matéria seca. A resposta do eucalipto ao B na solução nutritiva depende do clone, havendo diferenças entre eles na tolerância à deficiência e toxidez e na eficiência de utilização de B. Os clones 68 e 129 apresentaram as mais elevadas taxas de fotossíntese. O clone 3487 foi o mais responsivo ao B. Os clones 3487, 3336 e 68 foram mais sensíveis à deficiência e os clones 3281 e 1270 os mais tolerantes à deficiência. O clone 2486 foi o mais sensível à toxidez e o clone 3281 o mais tolerante. Os clones 3487, 2486 e 129 foram mais eficientes na utilização de B.
Boron (B) requirement for plant growth varies both within and among plant species. In order to evaluate the response of clones of eucalyptus to B in nutrient solution, an experiment was carried out under glasshouse conditions, with eight clones. Plants were grown in nutrient solutions at B concentrations of 0, 10, 20, 50 and 100 µmol/L for 70 days, after which, physiological variables, dry matter production and boron content were determined. There was a differential response of the eucalyptus clones to the concentration of boron in nutrient solution with maximum dry matter production occurring between 28 and 68 µmol/L of B in nutrient solution. At low concentrations of B, visual symptoms of deficiency were observed. At high B concentrations, toxicity symptoms were not observed; however, there was a reduction in dry matter production. The response to B depends on the clone. The clones 129 and 68 showed the highest rates of photosynthesis. The clone 3487 was the most responsive to B. The clones 3487, 3336 and 68 were more sensitive to B deficiency whereas clones 3281 and 1270 exhibited greater tolerance to B deficiency. Clone 2486 was the most sensitive to B toxicity and the clone 3281 showed the highest tolerance to B. Clones 3487, 2486 and 129 were more efficient in the use of boron.
Boron (B) requirement for plant growth varies both within and among plant species. In order to evaluate the response of clones of eucalyptus to B in nutrient solution, an experiment was carried out under glasshouse conditions, with eight clones. Plants were grown in nutrient solutions at B concentrations of 0, 10, 20, 50 and 100 µmol/L for 70 days, after which, physiological variables, dry matter production and boron content were determined. There was a differential response of the eucalyptus clones to the concentration of boron in nutrient solution with maximum dry matter production occurring between 28 and 68 µmol/L of B in nutrient solution. At low concentrations of B, visual symptoms of deficiency were observed. At high B concentrations, toxicity symptoms were not observed; however, there was a reduction in dry matter production. The response to B depends on the clone. The clones 129 and 68 showed the highest rates of photosynthesis. The clone 3487 was the most responsive to B. The clones 3487, 3336 and 68 were more sensitive to B deficiency whereas clones 3281 and 1270 exhibited greater tolerance to B deficiency. Clone 2486 was the most sensitive to B toxicity and the clone 3281 showed the highest tolerance to B. Clones 3487, 2486 and 129 were more efficient in the use of boron.
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Eucalyptus sp., Deficiência e CUB