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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.)
Author(s) -
Wang H.J.,
Wu L.H.,
Tao Q.N.,
Miller D.D.,
Welch R.M.
Publication year - 2009
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1750-3841.2008.01023.x
Subject(s) - nitrogen , ammonium , brassica , chemistry , nitrate , ammonium nitrate , glutamine , botany , biology , biochemistry , amino acid , organic chemistry
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.