A field experiment was conducted to examine the effects of different depths of NITROGEN (N) fertiliser placements on N ACCUMULATION, remobilisation and NO3--N content in soil of rainfed wheat. NITROGEN was applied on the surface (D1) and in the 10 cm (D2), 20 cm (D3) and 30 cm (D4) soil layers from 2010 to 2012. Compared with D1 and D2, D3 and D4 treatments obtained significant higher N distribution amounts in grain and N ACCUMULATION amounts at maturity. D3 and D4 treatments increased the N ACCUMULATION amount of vegetative organs at anthesis and at maturity. D3 treatment resulted in significantly higher N translocation amounts from vegetative organs to grains compared with D1 and D2 treatments and had no significant difference with D4 treatment. Compared with the D1 and D2, D3 and D4 treatments obtained significant higher NO3--N contents in the 20 cm to 120 cm soil layer at anthesis from 2011 to 2012. However, D3 treatment showed no significant differences with D1 and D2 treatments at maturity in terms of the NO3--N contents in the 40 cm to 100 cm soil layer. D4 treatment produced the highest NO3--N contents in the 40 cm to 140 cm soil layer. Grain yield, N uptake efficiency, apparent N recovery efficiency, N agronomic efficiency and N partial factor productivity were significantly increased by D3 and D4 treatments. These results suggest that the D3 treatment facilitates the best wheat production and highest efficiency among all treatments.

In the present study, some nutritional imbalances, specific ion toxicity and yield-ion concentration relationships in maize under water, NITROGEN (N) and salinity stresses were assessed. Effect of different levels of irrigation water (I1=1. 0ETc+0. 25ETc as leaching, I2 =0. 75I1 and I3 =0. 5I1) as main plot, salinity of irrigation water (S1=0. 6, S2= 2. 0 and S3=4. 0 dS m-1) as sub-plot and N fertilizer rates (N1=0, N2=150 and N3=300 kg N ha-1) as sub-sub-plot on maize (cv SC 704) were investigated in a splitsplit-plot design with three replications during 2009 and 2010. Results showed that salts accumulated in soil were 28. 4% higher in I2 compared with other irrigation treatments. Soil nitrate concentration was statistically higher under I3 and S1 treatments (83% and 10%, respectively) compared with other irrigation and salinity levels. There was no K+ deficiency caused by salinity; however, salinity resulted in statistically lower K+/Na+ compared with no saline conditions. Plants took up 25% higher N in I2 compared with other irrigation levels. Furthermore, N uptake by plants decreased by an average of 18% under salinity condition indicating that higher N application rate above the required level under saline water application put the environment at the risk of groundwater N contamination. Results of this study confirmed the fact that Na+ ACCUMULATION in soil was more detrimental than Cl-ACCUMULATION for maize irrigated with saline water. Besides, according to threshold values for soil ions, the optimum levels of irrigation and N fertilizer for maize might be lower under saline water application. Furthermore, based on the grain yield reduction coefficient, maize required a higher level of K+ and K+/Na+ under deficit saline water irrigation for avoiding yield losses

Quantitative information of NITROGEN ACCUMULATION and remobilization under varying environmental and growing conditions are limited for wheat (Triticum aestivum L.) cultivars in Golestan province of Iran. This information is used for quantifying NITROGEN partitioning between leaves and stems during vegetative stage and the remobilization to the grains during reproductive stage. This experiment was carried out at research farm of the Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran, in 2005-2006 using randomized complete block design with four replications. The experiment was conducted with four spring bread wheat cultivars t (Kohdasht, Shiroudi, Tajan and Zagross) in three planting dates (14 Dec., 20 Jan. and 20 Feb.).Results revealed that N concentration (%) in leaves was 5% up to beginning of grain growth stage, and then declined linearly to 2% at physiological maturity. Stem N% decreased from 2.3% at anthesis to 1.7% in senesced stems at maturity. Results indicated that a positive relationship exists between NITROGEN content of grain and whole plant, as each unit increase in the whole plant NITROGEN (%) increased grain NITROGEN content by 0.89%.This relationship can be used to estimate grain NITROGEN content. NITROGEN partitioning in vegetative stage was 58% to stems and 42% to leaves. Those cultivars that had greater remobilization efficiency from stem reserves in reproductive stage also had higher grain NITROGEN content. A significant relationship was observed between NITROGEN remobilization and NITROGEN content of vegetative organs at maturity stage that can be used to predict NITROGEN remobilization. It was found that NITROGEN remobilization decreased by 25.4% per each unit increase in NITROGEN content in vegetative organs. The parameter estimates and functions obtained in this study could be used to simulate N ACCUMULATION and remobilization for spring bread wheat cultivars.

Effect of different amounts of NITROGENous fertilizer as Urea (0, 50, 100, 150, 200 and 250 kg N/ha) was studied on growth, yield and nitrate ACCUMULATION in cucumber cv. Daminos. The experimental design was a complete randomized block with four replications. Several plant and fruit characteristics consisting of number of male and female flowers, lengh and weight of plants, number and weight of fruits, dry matter percentage of fruits and plant and eventually yield of first and second grade fruits were recorded. Nitrate amout in fruits as measured for every harvest of morning and afternoon. Results showed that the number of female flowers increased with increasing the level of NITROGEN. This increment was correlated positively with the increment of plant length. NITROGEN application at levels of 150-250 kg/h showed significantly higher total yield compared to that lower levels. Nitrate amount in fruit tissue was increased with increasing level of applied NITROGEN and reached its highest level with application of 250 kg/h NITROGEN. The level of nitrate was always higher in fruits harvested in the morning compared to those harvested in the afternoon. The level of nitrate reached its toxicity threshold in treatments of 200 and 250 kg/h NITROGEN when harvested in the moning but for afternoon harvest it reached toxicity threshold when 250 kg/h NITROGEN was applied. It can be concluded that NITROGEN can be applied at 200 kg/h if it is supposed to be harvested in the afternoon but only 150 kg/h NITROGEN can be recommended if it is supposed to harvest in the morning.

In order to study the effect of water and NITROGEN stress on biomass in Maize variety KSC704, an experiment was conducted at Agricultural and Natural Resources Research Center of Neyshabour city in year 2013. The experimental design was randomized complete block with three replications. The main treatments consisted of two levels of water stress 80 and 60 percent of water requirement in each of the three stages of growth vegetative, reproductive and grain filling and secondary treatments of two levels of 100 and 50 percent NITROGEN. Most of biomass was produced in the control (no stress) equal to 22.8 ton/ha. Water and NITROGEN stress applied at different stages of growth, has decreased final biomass. Water and NITROGEN stress at vegetative growth stage had highest effect on biomass and lowest biomass was measured in IR60N50 equal to 13.2 ton/ha. Statistical analysis of results also showed that effects of water and NITROGEN stress and interaction effects of irrigation and NITROGEN had significant effect on biomass and water use efficiency at 1 percent level. The highest water use efficiency were obtained in control (I100N100) treatment with 1.77 kilograms per cubic meter. According to the results, it is recommended to maximize water use efficiency, water and NITROGEN use completely done.

The influence of NITROGEN (N) rates on mineral nutrient uptake in stem and seeds, proline and carbohydrate in flag leaves of Wheat (Triticum aestivum L. Var Chamran) under saline conditions was studied in a field experiment in 2003 and 2004. The experiment was conducted using a split plot design with three replications. The treatments comprised five levels of salinity: 1.5, 5, 10, 15 and 20 ds/m in main plot and three NITROGEN levels: 50, 100 and 150 kg N/ha in sub plot. Salinity treatments were applied in a clay–loam soil by water with NaCl and CaCl2 (5:1 by wt). The results showed, the nutrient uptake was influenced by both salinity and N treatments. With the Exception of magnesium in seed, salinity increased NITROGEN, calcium and magnesium concentrations in seed and stem in both years. By increasing salinity levels, the concentration of potassium in stem and seed decreased and Sodium concentration increased. In the stem the concentration of Sodium in the 20 ds/m was about 17 and 22 times more in the first and second year, respectively. In these experiments, by increasing salinity and NITROGEN treatments, proline concentration in flag leaves increased in the two stages (flowering and milky stages) in both years. Salinity had similar effect on carbohydrate ACCUMULATION in both stages, but NITROGEN treatment had two different effects on carohydrate concentration. In flowering stage, by increasing NITROGEN application, carohydrate concentration increased but in milky stage decreased.