Glutamine Nitrogen and Ammonium Nitrogen Supplied as a Nitrogen Source Is Not Converted into Nitrate Nitrogen of Plant Tissues of Hydroponically Grown Pak-Choi (Brassica chinensis L.)

• Published in: Journal of food science 2009-03, Vol.74 (2), p.T21-T23
• Main Authors: Wang, H.-J, Wu, L.-H, Tao, Q.-N, Miller, D.D, Welch, R.M
• Format: Article
• Language: English
• Subjects: Ammonia - metabolism; ammonium; ammonium nitrogen; bioaccumulation; Biological and medical sciences; Brassica - metabolism; Brassica - physiology; Brassica rapa subsp. chinensis; chemical concentration; chemical constituents of plants; Flowers & plants; Food industries; Food science; Fundamental and applied biological sciences. Psychology; Germination; glutamine; Glutamine - metabolism; Health hazards; Hydroponics; Kinetics; nitrate accumulation; nitrate concentration; nitrate nitrogen; Nitrates; Nitrates - metabolism; Nitrogen; Nitrogen - metabolism; nitrogen content; nutrient solutions; pak-choi (Brassica chinensis L.); Studies; Vegetables
• ISSN: 0022-1147; 1750-3841
• DOI: 10.1111/j.1750-3841.2008.01023.x

Many vegetables, especially leafy vegetables, accumulate NO⁻₃-N in their edible portions. High nitrate levels in vegetables constitute a health hazard, such as cancers and blue baby syndrome. The aim of this study was to determine if (1) ammonium nitrogen (NH⁺₄-N) and glutamine-nitrogen (Gln-N) absorbed by plant roots is converted into nitrate-nitrogen of pak-choi (Brassica chinensis L.) tissues, and (2) if nitrate-nitrogen (NO⁻₃-N) accumulation and concentration of pak-choi tissues linearly increase with increasing NO⁻₃-N supply when grown in nutrient solution. In experiment 1, 4 different nitrogen treatments (no nitrogen, NH⁺₄-N, Gln-N, and NO⁻₃-N) with equal total N concentrations in treatments with added N were applied under sterile nutrient medium culture conditions. In experiment 2, 5 concentrations of N (from 0 to 48 mM), supplied as NO⁻₃-N in the nutrient solution, were tested. The results showed that Gln-N and NH⁺₄-N added to the nutrient media were not converted into nitrate-nitrogen of plant tissues. Also, NO⁻₃-N accumulation in the pak-choi tissues was the highest when plants were supplied 24 mM NO⁻₃-N in the media. The NO⁻₃-N concentration in plant tissues was quadratically correlated to the NO⁻₃-N concentration supplied in the nutrient solution.