THE INFLUENCE OF NITRATE/AMMONIUM RATIO ON YIELD QUALITY AND NITRATE, OXALATE AND VITAMIN C CONTENT OF BABY LEAF SPINACH AND BLADDER CAMPION PLANTS GROWN IN A FLOATING SYSTEM
Spinach (Spinacia oleracea) is a much valued vegetable, widely consumed everywhere because it is a healthy product and contains relatively high concentrations of nutritional compounds, such as vitamin A, B and C as well as minerals such as iron and magnesium. Bladder campion (Silene vulgaris) is very much appreciable in the traditional gastronomy of several European countries. High amounts of polyunsaturated fatty acids have been recently found across populations of this species. In contrast, some levels of harmful components for human health (nitrates and oxalates) have been found in leafy vegetables. The floating system is an easy and profitable growing technique for the cultivation of small-sized vegetable crops. In this hydroponic system the optimum management of the nutrient solution could reduce the nitrate and oxalate concentration. The objective of this work was to analyze the effect of several nitrate/ammonium ratios on yield quality and nitrate, oxalate and vitamin C content in baby leaf spinach and bladder campion grown in a floating system. Seeds were sown directly into stryrofloat trays containing commercial substrate media. The duration of the crop cycles were 34 and 43 days for spinach and bladder campion, respectively. The nutrient solution contained 12 μmolL-1 of N and the following nitrate/ammonium ratios: 100/0, 75/25, 50/50 and 25/75 were tested. The best yield and the high vitamin C content were found with 75/25 ratio in both species. The highest nitrate and oxalate contents were found when the 100/0 NO3-/NH4+ ratio was used for both species. The substitution of N-nitrate by N-ammonium in the nutrient solution caused a reduction of the nitrate and the oxalate content in both spinach and bladder campion leaves.
Conesa, E., Niñirola, D., Vicente, M.J., Ochoa, J., Bañón, S. and Fernández, J.A. (2009). THE INFLUENCE OF NITRATE/AMMONIUM RATIO ON YIELD QUALITY AND NITRATE, OXALATE AND VITAMIN C CONTENT OF BABY LEAF SPINACH AND BLADDER CAMPION PLANTS GROWN IN A FLOATING SYSTEM. Acta Hortic. 843, 269-274
Spinacia oleracea, Silene vulgaris, local accession, nutrient solution, NO3-/NH4+ ratio