the effects of different levels of nitrogen (100, 200, 300 and 400 mg/l) and potassium (125, 250 and 375 mg/l) on yield and leaf n and k concentrations of tomato were investigated in perlit culture using a factorial randomized design with three replications. the highest fruit yield was obtained with 200 mg/l n. higher levels of nitrogen decreased tomato yield. with increasing nitrogen concentra...

: in order to study the effect of different nitrogen levels on yield components and seed yield of three barley cultivars, an experiment was conducted in 2011-2012 in a research farm of farming building of islamic azad university khorasgan (isfahan) branch located in khatunabad village (latitude 32o /40' n and longitude 51o /48' e). a split plot layout within randomized complete block design wit...

nitrogen is one of the most limiting nutrients for cereal production in many parts of iran. the effects of crop residue incorporation [0 (control), 25 and 50% of wheat (triticum aestivum l.)] and nitrogen (n) levels (0, 150, and 300 kg ha-1) on corn (zea mays l.) grain yield and nitrogen use efficiency were investigated at agricultural research station, shiraz university, shiraz, iran for two y...

-l. Nitrogen and cation excretion/storage in 23 cockroach species representing I l subfamilies have been examined. Measurements of externally excreted ammonia nitrogen, uric acid nitrogen, total nitrogen, potassium and sodium were made. Values of total body nitrogen, body urate nitrogen, and body potassium and sodium are also reported. 2. A significant correlation was found between body nitroge...

Evidence from an international survey in the Atlantic biogeographic region of Europe indicates that chronic nitrogen deposition is reducing plant species richness in acid grasslands. Across the deposition gradient in this region (2-44 kg N ha(-1) yr(-1)) species richness showed a curvilinear response, with greatest reductions in species richness when deposition increased from low levels. This h...

the amount of nitrogen fertilizer is an effective factor on the growth, development, and reproduction of phytophagous insects. to investigate the effect of nitrogen fertilization on intrinsic rate of increase of cabbage aphid, brevicoryne brassicae l., plants rape oilseed (rgs003cultivar) were treated with four nitrogen levels (zero (check) 50, 100, and 150% of recommended levels. the results s...

Nitrogen absorption from the large intestine, largely as ammonia and possibly as amino acids (AAs), is generally thought to be of little nutritional value to nonruminant animals and humans. Ammonia-nitrogen absorbed from the large intestine, however, may be recycled into the small intestine as urea and incorporated into microbial AAs, whichmay then be used by the host. A cecal infusion study wa...

in order to study the effect of nitrogen on competition between wild oat (avena fatua) and wheat (triticum aestivum) at vegetative growth stage, a factorial experiment was conducted based on completely randomized block design with three replications in research greenhouse of faculty of agriculture, at ferdowsi university of mashhad in 2008. first factor was five densities (0, 2, 4, 6 and 8 plan...