The peculiarity of nitrogen nutrition for legume-cereal mixtures is that due to the intravital transfer of mineral nutrition elements from the legume component of the mixture to the cereal component and vice versa, the cereal component receives nitrogen from the air symbiotically fixed by the legume component. This explains its better development in the mixture than in single-species sowing without the use of nitrogen fertilizers. In unfavorable conditions for legume-rhizobial symbiosis, when the assimilation of air nitrogen is weakened, and the legume and cereal components of the mixture are deficient in nitrogen, therefore, the issue of nitrogen fertilizer use expediency for legume-cereal mixtures is relevant. We have studied the effects of low and medium doses of nitrogen fertilizers including 30, 60 and 90 kg ha-1 (as treatments N30, N60 and N90) on the content and yield of crude protein with the grain yield of the vetch-wheat mixture under the conditions of sod-podzolic sandy loam soil in the central region of the Non-Chernozem zone with insufficient and optimal moisture. The protein content (% of dry matter) was determined by the calculation method according to the nitrogen content (N% × 6.25). On the control without nitrogen fertilizers, the protein content in vetch seeds and in wheat grain under the conditions of optimal moisture (2019) was higher than under the conditions of insufficient moisture (2018), by 0.4% and 0.3%, respectively. Nitrogen fertilizers increased the protein content in wheat grain by 0.2 - 0.4% during both years of study. The protein content in vetch seeds under the influence of nitrogen fertilizers increased only under the conditions of insufficient moisture by 0.2-0.7%. The protein yield with the wheat grain yield during both years of study upraised, as the dose of nitrogen fertilizers elevated by 1.6 - 2.7 times, and by the vetch harvest and insufficient moisture it remained unchanged, and by optimal moisture it droped by 13.7-34.7%. The protein yield with the grain yield of the mixture elevated by 44.4-91.1% under the influence of nitrogen fertilizers in arid conditions completely due to the wheat protein increase, while in conditions of sufficient moisture it droped by 5.2-17.8% due to the vetch protein decrease. Nitrogen fertilizers increased the competitiveness of wheat mixed with vetch under the conditions of insufficient moisture by 1.7-3.0 times, and under the conditions of optimal moisture by 1.9-4.1 times.

In order to examine the effect of the quantity of Nitrogen fertilizer and bush density on vegetative and productive function of henna medicinal plant (Lawsonia inermis)  factorial experimentation in the form of block plan was carried in three stages in agriculture research center in south of kerman  province in corp of 2012. The first factor containing Nitrogen fertilizer in 4 levels including 50,100,150,200 kg net Nitrogen fertilizer and the second one as bush density in three level including 110000-160000-210000, bushes were examined. The measured traits included weight of fresh stem, stem, height weight of dried stem and leave, and total dried and fresh weight and all of productive traits including weight of fresh and dried flower, number fruits in bush, number of seeds in a fruit, number of seeds in frui weight of 1000 seeds and function of  seeds. The results indicate that that effect of bush density, nitrogen fertilizer qualities and contrast effect between two factor on weight of fresh and dried leave Statistically was in to concern up to 1%, but nitrogen fertilizer shows no difference in statistical respect on this quality, nitrogen fertilizer effect on all of productive qualities except number of seeds in fruit Was up to 5% fruitless as the main consumption of henna is its leaves. Finally with density of the bush 160000 to 210000 bushes in 1 hectare and consuming 50kg nitrogen fertilizer with function of dried leaves weight up to 3.54, 3.34 tons in one hectare is recommended. Even though consumption of 100kg nitrogen fertilizer in hektar resulting of maximum effect on dried weight.

An experiment was performed in Ardabil (2012) to investigate the effects of manure consumption in different amounts on reducing nitrogen fertilizer consumption in potato cv. Agria. This research was conducted in factorial design based on randomized completely blocks design in three replication  in which two manure factors in three levels (control, 30 and 60 tons/h) and nitrogen fertilizer in 4 levels (25%, 50%, 75% and 100% recommended) were investigated. Results showed that increased manure usage led to increased tuber yield, and the most yields were obtained from 60 tons/h manure usage. Manure causes increased tuber’s average weight per plant, number of tubers per plant, tubers average weight, plant’s wet and dry weight, plant height and tuber’s nitrate. Also, nitrogen fertilizer caused increased potato tuber yield in which the most yields were obtained from nitrogen fertilizer up to 100% recommended, and it also caused other properties increase. Significantly, increased nitrogen usage increased tubers nitrate and tubers nitrate obtained from nitrogen fertilizer up to 100% recommended. Results from variance analysis showed that manure-nitrogen fertilizer interaction in growth properties was not significant but, in 1% probability level it was statistically significant in tuber and nitrate yield components properties. Increased manure usage from recommended 30 to 60 tons/h and nitrogen from 50 to75 percent have had better effects on total properties, especially in terms of nitrate accumulation. So, the highest yields were obtained from manure usage up to 60 tons/h.

To meet the needs of the global population (9.7 billion people) until 2050, a 45 percent increase in corn production is required. Efforts to enhance corn production may be informed, among others, precise N management. This research aims to determine nitrogen dynamics and precise nitrogen nutrient management in corn cultivation using a leaf chlorophyll meter and nitrogen response tests to predict corn yield in tropical upland acid soils. This research was conducted in an Ultisol and verified in an Oxisol. The trial was arranged in a randomized completely block design with eight treatments: 0, 45, 90, 135, 180, 225, 270, and 315 kilograms nitrogen per hectare, repeated three times. The chlorophyll content of corn leaves was measured at 45 and 60 days after planting, using a chlorophyll meter. Data analysis was carried out on vegetative growth and yield, as well as nitrogen content in the soil, leaf, and grains. The study found that the application of nitrogen fertilizer at the rate of 180 kilograms per hectare can alter nitrate concentrations in soil and significantly increases nitrogen uptake, growth, and corn yield. The maximum nitrogen fertilizer rate was 274.5 kilograms nitrogen per hectare, with corresponding chlorophyll meter readings of 52.8 and a corn yield of 8.58 tons per hectare. The corn yield at the rate of maximum nitrogen fertiliser (8.58 tons per hectare) was not significantly different from that at the rate of 180 kilogrammes nitrogen per hectare (8.54 tons per hectare). There was a strong correlation between corn yields and chlorophyll meter values with correlation coefficient of 0.92. The study revealed that applying nitrogen fertilizer at the medium rate of 180 kilograms per hectare can lead to an increase in nitrogen uptake, growth, and corn yield on tropical upland acid soils. There was not a significant difference in corn yield between the rate of nitrogen fertilization at 180 kilograms per hectare and the maximum rate of 274.5 kilograms nitrogen per hectare. In terms of sustainable agriculture management, the medium rate of 180 kilograms nitrogen is recommended for maximizing crop yield on the upland acid soils and minimizing potential environmental impacts associated with excessive use of fertilizers. There is a strong correlation between leaf chlorophyll meter readings and corn yield, suggesting the chlorophyll meter can serve as a reliable tool in the study site in determining optimal fertilizer rates.

In order to evaluate the impact of different amounts of nitrogen fertilizer on growth and yield of two forage sorghum cultivars, a 2-year field experiment was carried out at the College of Agriculture, Shiraz University, Shiraz, Iran during 2010 and 2011 growing seasons. Two factorial experiments were carried out in randomized block design with three replicates, in which the treatments included nitrogen fertilizer at three levels: 69 (N1), 138 (N2) and 205 (N3) kg N ha-1 and two sorghum cultivars: Pegah and KFS2. The results showed that nitrogen fertilizer enhanced plant height, leaf area index, fresh weight, total dry weight and biological yield significantly so that these traits were higher in N3 as 5.71, 22.8, 8.13, 22.5, and 8.7% than N1, respectively. Furthermore, increasing nitrogen rate had additive effect on crop growth rate, relative growth rate, biomass duration and leaf area duration. Comparing the cultivars, it was found that, plant height, fresh weight, total dry weight and biological yield were higher in Pegah than KFS2 cultivar. Results also showed that most of the studied traits were superior for Pegah under N3 treatment; so, Pegah cultivar and application of 205 kg N ha-1 might be offered for similar agro-climatic conditions.

Since alkaloids are nitrogenous compounds, the availability of nitrogen (N) is expected to play an important role in the biosynthesis and accumulation of alkaloids in plants. Nitrogen has been found to increase the content of alkaloids in some of the medicinal plants.
The aim of this study was to compare the effects of nitrogen bio-fertilizers, conventional nitrogen fertilizer, and nitrogen nano-chelate fertilizer on the content of tropane alkaloids in Hyoscyamus niger L.
This experiment was conducted in a randomized complete block design (RCBD) with 8 treatments, and 3 replications. The experimental treatments included 2 L.h-1 nitroxin, 1 kg.h-1 Azotobacter, and 10 t.h-1 vermicompost each as bio-fertilizer, 150 kg.h-1 urea as a conventional chemical fertilizer of nitrogen, and nitrogen nano-chelate fertilizer with three amounts of 3, 5, and 7 percent, and control treatment (without nitrogen fertilizer).
The results showed that the effects of bio-fertilizers, conventional nitrogen fertilizer, and nitrogen nano-chelate fertilizer were significant on the scopolamine and hyoscyamine content in black henbane at the level of 1%. The highest content of hyoscyamine (HYO) was related to the treatments of 5% per hectare nitrogen nano-chelate, and the maximum amount of scopolamine (SCO) was observed in the treatments of 3 and 5% nitrogen nano-chelate fertilizers. On the other hand, the lowest values of hyoscyamine and scopolamine were related to the treatment of 7% nitrogen nano-chelate fertilizer, and nitroxin treatment, respectively.
Generally, the highest yield of alkaloids content in black henbane were obtained by application of 3 and 5% nitrogen nano-chelate fertilizers.

To survey the effects of flooding during the reproductive growth stages of aerenchyma formation and ethylene production in soybean cultivar DPX experiment  the completely randomized factorial was in 2012 in Gorgan University of Agricultural Sciences and Natural Resources. Factors examined include nutrition levels in three levels (1 - inoculated with bacteria JaponicumBradyRhizobium 2 - non-inoculated plus nitrogen fertilizer (urea) 3 - non-inoculated without nitrogen fertilizer) and the second factor is the duration ofwaterlogging stress (0, 5, 10 and 15 days). Based on the results obtained with increasing duration of flooding stress on the plant, ethylene production increases. The slope was slowly at first and then increases exponentially. Among the nutritional treatment of ethylene production , non-inoculated plus nitrogen treatments was higher than the other two treatments, and the non-inoculated treatments without fertilizer lowest ethylene production was observed. Images of cross sections of soybean plants showed that the stress increases with the duration of flooding stress signsaerenchyma tissue formation was observed in soybean plants. 15 days of flooding treatment aerenchyma tissue formation was observed at all levels of nutrition.

In order to evaluate the impact of crop residues (zero, 25 and 50%) and nitrogen (zero, 125 and 250 kg ha) on weed seed bank and potato yield, two-years research was conducted as a split plot arranged in randomized complete block design in Rozveh Agriculture Research Station, Freidan-Esfahan. Numbers of weed species in seed bank, aboveground, and both seed bank and aboveground were 1, 2 and 8 respectively. Amaranthus retroflexus L. was dominant weed in seed bank in the both years. Weed seed bank was significantly lower in both N rates than control in the both years with no significant difference between the rates. Weeds biomass with increased use of nitrogen fertilizer increased. In 25 and 50 percent of crop residue treatments, weed seed density was greater than control. 125 kg N ha -1 with 25 percent of crop residue treatment produced the highest tuber yield (27850 kg ha-1), although weed biomass was also high in this treatment. The results showed that management of nitrogen fertilizer application and weed control by applying crop residue crops in rotation will change.

This research, conducted in Gotvand, southwest of Iran, compared the energy consumption of two cucumber production systems: field and greenhouse production systems. In this study, energy inputs of two production systems of cucumber (including seed, pesticide, human labor, machinery, diesel fuel, electricity, organic manure, chemical fertilizer) were determined from questionnaires completed by farmers. The results of the experiment indicated that the energy input of the two cultivation systems was not significantly different in input energies. In both cucumber production systems, the most input energy was allocated to nitrogen fertilizer (57% and 53% for field and greenhouse, respectively) followed by diesel fuel (21% in both production systems). Non-renewable energies accounted for 90 and 88% of the total energy input to the farm and greenhouse systems, respectively. Total output energy of field and greenhouse cucumber production system was 33000 and 34000 MJ, respectively. Reducing the consumption of nitrogen fertilizer through the use of appropriate crop rotation is a suitable solution to improve energy efficiency in the cucumber production system.

In order to investigate the effect of water treatment and nitrogen fertilizer application on remobilization and grain yield of bread wheat cultivars, an experiment was carried out as split-split plot design based on randomized complete blocks with three replications. Three levels of irrigation (full irrigation, withholding irrigation at heading, withholding irrigation at anthesis) were assigned to main plots, different times of nitrogen fertilizer application (application of 120 kg/ha nitrogen in four different times: 20 kg at sowing + 100 kg/ha at tillering, 20 kg at sowing + 100 kg/ha at bolting, 20 kg at sowing + 50 kg at tillering + 50 kg at bolting, 20 kg at sowing + 50 kg at tillering + 50 kg at heading) were randomized in sub-plots and five bread wheat cultivars (Zarrin, Pishgam, Urum, Zare, Mihan) were assigned to sub-sub-plots. Withholding irrigation at different developmental stages of wheat increased remobilization percentage of all cultivars. However, application of nitrogen at the heading stage reduced remobilization. The highest and lowest remobilization were recorded for Urum and Zarrin with 62.13% and 20.33%, respectively. Grain yield was significantly reduced with the reduction of water availability. Mean grain yield of all cultivars was 7.500 ton/ha under full irrigation, which reduced to 6.500 ton/ha when irrigation was withheld. Nitrogen fertilizer applicationimproved the grain yield of wheat cultivars. The highest grain yield was obtained for Mihan by 9.39 ton/ha under full irrigation and nitrogen application at sowing + tillering + heading. The higher grain yield of tolerant cultivars under water deficit treatments was attributed to remobilization of unstructured carbohydrates from shoot to grain. It seems that selection of cultivars with higher translocation of dry matter and contribution of pre-anthesis assimilates in grain filling under water stress, can be a suitable strategy to produce high yielding cultivars under water deficit stress condition.