one of the main problems in crop production in iran is the difference between actual yield and attainable yield which is called yield gap. thus, identifying yield constraints and yield gap are important. to do this, a study was conducted in 95 farms gorgan of in five villages, during two years 2007 and 2008. in this study, all of the information about management operations, soil and crop charac...

Understanding salinity and fertilizer interaction is of great importance to improve crop production use efficiency in saline areas. To evaluate the interactive effects different soil levels nitrogen (N) applications rates on sunflower photosynthetic characteristics N uptake efficiency, a two-year field experiment was conducted Hetao Irrigation District, China. The consisted three initial (IS) e...

The role of algal size as a controlling factor for nltrogen uptake kinetics is examined by comparing published values of N uptake rate and half-saturation constants in microand macroalgae. The uptake kinetics differ substantially among algae very different in size. Microalgae take up nitrogen much faster per unit of biomass than macroalgae at both high and low substrate concentrations, and micr...

Chlamydomonas reinhardtii possesses a high affinity, highly specific carrier involved in uptake of exogenous arginine. Carrier-mediated uptake of other amino acids cannot be detected, even in cultures maintained on amino acids as a nitrogen source or starved for nitrogen. This fact may contribute to the difficulty of isolating strains auxotrophic for amino acids other than arginine; conventiona...

Ammonium is an attractive nitrogen form for root uptake due to its permanent availability and the reduced state of the nitrogen. On the other hand, ammonium fluxes are difficult to control because ammonium represents an equilibrium between NH4+ and NH3, which are two N forms with different membrane permeabilities. There is increasing evidence that AMT-type ammonium transporters represent the ma...

Fertilisation has a significant impact not only on the yielding, but also quality of harvested biomass. Among energy crops, Miscanthus × giganteus are some most important plants used for combustion process. The chemical composition biomass effect nitrogen fertilisation (with dose 60 kg N ha?1) in different terms sampling content and uptake crude ash, potassium, calcium sulphur by rhizomes, stem...

BACKGROUND The amount of reactive nitrogen deposited on land has doubled globally and become at least five-times higher in Europe, Eastern United States, and South East Asia since 1860 mostly because of increases in fertilizer production and fossil fuel burning. Because vegetation growth in the Northern Hemisphere is typically nitrogen-limited, increased nitrogen deposition could have an attenu...

15N tracer techniques were used to measure rates of NH and NO uptake, dissolved organic nitrogen (DON) 1 2 4 3 release resulting from both ammonium (NH ) and nitrate (NO ) uptake, and NH regeneration at discrete depths 1 2 1 4 3 4 throughout the euphotic zone in Monterey Bay, California, at a site, H3, outside the plume of direct upwelling influence. In March 1993, 94% of the inorganic nitrogen...

Nitrogen uptake and metabolism are central for vegetative and reproductive plant growth. This is reflected by the fact that nitrogen can be remobilized and reused within a plant, and this process is crucial for yield in most annual crops. A population of 146 recombinant inbred barley lines (F(8) and F(9) plants, grown in 2000 and 2001), derived from a cross between two varieties differing marke...