PHYSIOLOGICAL AND BIOCHEMICAL MECHANISMS OF ORNAMENTAL PINEAPPLE UNDER SALT STRESS

The bromeliads are hardy plants with exotic beauty, appreciated by consumers worldwide. The species Ananas porteanus Hort ex C. Veitch Koch, in particular, shows great potential for floriculture. These plants acclimate easily to adverse environmental conditions like those found in semi-arid areas. To assess the salinity tolerance of A. porteanus there were two treatments, one without the addition of NaCl (control) and the other with 80 mmol L-1 NaCl. The experiment lasted 90 days and were evaluated in the shoot: shoot dry matter, chloride, sodium and potassium contents, Na+/K+ rate, proline content, total soluble carbohydrates, total soluble proteins, total phenols, peroxidase activity, levels of chlorophyll "a" and "b" and membrane damage. Plants of A. porteanus treated with sodium chloride were able to maintain the integrity of the membrane at levels similar to those found in control plants and the maintenance of membrane integrity result in part from increased activity of peroxidase. The increase in proline and protein content also appears to be one of the strategies of this species to cope with damage caused by the excess of NaCl as well as the increase in levels of chlorophyll. Soluble carbohydrates are not used to adjust the osmotic potential in plants subjected to 80 mmol L-1 NaCl. The metabolic changes occurring in plants of A. porteanus treated with sodium chloride led to a new homeostasis that resulted in the plant tolerance to salt stress imposed.