Abstract: A hydroponic experiment was carried out to study effects of different ammonium /nitrate ratios on content and distribution of nitrate and oxalate in sp inach. The results showed that biomass increased with increased ammonium p roportion firstly, then decreased obviously and sp inach had the highest biomass as ammonium /nitrate ratioswere 25 /75 and 50 /50. Nitrate content of different tissues decreased markedlywith ammonium proportion increasing. Total oxalate and soluble oxalate content of leaf decreased obviously in response to elevating ammonium proportion, while oxalate content of petiole and lateral root was the lowest as ammonium /nitrate ratio was 50 /50, oxalate content of tap root decreased with increasing ammonium proportion, too. Distribution of oxalate in different tissues of spinach was uneven, and decreased in the following order: leaf >tap root > petiole > lateral root, and oxalate content of leafwas far higher than that of other tissues. Soluble oxalate was predominant form of oxalate in spinach, which occupied up to more than 69% of total oxalate in the other treatments except that soluble oxalate constituted 38% of total oxalate in leaves as ammonium is sole nitrogen resource. Therefore, ammonium /nitrate ratios of 25 /75 and 50 /50 are benefit for growth of spinach and can reduce soluble oxalate and total oxalate content in sp inach.

Key words: Spinach, Ammonium nitrate ratio, Biomass, Nitrate, Total oxalate, Soluble oxalate