Abstract
Like other abiotic stresses, boron (B) toxicity is an important environmental constraint that limits crop productivity worldwide. B toxicity alters many physiological processes necessary for plant survival. The aim of the present study was to investigate the individual and combined effects of calcium (Ca) and B on morphological and physiological attributes of radish (Raphanus sativus L.) under normal and boron-toxicity conditions. The application of 30 mM Ca and 0.5 mM B, alone and in combination, enhanced plant growth, physiological and biochemical attributes. However, 5 mM B was detrimental to most growth and physiological parameters. The application of 30 mM Ca was most effective in alleviating the harmful effects of B toxicity by decreasing malondialdehyde and hydrogen peroxide levels and electrolyte leakage and by enhancing the activities of the antioxidant enzymes superoxide dismutase, catalase, peroxidase, glutathione reductase, and ascorbate peroxidase. Ca clearly induced plant protection mechanisms by enhancing the accumulation of proline, total soluble carbohydrates, and photosynthetic pigments in leaves.