The effect of growing spinach (Sypinacia oleracea L.) at two light intensities on the amounts of oxalate, ascorbate and nitrate in their leaves

The effect of growing spinach at two light intensities on the content of oxalate, ascorbate and nitrate in their leaves was determined. Plants were grown for five weeks in a growth cabinet under a 10 h light/14 h dark photoperiod and a photon flux density of either 800 or 200 mumol quanta m(-2) s(-1). The content of oxalate, ascorbate and nitrate in the fourth and fifth fully expanded true leaves was then determined at three times during the photoperiod. Spinach plants grown at the lower light intensity showed decreased growth, a decreased leaf area per plant and an increased shoot to root ratio. Leaves from plants grown under low light contained less ascorbate but more oxalate and nitrate. Our data show that the nutritional quality of spinach is thereby decreased by growth in low light intensities and suggest that the content of oxalic acid in leaves may depend on the rate of its catabolism.