Oxidant and antioxidant compounds, gas exchange and growth of young Schizolobium parahyba var. amazonicum plants under high boron and calcium concentrations

Boron (B) and Calcium (Ca) unbalance in plants during early stages can generate oxidative stress and consequently to interfere negatively on growth and quality of seedlings. This study aims to evaluate the gas exchange and measure the biochemical responses, responding how high concentrations of B and Ca can affect the growth and quality of young Schizolobium parahyba plants. The experimental design used was completely randomised with four treatments [1 - 25 µM B + 5 mM Ca (control); 2 - 25 µM B + 50 mM Ca (Ca high); 3- 250 µM B + 5 mM Ca (B high) and 4 - 250 µM B + 50 mM Ca (B and Ca high)]. Negative impacts on gas exchange, photosynthetic pigments and total glutathione were obtained, besides increases in hydrogen peroxide and electrolyte leakage were verified in plants treated with B and Ca high, indicating oxidative stress. Thus, application 250 µM B combined with 50 mM Ca promoted disorders in plant metabolism, decreasing the growth and quality of young Schizolobium parahyba plants.