Cálcio, magnésio e potássio como amenizadores dos efeitos da salinidade sobre a nutrição mineral e o crescimento de mudas de aroeira (Myracrodruon urundeuva)

Abstract

Aroeira (Myracrodruon urundeuva) is a native tree of important socio-economic value but, due to the predatory exploration, it is threatened of extinction, demanding studies that guarantee its survival and plantation in soils not incorporated to the productive system, like soils with salinity problems. To verify the calcium, magnesium and potassium action in reducing salinity effect in aroeira, a greenhouse experiment was conducted. A Hoagland & Arnon nutrient solution at 50% of concentration with NaCl (150 mol m-3) and different concentrations of Ca, Mg and K were used. After 35 days of treatment the plants were harvested and their stem diameter, root, stem and leaf dry matters and accumulated nutrients were evaluated. The addition of 150 mol m-3 of NaCl promoted significant reduction in stem diameter and dry matter of root, stem and leaf, showing aroeira’s high sensibility to salinity. This reduction was less evident in plants that received larger concentration of Ca, which presented a larger accumulation of Ca, Mg and K in its compartments. Plants that received 6 mol m- 3 of K presented Ca/Na, Mg/Na and K/Na ratio of about two times more than those that received other treatments, but approximately three times less than those that did not receive salt, showing the negative effect of NaCl in the absorption of the nutrients. The concentrations of Ca, K and Mg used in this experiment were not enough to prevent the negative effect of the osmotic stress caused by NaCl in the growth of the aroeira.