Nitrate Accumulation in Spinach as Influenced by Leaf Type1

Abstract Spinach, Spinacia oleracea , L., cv. America, Heavy Pack, and Hybrid 424 were grown in sand culture with variable NO 3 concentrations from 0.187 to 48 meq/l. The cultivars were representative of savoyed, semisavoyed, and smooth-leaf types, respectively. The plants were harvested when those cultured at 12 and 18 meq NO 3 /l had obtained approximate market maturity. At this time an array of deficiency, sufficiency, and toxicity symptoms were evident. Great differences in NO 3 accumulation and critical NO 3 concentrations occurred among cultivars. Critical NO 3 -N concentrations for the whole leaves of spinach plants were: ‘America’, 0.17%, ‘Heavy Pack’, 0.15%, and ‘Hybrid 424’, 0.045% of their dry weights. Calculations relating spinach consumption and impaired human health suggest that adult health should not be affected even with massive ingestion of spinach.