BORON AND MANGANESE INFLUENCE ON GROWTH AND MINERAL COMPOSITION ON YOUNG GUAVA PLANTS

Two experiments were carried out in nutrient solution in order to evaluate the effects of boron and manganese on growth and mineral composition of young guava seedling (Psidium guajava L.). The treatments with boron consisted of seven levels: 0, 0.125, 0.25, 0.5, 1.0, 1.5 and 3.0 mg L-1. Tip and marginal necrosis, and purple circular spots on the blade were the main observed symptoms associated with leaf boron concentration of 146 mg kg(-1). Analysis of leaf tissues with and without necrosis showed boron content of 92 and 720 mg kg(-1), respectively. Boron levels affected only dry matter roots, phosphorus, and sulfur concentration. The experiment with manganese used of seven levels: 0.0, 0.50, 10.0, 20.0, 30.0, 40.0 e 50.0 mg L-1. Total dry matter production, Ca, Mg and Fe contents were affected by manganese. The toxicity symptoms became evident as dense sprinkles of minuscule dark spots in old leaves; young leaves of reduced size, chlorotic and green reticulate in the veins; formation of circular brown, and punctuations spread along or between the veins.