Nitrato modula os teores de cloreto e compostos nitrogenados em plantas de milho submetidas à salinidade

Abstract

This work aimed to study the effect of nitrate (NO-3) on growth and accumulation of inorganic and organic solutes in maize plants subjected to salinity. The experiment was carried out in a completely randomized design, with five replications, and a 2×4 factorial scheme, consisting of eight treatments: two salinity levels (NaCl at 0 or 75 mM) and four different concentrations of NO-3 (0.5, 2.5, 5.0 or 7.5 mM) in nutrient solution. The dry mass of shoots and roots was reduced by salinity, however, this was less evident when plants were exposed to concentrations of NO-3 below 2.5 mM. The best growth was observed in the approximate concentration of 5.0 mM NO-3. The Na+ and Cl- contents increased with salinity in all organs studied, and the highest accumulation of these ions was observed in the roots. In general, the K+ content was not severely affected by this stress. With the increase of NO-3 concentration in the medium, there was an improvement in the absorption of this ion, leading to reduced uptake of Cl- and the accumulation of proline and soluble amino acids. Nutritional stress is more limiting to plant growth of maize than the salt stress, with harmful effects being alleviated by an adequate nutrition of NO-3.