G udrun D. Trogisch*, H elm ut Köcher**, and W olfram R. Ullrich* * Institut für Botanik, Technische Hochschule, Schnittspahnstraße 3. D-6100 Darmstadt, Bundesrepublik Deutschland ** Hoechst AG, D-6230 Frankfurt 80. Bundesrepublik Deutschland Z. Naturforsch. 44c, 33 — 38 (1989); received July 13/November 11, 1988 Dedicated to Professor Wilhelm Simonis on the occasion o f his 80th birthday Ammon...

The effect of aqueous versus crystalline sulfatenitrate-ammonium tropospheric particles on global aerosol direct radiative forcing is assessed. A global threedimensional chemical transport model predicts sulfate, nitrate, and ammonium aerosol mass. An aerosol thermodynamics model is called twice, once for the upper side (US) and once for lower side (LS) of the hysteresis loop of particle phase....

Nitrate-grown Azotobacter chroococcum ATCC 4412 cells lack the ability to fix N2. Nitrogenase activity developed after the cells were suspended in a combined nitrogen-free medium and was paralleled by a concomitant decrease in nitrate assimilation capacity. In such treated cells exhibiting transitory nitrate assimilation and N2-fixation capacity, nitrate or nitrite caused a short-term inhibitor...

This study investigated the effects of nitrogen form on root activity and uptake kinetics Camellia oleifera Abel. seedlings, providing a scientific basis for improving use efficiency fertilization in C. production. Taking one-year-old cultivar ‘Xianglin 27’ seedlings as subjects, 8 mmol·L−1 varied forms (NO3−:NH4+ = 0:0, 10:0, 7:3, 5:5, 3:7, 0:10) was applied this treatment conditions to invest...

Cyanide assimilation by the beta-cyanoalanine pathway produces asparagine, aspartate and ammonium, allowing cyanide to serve as alternate or supplemental source of nitrogen. Experiments with wheat and sorghum examined the enrichment of (15)N from cyanide as a function of external cyanide concentration in the presence or absence of nitrate and/or ammonium. Cyanogenic nitrogen became enriched in ...

A monitoring program with a weekly sampling frequency over a 15-month period indicates that urea concentrations above a certain threshold level may trigger the blooms of Alexandrium catenella in Thau lagoon. However, urea concentrations were also sometimes related to ammonium and dissolved organic nitrogen concentrations, indicating that the role of urea may not be a direct one. An original app...

graft polymerization of acrylic acid (aa) and ethyl methacrylate (ema) onto starch (st) were carried out in aqueous solution using ceric ammonium nitrate (can) as redox system under n2 atmosphere. the effect of ph, reaction time, temperature, concentrations of can, st, and monomers on the graft yield was investigated. monomer reactivity was in the following order: aa>ema.the kinetics of the gra...

Microelectrodes for ammonium, oxygen, nitrate, and pH were used to study nitrifying aggregates grown in a fluidized-bed reactor. Local reactant fluxes and distribution of microbial activity could be determined from the microprofiles. The interfacial fluxes of the reactants closely reflected the stoichiometry of bacterial nitrification. Both ammonium consumption and nitrate production were local...

Nitrate reductase inhibitor is usually found in the roots of rice plants (Oryza sativa L. cv MR7), but it was also produced in the shoots of aging plants. The inhibitor was inducible in the shoot of rice seedlings by dark, minus-nitrate or plus-ammonium treatments. There appears to be a general involvement of the inhibitor in the control of nitrate assimilation in the plant.