Crescimento e distribuição de Na+, K+ e CI em plantas jovens de algaroba, angico, jurema-preta e leucena em resposta ao estresse salino.

Abstract

Growth and distribution of Na+, K+ and CI in young plants of mesquite, angico, jurema-preta and leucena in response to saline stress. This research was conducted to investigate variations in the model of ion distribution and growth in mesquite (Prosopis juliflora, Benth.), and leucaena (Leucena leucocephaia, Benth.), 30 days old, cultivated for 20 days, and irrigated with Hoaghland and Arnon's nutrient solution with 100 mol -3 of NaCl, in a greenhouse. Salinity significantly affected the production and accumulation of total dry mass in Jurema and leucena plants, while for Algarobeira and Angico plants, this effect was smaller. In the presence of NaCl, the internal concentration of saline ions, in the studied species, was increased, with particular emphasis on the Cl ion. The K+ content described in the roots and was stable in the shoot. The ability, or not, of these plants to regulate the absorption and accumulation of Na+, Cl- and K+ suggests a differential model for k+/Na+ selectivity. Thus, young Leucena plants, with the greatest decrease in dry mass production (60%), exhibited a value of 0.25 for the k+/Na+ ratio in the shoot. On the other hand, for young mesquite plants, where the smallest decreases in dry mass accumulation are registered (15%), the k+/Na+ ratio in the shoot was 1.20. These results suggest that ion transport processes are of crucial importance due to the fact that they are presumably essential for the control of the absorption and intracellular levels of ions and their vacuolar compartmentation under restrictive growth conditions.