Efeitos fisiológicos e bioquímicos do estresse salino em Ananas porteanus Hort Veitch ex C. Koch

Abstract

The ornamental species are standing out in the brazilian agribusiness and among them is the Ananas porteanus, the ornamental pineapple. The brazilian northwest, a region with a tendency to salinization, is a large producer of ornamental tropical plants. Studies on these plants' tolerance under saline conditions are important to usage on already salinized areas or in process of salinization. A. porteanus plants were cultivated during 90 days in sand washed and irrigated with a nutritive solution with 80,0 mM of NaCl or without this salt, constituting two treatments. Growth variables, Na+, Cl- and K+ levels, total soluble proteins, total soluble carbohydrates, proline, total phenols, peroxidase activity and cellular membrane damage were observed. The saline treatment reduced biomass production that was associated with increase in Cl- (230%) and Na+ (39%) levels and to reduction in K+ (38%) levels in the shoot. In parallel it was observed a reduction in soluble carbohydrate levels while the proline levels were six times higher than control. In saline conditions the peroxidase activity (POD) was doubled and the phenols levels, which are oxidized by POD, decreased. These factors associated to proline increase were important for not allowing the membrane to reach 20% damage. The levels of chlorophyll increased 15% pointing to a photosynthetic apparatus protector role.