NITROGEN NUTRITION, YIELD AND QUALITY OF SPINACH

When grown in solution culture spinach plants confirmed the preference toward NO; nutrition and showed heavy toxicity to NH4+. In open field condition the highest yield was achieved with the ammonium sulphate i n Bari (autumn-winter cycle-110 days) and with calcium nitrate in Poli coro (winter-spring cycle-64 days). By increasing N level, yield, nitr ates and oxalates leaf content increased. Oxalate content was not affe cted by nitrogen form. Remarkable differences were observed between le af petiole and blade in nitrate (4062 vs 925 mg kg(-1) of fresh mass) and oxalate (1051 vs 6999 mg kg(-1) of fresh mass). (C) 1998 SCI.