Combination effect of NaCl salinity and nitrogen form on mineral composition of sunflower plants

The effect of two N-forms (NH4+ and NO3-) and NaCl on pattern of accumulation of some essential inorganic nutrients was examined in sunflower (Helianthus annuus L.) cv. Hisun 33. Eight-day-old plants of were subjected for 21 d to Hoagland's nutrient solution containing 8 mM N as NH4+ or NO3-, and salinized with 0, 60, or 120 mM NaCl. N-form and addition of NaCl to the growth medium had no significant effect on total, leaf N. However, root N of NH4-supplied plants decreased significantly with increase in NaCl concentration, whereas that of NO3-supplied plants remained unaffected. There was no significant effect of NaCl on leaf or root P, but the NO3-supplied plants had significantly lower concentration of leaf P than that of NH4-supplied plants at varying salt treatments. Salinity of the rooting medium also did not show any significant effect on Na+ concentrations of leaves or roots of plants subjected to two different forms of N. NH4-treated plants generally had greater concentrations of Cl- in leaves and roots and lower K+ content in leaves than NO3-supplied plants. Ca2+ concentrations of leaves and roots and Mg2+ concentrations of leaves decreased in NH4-supplied plants due to NaCl, but they remained unaffected in NO3-treated plants.