PLANT NITROGEN CHARACTERISTICS OF A SEMI-SALT-TOLERANT ZUCCHINI VARIETY TO SODIUM-CHLORIDE TREATMENTS

Plants of a Zucchini (Cucurbita pepo L. var. Moschata) cultivar consid ered to be semi-salt-tolerant were grown in artificial soil in l-m con tainers under greenhouse conditions with differing supplies of sodium chloride (NaCl) [0 (T-0), 30 (T-1), 60 (T-2) or 120 (T-3)g m(-2) plot( -1)] during the entire growth cycle. These plants were used to determi ne the concentrations of nitrogen (N) forms and fractions, together wi th antagonistic anions in both leaves and fruits. The ammonium (NH4) c oncentration increased and nitrate (NO3) concentration decreased in bo th leaves and fruits, and chloride (Cl) concentration increased while sulphate (SO4) concentration decreased in both leaves and fruits with NaCl treatments. Organic-N concentration in leaves increased according to the soil salinity treatments, while in the fruit there was a sligh t increase at low salinity, although values returned to those of the c ontrol when soil salinity increased. In leaves there was an increase i n proline concentrations when salinity was low. As soil salinity incre ased further, this level then fell slightly. In the fruit skin, howeve r, proline concentration decreased as soil salinity increased. Soluble protein and amino-acid concentrations in the skin of the fruit increa sed when there was a moderate increase in soil salinity from T-0 to T- 1. However, as soil salinity increased further, these concentrations d ecreased and returned to levels near the control. The results of fruit yield showed a positive effect of the NaCl treatments with an enhance ment of commercial and also total fruit yield and a decrease in substa ndard fruit yield.