nitrate and ammonium ions are the two major forms of nitrogen that taken up by plants, but they differ in their effects on growth and chemical composition of biochemical levels. in this research we examined the effect of nitrogen sources on growth and senescence of rice leaves in biochemical levels. our results showed that amounts of fresh and dry weights, total chlorophyll, rate of hill,s reac...

Silicon (Si) is important in mitigating abiotic and biotic plant stresses, yet many agricultural soils, such as those of the rainfed production areas of the South African sugar industry, are deficient in plant-available Si, making Si supplementation necessary. However, Si uptake by sugarcane (Saccharum spp. hybrids) is limited even where silicate amendments improve soil Si status. Rhizosphere p...

Atrazine, metolachlor, carbaryl, and chlorothalonil are detected in streams throughout the U.S. at concentrations that may have adverse effects on benthic microbes. Sediment samples were exposed to these pesticides to quantify responses of ammonium, nitrate, and phosphate uptake by the benthic microbial community. Control uptake rates of sediments had net remineralization of nitrate (-1.58 NO3 ...

Plants take up inorganic nitrogen (N) primarily as nitrate but also to a lesser extent as ammonium. Nitrate is reduced to nitrite in the cytoplasm by the highly regulated enzyme nitrate reductase. Nitrite is transported into the chloroplast and further reduced by nitrite reductase to ammonium. Ammonium is assimilated into the amino acid pool by the coordinate action of Gln synthetase (GS) and G...

The development of titrimetric sensor applications to monitor biological wastewater treatment processes is shortly described, and the measurement principle (based on a pH controller) is illustrated. 3 applications that were developed during the past years are used to illustrate the capabilities of titrimetric sensors. The ammonium and the nitrate concentration can be measured to monitor the nit...

Excised 7-day-old oat (Avena sativa L. cv. Jaycee) leaves were incubated in media containing 7.1 millimolar KNO(3) and 0.15 millimolar tabtoxin or 1 millimolar methionine sulfoximine (MSO) to investigate the sources of the observed ammonium accumulated. Tabtoxin and MSO are known inhibitors of glutamine synthetase, the first enzyme in the primary pathway of ammonium assimilation. During a 4- to...

The specific activities of nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthase, and glutamate dehydrogenase were determined in intact protoplasts and intact chloroplasts from Chlamydomonas reinhardtii. After correction for contamination, the data were used to calculate the portion of each enzyme in the algal chloroplast. The chloroplast of C. reinhardtii contained all...

An adjuvant composition containing a) one or more alkyl glucamides of the formula (I), wherein R1 represents a linear or branched alkyl group having 5 to 9 carbon atoms, R2 represents an alkyl group having 1 to 3 carbon atoms; b) at least one water-soluble ammonium salt, preferably selected from the group consisting of ammonium sulfate, ammonium nitrate, ammonium nitrate urea, ammonium phosphat...