The purpose of this study was to characterize the effect of temperature on the distribution of Na+, Cl- and K+ in roots, stems and leaves of cowpea pre-treated with NaCl. After the acclimation period, plants were divided into two groups: 0 NaCl and 100 mM NaCl for 2 days. Subsequently, the plants were divided into 4 sub-groups and subjected to increasing temperatures of 27, 32, 37 and 42 ºC, separately, for a photoperiod of 12 hours at each temperature. The treatment without NaCl at 27 ºC was used as reference. The concentrations of Na+ and Cl- in different organs were increased by pretreatment with NaCl and this accumulation was intensified by exposure to high temperatures. In roots, for example, at temperature of 42 ºC concentrations of Na were four times higher than in leaves. While Cl- accumulated mainly in leaves, with a 20-fold increase in the concentration of this ion in relation to reference plants. Inversely, K+ concentrations were reduced in all organs analyzed. Thus, it is conclude that high temperatures affect the distribution of ions in different organs directly affecting ion homeostasis in plants.
Vigna unguiculata; salt stress; heat
