title: Response of potatoes to nitrogen concentrations differ with nitrogen forms.
abstract: Two separate experiments were conducted to investigate plant growth and mineral composition of potatoes (Solanum tuberosum L.) at varied solution concentrations of nitrate (NO3-) and ammonium (NH4+). Each experiment evaluated five nitrogen (N) concentrations of 0.5, 2, 4, 8, and 12 mM, which were maintained with a non-recirculating nutrient film system in controlled environment. Plants were harvested on day 42 with NO3-; and day 35 with NH4+ after transplanting of tissue culture plantlets, and growth measurements were taken as leaf area, tuber number, and dry weights of different parts. With NO3-, plant growth was greatest and similar at 2, 4, and 8 mM of N whereas with NH4+, plant growth was best only at 2 and 4 mM of N. At 12 mM of N, plants exhibited interveinal ammonium toxicity with NH4+ nutrition, but healthy growth appearance with NO3- nutrition. With either N form, total N concentrations in tissues tended to increase with increased N concentrations, and tissue phosphorus (P) concentrations were reduced at 0.5 and 2 mM of N. Tissue concentrations of calcium (Ca), magnesium (Mg), and sulfur (S) changed only slightly at particular N concentrations, yet changed substantially with different N forms. The data indicate that the optimal ranges of N concentrations in both solution and tissues are wider and higher with NO3- than with NH4+ nutrition, and thus a careful control of NH4+ concentrations is necessary to minimize possible ammonium toxicity to potato plants.
authors.affiliation: Key Laboratory of Crop Growth Regulation, Ministry of Agriculture Nanjing Agricultural University, People's Republic of China.
authors.forename: W
authors.initials: W
authors.lastname: Cao
authors.forename: T W
authors.initials: TW
authors.lastname: Tibbitts
mesh_terms: D018533:Biomass; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D008903:Minerals / Q000378:metabolism; D009566:Nitrates / Q000494:pharmacology*; D009584:Nitrogen / Q000494:pharmacology*; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development; D018520:Plant Shoots / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D018547:Plant Stems / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*; D011198:Solanum tuberosum / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism
chemical_list: D003470:Culture Media; D008903:Minerals; D009566:Nitrates; D000644:Quaternary Ammonium Compounds; D009584:Nitrogen