Effects of KCl and CaCl2 uptake and transport of Na+ in cashew plants exposed to NaCl

Abstract

In the work it was evaluated the effect of the K⁺ and Ca²⁺ on the uptake and transport of Na⁺ and K⁺ in the presence of NaCl. Seeds of dwarf-precocious cashew clone CCP 06 were germinated and cultivated in vermiculite in greenhouse. Seedlings with 8 leaves were transferred to controlled conditions, 25±2 °C, U.R 80%, Photoperiod of 12 h and 240 mmol.m^-2.s^-1. After acclimation for 48h, seedlings were displayed, in a factorial (2x2x2) arrangement and  treated with NaCl (0; 200 mM), KCl (0; 5 mM) and CaCl₂ (0; 3 mM), comprising 8 treatments, for 72 hours in buffered water with HEPES 10 mM, pH 6,0. The NaCl induced significant accumulation of Na⁺ in tissues. The accumulation of this ion in shoots was decreased due to exogenous KCl. Moreover, the treatments that contained NaCl + CaCl₂ had an increase of Na⁺ in relation to treatments that contained only NaCl. The content of K⁺ in roots and stems decreased in the presence of  NaCl, with exception of  treatment with CaCl₂ in roots, and of  treatments with CaCl₂ + KCl and CaCl₂ in stems that presented the same levels of the control plots. In leaves this ion remained unchanged, independent of treatment. The attenuating effect of CaCl₂ was not observed in the absorption and/or transport of Na⁺ for seedlings, in opposition to the results found with the KCl. The purpose was to verify effects of KCl and CaCl₂ exogenous in the uptake and transport of Na⁺ e K⁺ in different parts of seedlings of cashew exposed to NaCl.