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.
Eucalyptus sp.; deficiency; NUE
