کارایی جذب نیتروژن

To investigate the effect of tillage systems and nitrogen fertilizer on corn characteristics, in 2016 and 2017, a research field was conducted in the research farm of Islamic Azad University Chalous Branch during two cropping years.The experiment was performed as a split-plot in a randomized complete block design with three replications. Experimental factors include tillage at three levels (no-tillage, conservation tillage and conventional tillage) in the main plot and nitrogen fertilizer sources at four levels, including non-application of zero, 33, 66,and 100% of the recommended amount of nitrogen fertilizer based on the test. The soil was on a subplot.Comparing the average effect of tillage showed that the highest grain yield was obtained in conservation tillage treatment at the rate of 10247 kg/ha-1. Comparison of tillage's average effect showed that the highest biological product was received in conservation tillage at the rate of 15754 kg/ha-1. Comparison of the average interaction of the year in tillage also showed that the highest NUPE was observed in the conservation tillage treatment in the second year at the rate of 0.90 kg.kg-1, which showed an increase of 47% compared to the treatment no tillage in the first year. NUPE in tillage treatments increased in the second year compared to the first year, which was higher in conservation and non-tillage tillage treatments. Comparison of the average treatment of nitrogen fertilizer showed that the highest grain nitrogen was obtained in the treatment of 100% nitrogen fertilizer at the rate of 1.98%, which showed an increase of 25.7% compared to the control treatment.In general, the results of this study showed that by applying conservation tillage methods, the least damage can be done to the soil structure, and through this, maximum yield and efficiency can be achieved in the corn plant. Therefore, according to grain yield, the most appropriate treatment for the study area is the use of conservation tillage in the case of fertilizer application of 66% nitrogen.

Nitrogen is one of the important nutrient elements necessary for the production of agricultural products, but the excessive application of nitrogenous chemical fertilizers and their leaching cause environmental pollution. Crops’ cultivars with high nitrogen use efficiency is one of the environmental friendly aproaches to mitigate this problem.

To evaluate grain yield and nitrogen use efficiency in barley genotypes under low input conditions (without fertilizer application), a field experiment was conducted in research field of the agricultural faculty of Shahed University, Tehran, Iran in 2016-2017 cropping season. Thirty six barley genotypes, purified for three cropping seasons, were planted using simple alpha lattice design with two replications.

The results showed that genotypes; 106, 107, and 68 had the highest grain yield (7963, 7920 and 7900 kg ha-1, respectively), the highest nitrogen use efficiency (58.6, 58.5 and 56.9 kg.kg-1, respectively) and the highest nitrogen uptake efficiency (2, 2 and 2.25 kg.kg-1, respectively). The results of multiple regression analysis showed that the three variables of nitrogen use efficiency, nitrogen uptake efficiency, and biomass yield explained 98.2% of variation in grain yield. Principle component analysis revealed that barely genotypes divided into four groups. The first group included genotypes; 88, 119, 54, 107, and 68 for nitrogen uptake efficiency and nitrogen use efficiency, grain yield and quality. These genotypes are suitable for low input cropping systems to increase nitrogen use efficiency.

The results of this experiment indicated that further investigations are required for recommendation of barley genotypes with higher nitrogen efficiency and grain yield for low input cropping systems.

Some studies have reported that application of chemical fertilizers, especially nitrogen, is one of the most appropriate methods to increase crop production and maintain food security in the world. However, it should also be noted that the improper use of nitrogen fertilizers can disrupt natural ecosystems. Alternative methods can be used to prevent this, such as the use of plants with biological nitrogen fixation (e.g., legumes). Faba bean is one of the most important varieties of this family (Fabaceae) and contains 24-30% protein and 51-68% carbohydrates. This plant is one of the most important spices of the genus (Vicia) and has a high yield compared to other legumes. Due to its environmental, economic and agroecological performance, faba bean can improve the sustainability of agricultural ecosystems. Corn (Zea mays L.) is one of the most important annual cereals. However, maize cultivation is not economical because it requires nitrogen fertilizer, and improper use of nitrogen also increases ecosystem instability. Incorporating legumes into cropping systems is critical for sustainable management of agricultural systems and reducing nitrogen fertilizer requirements for corn production.
 
A two-year experiment was conducted in 2018-2019 as a factorial experiment based on a randomized complete block design with three replications at the research farm of the Faculty of Agriculture and Natural Resources, university of Mohaghegh Ardabili, Ardabil, Iran. The experimental treatments were different plant densities of faba bean (25, 35, 40 and 80 plants m-2) and different nitrogen fertilizer rates (0, 100, 200 and 300 kg ha-1) of forage corn. In this experiment, the faba bean variety Shadan was planted and manually harvested at the physiological maturity stage. The corn variety was a single cross hybrid 201, which was planted at a density of 80000 plants ha-1 in the rows with faba bean residues. At the V5 stage of corn, N fertilizer (as urea) was applied in 3 stages. Three corn plants were harvested at the milk stage and then oven dried at 70°C for 72 h and weighed. Traits studied in this experiment included chlorophyll index, plant height, root nodule dry weight, root dry weight, number of root nodules, and grain yield in faba bean, and chlorophyll index, protein harvest index, plant height, number of leaves per plant, physiological nitrogen efficiency, nitrogen uptake efficiency, and dry matter yield in forage corn. Statistical analysis of data was performed using SAS 9.4 software, and significant differences between treatment means were tested using the Duncan's Multiple Range Test at P< 0.05.
 
Faba bean
The highest grain yield (g m-2), plant height (cm) and chlorophyll index of faba bean were obtained at the density of 80 plant m-2. At the densities of 25 and 35 plants m-2, the number of root nodules and the dry weight of root nodules (g) were the highest. As plant density increased, root dry weight (g m-2) also increased, so that the density of 80 plants m-2 had the highest root dry weight per m2. The highest fertility rate was observed at the densities of 80 and 40 plants m-2.
Corn
Our results showed that the interaction between faba bean density and N fertilizer had effects on plant height, chlorophyll index, protein harvest index, physiological nitrogen efficiency, nitrogen uptake efficiency, and dry forage yield. The results of the mean comparisons showed that the highest dry forage yield was obtained at the density of 40 faba bean plants+200 kg N ha-1 an increase of 155% over the control treatment. The highest number of leaves was observed in the treatments at the density of 40 faba bean plants+100 kg N ha-1, at the density of 40 faba bean plants+200 kg N ha-1 and at the density of 35 faba bean plants+200 kg N ha-1. The density of 40 plant of faba bean+100 kg N ha-1 and the density of 40 plant of faba bean+200 kg N ha-1 had the highest plant height. The highest chlorophyll index was obtained at the the density of 40 faba bean plants+200 kg N ha-1. Finally, the results showed that employment of faba bean in rotation and non-application of nitrogen fertilizer increased nitrogen uptake efficiency of forage corn.
 
Comparison of the different treatments showed that the density of 40 plants of faba bean and 200 kg N ha-1 was superior in most of the evaluated traits. Overall, the results suggest that the use of faba bean in crop rotation is an appropriate approach to reduce the use of chemical fertilizers in agricultural systems, according to the results, the use of the density of 40 plants of faba bean and 200 kg N ha-1 were recommended under the same weather conditions.

Lentil (Lens culinaris Medic.) is an important grain legume adapted to cool climates. It is cultivated on 155700 hectares in Iran with 94.7 % of this area under rainfed conditions. The average lentil yield in Iran is 1195 and 476 kg per hectare in irrigated and rainfed farms, respectively. Low productivity is due to use of local varieties, which have low yield potential, and poor agronomic management practices applied by the farmers such as limitation or inappropriate distribution of fertilizer. Nitrogen is an essential element for the growth of crops and its deficiency exists almost everywhere. It is the limiting factor in the crop growth more than any other element, unless use the nitrogen as a fertilizer. Despite the numerous advantages of nitrogen fertilizers, excessive consumption of nitrogen can cause pollution of surface and ground water through leaching and erosion and also increases costs. According to an adequate supply of nutrient elements by careful use of fertilizers, especially in poor soils, yield increases and nitrogen use efficiency improves. The objective of this study was evaluation of yield of two lentil cultivars under the influence of nitrogen fertilizer and also, investigation the nitrogen uptake, utilization and use efficiency to determine the best level of nitrogen fertilizer and cultivar for the study area.

The experiment was conducted as split plot based on randomized complete blocks design with three replications at the Agricultural Research Station, Ferdowsi University of Mashhad, during growth season 2015-16. Nitrogen fertilizer (in three levels i.e. 0, 40 and 80 kg per hectare) and cultivar (Birjand and Robat) were in main plots and sub plots, respectively. Nitrogen fertilizer was applied as urea to the plots before sowing. The sowing date was 9th March in 2016. Sampling was done at harvest time and included pod number per plant, seed number per pod, 100 seed weight, seed yield, biological yield and harvest index. Percentage of biomass nitrogen were measured with the Kjeldahl method and the efficiency index calculated by using the following equation:NupE= Noff/ Ns
NutE b= B/ Noff
NutE s= Sw/ Noff
NUE b= B/ Ns
NUEs= Sw/ Ns                                                                                                                            
Where NupE is the nitrogen (N) uptake efficiency, Noff is the N in above ground dry matter, Ns is the soil N supply, NutEb is the N utilization efficiency based on biomass basis, B is the total above ground biomass at harvest, NutEs is the N utilization efficiency based on seed yield, Sw is the seed weight, NUEb is the N use efficiency based on biological yield, NUEs is the N use efficiency based on seed yield. Data were analyzed with the SAS software; obtained averages compared with LSD test at the 5% level.

The results showed that the interaction effect between nitrogen fertilizer and cultivar was significant on yield components, seed and biological yield. 40 kg nitrogen fertilizer per hectare and Birjand cultivar showed that maximum of pod number per plant (33.47), seed (338. 23 kg per hectare) and biological yield (3291.68 kg per hectare). Maximum of seed number per pod and 100 seed weight were obtained in treatment of non-use of nitrogen fertilizer and Birjand cultivar and treatment of 40 kg nitrogen fertilizer per hectare and Robat cultivar, respectively. Interaction effect between nitrogen fertilizer and cultivar was significant on nitrogen content of biomass, nitrogen uptake, utilization and use efficiency based on seed and biological yields. 40 kg nitrogen fertilizer per hectare and Birjand cultivar showed that maximum of nitrogen content of biomass and nitrogen uptake efficiency. The highest nitrogen use efficiency based on seed yield (3.39 kg seed per kg Ns) and biological yield (33.48 kg biomass per kg Ns) were obtained in treatment of non-use of nitrogen fertilizer and Birjand cultivar that the difference was no significant with the treatment of 40 kg nitrogen fertilizer per hectare and Birjand cultivar. Analysis of correlation showed that, yield and nitrogen use efficiency had positive and significant correlations with the pod number per plant and nitrogen uptake efficiency, respectively. Also, there was positive and significant correlation between nitrogen uptake efficiency and yield.

The results of this study indicated that treatment of 40 kg nitrogen fertilizer per hectare and Birjand cultivar are able to achieve maximum yield and nitrogen use efficiency. However, Birjand cultivar is a late cultivar and requires the optimum planting date for cultivation in this region. According to the observed correlations, breeding of this plant should be cultivars that they absorb nitrogen with more efficiently, so that in addition to improving nitrogen use efficiency and reducing environmental pollution also yield increase.

To evaluate nitrogen use efficiency in intercropping replacement ratios of maize and bean, an experiment was conducted during two successive cropping years of 2014-2015 and 2015-2016 at Agricultural Research Station, Ferdowsi University of Mashhad, Mashhad, Iran. Experimental factors were arranged as split plots in randomized complete block design with three replications. The main plots consisted of sole culture of maize and bean, row intercropping with ratios of 50%:50%, 67%:33% (2 rows of maize: 1 row of bean) and 33%: 67% (1 row of maize: 2 rows of bean). Application and no-application of nitrogen (N) fertilizer (55 kg.ha-1) were assigned to sub plots. The results showed that different ratios of maize and bean intercroppings and application of nitrogen fertilizer had significant effects on grain yield and biomass as well as nitrogen use efficiency indices (such as uptake, utilization and productivity). Maximum grain yield and biomass of bean (3462.1 and 10124.5 kg.ha-1 respectively) and maize (5974.1 and 18321 kg.ha-1, respectively) were obtained from sole cropping of bean and maize. In both crops, N utilization efficiency was higher in all treatments when nitrogen productivity was calculated using grain yield. In nitrogen application treatment, the row intercropping ratio of 50:50 of bean and maize had higher nitrogen uptake efficiency for both crops. Also, the ratio of planting 1 maize: 1 bean (50% maize: 50% bean) had the highest total land equivalent ratio (1.10) using grain yield, nitrogen uptake efficiency (2.30) and nitrogen productivity efficiency (using grain yield (1.98) and biological yield (2.02)). Therefore, it can be concluded that the use of maize and bean row intercropping is an environmental friendly cfrop management pratctice to reduce nitrogen losses and improve its uptake efficiency, and to prevent the excessive use of chemical fertilizers and improve the productivity of these inputs in agroecosystems.

IntroductionSoybean is a member of leguminoseae family with average protein percentage of 40%, which needs a large amount of nitrogen fertilizer to get maximum yield. Using biofertilizers, beside chemical nitrogen fertilizers, can reduce proportion of chemical nitrogen demand without any undesirable effect on quantity and quality of its yield. Biological nitrogen fixation of soybean by Rhizobium japonicam can improve nitrogen use efficiency parameters beside its yield. This experiment was conducted with the aim of study the effect of different levels of nitrogen, bio-fertilizers and Nano-nitrogen on nitrogen use efficiency (NUE) and yield of soybean (Glycine max (L.) Merr.) cv. Williamz.
Material and MethodsA field experiment was conducted as a spilt plot in a randomized complete block design with three replications in 2013 at research center for agriculture and natural resources of Darab, Fars, Iran. Main factor was mineral nitrogen at three levels (zero, 75 and 150 kg N ha-1 ) and sub plot was nitrogen source at four levels (Rhizobium japonicum, nano-nitrogen, nitroxin and control). Rhizobium japonicum bacteria was inoculated in rate of 125 gr per 50 Kg seeds, nitroxin in rate of 0.5 L per 9 Kg seeds, and nano-nitrogen in rate of 10 L ha-1. The experimental plot dimensions were 2 x 4 m consisting of 4 rows of cultivated soybean 50 cm apart. The seeds were planted 5cm apart on each row. A furrow irrigation system was employed during experimental period. After the physiological maturity the experimental plots were harvested and yield, yield components, protein, protein yield, seed nitrogen content at ripening stage, nitrogen use efficiency (NUE), nitrogen utilization efficiency (NUTE), nitrogen uptake efficiency (NUE) and nitrogen harvest index (NHI) were measured.
Results and DiscussionThe results showed that the interaction of nitrogen and nitrogen source was significant for grain yield, harvest index, nitrogen percentage in the grain ripening phase, seed protein and protein yield. Mean comparison showed that the highest grain yield (2018 kg ha-1) obtained from application of 75 kg N ha-1 with Rhizobium application and the lowest grain yield (1476 kg ha-1) obtained from the no nitrogen fertilizer application. The highest seed protein percentage and seed protein yield observed in application of 150 kg N ha-1 with Rhizobium application. The highest nitrogen in the grain (1.51 %) was related to application of 75 kg ha-1 N with nano-nitrogen application. The highest nitrogen content of shoot in harvesting stage was achieved by integrated application of 75 kg ha-1 nitrogen and nano-fertilizer nitrogen. The highest nitrogen harvest index (NHI) (77.81 %) obtained from application 150 kg ha-1 N with nano-nitrogen application, maximum nitrogen use efficiency (NUE) (26.90 kg kg-1) was obtained from application of 75 kg N ha-1 and Rhizobium application and the minimum (12.66 kg kg-1) was obtained from application of 150 kg N ha-1 and Rhizobium. Generally, soybean production in Darab region had the best results with the use of 75 kg N ha-1 along with the Rhizobium japonicum application.
ConclusionsApplying of biofertilizers beside chemical nitrogen, could decrease chemical nitrogen use without any impact on qualitative and quantitative yield of soybean. According to the results of this study application of half of the recommended amount of nitrogen (75 kg N ha-1) and inoculation with Rhizobium japonicum bacteria (125 gr per 50 kg seeds) had the highest grain yield, harvest index, nitrogen use efficiency (NUE) and nitrogen harvest index (NHI). It seems that combined application of bacteria and chemical fertilizers can improve soybean performance and also reduce its chemical nitrogen demand. Our results suggested that, integrated application of 75 kg ha-1 nitrogen and Rhizobium can be suitable treatment to soybean production in Darab climatee.

Barely (Hordeum Vulgare L.) is one of the major grain crops from cereal family, which is the world`s fourth most important crop in terms of cultivation area and yield production after wheat, corn and rice. Iran`s share of world barely production is 2.7 million hectares, representing almost 1.86 % of total global barley production, according to Ministry of Agriculture Jihad statistics (2013). Nitrogen is one of the most important nutritional elements with a high consumption rate, which plays a pivotal role in the vital processes of plants. Lack of nitrogen is associated with the more significant limitation in producing crops compared to the other natural elements. Over-consumption of nitrogen fertilizer harms the environment, while it also has an intense restrictive effect on microorganism diversity and yield of the crops’ roots. Furthermore, less consumption of nitrogen than the required amount might be associated with the diminished yield of the crops (Beatty et al., 2010). To increase the efficiency of nitrogen consumption, we need nitrogen management strategies, traditional methods of plant breeding and biotechnology. The aim of this study was to evaluate the effects of different levels of nitrogen fertilizer on nitrogen use efficiency and yield of old and new barely cultivars in the two regions of Mashhad and Damghan.
The study was conducted at the research farms of Ferdowsi University of Mashhad and university of Agricultural Sciences of Damghan, Iran in the crop year of 2014-2015, using a factorial design based on completely random blocks with three replicas. Experimental treatments were combination of barley cultivars (five new cultivars: Fajr 30, Nosrat, Behrokh, Yousef and Nik, and five old cultivars: Reyhan, Eram, Afzal, Nimrooz and Karoon) and different levels of nitrogen fertilizer based on soil test from depth of 0-30 cm (the consumption of normal fertilizer, 50% less and 50% more than the recommended amount of nitrogen for barely). In this experiment, in addition to yield attributes, traits such as nitrogen use efficiency, nitrogen uptake efficiency, nitrogen productivity, nitrogen harvest index and seed nitrogen content were measured.
Result and The results of combined analysis of variance indicated that the effect of nitrogen fertilizer and cultivar was significant on the all studied traits. While the interaction of the location and cultivar was significant for nitrogen use efficiency, nitrogen productivity and yield, the other interactions were not found to be significant. The lower application of nitrogen than normal was compared with its excessive consumption, which indicated a reduction in the nitrogen utilization efficiency, uptake efficiency, productivity, harvest index, and nitrogen seed content in all the studied barely cultivars. The new barely cultivars exhibited higher nitrogen use efficiency than the old cultivars. Furthermore, maximum and minimum nitrogen use efficiency were respectively recorded for Behrokh cultivar at Mashhad region and Afzal cultivar at Damghan region, where nitrogen use efficiency of new cultivar of Behrokh was 57 % more than that of Afzal old cultivar. Accordingly, level of nitrogen use efficiency under the climate of Mashhad was approximately 33% higher than Damghan. The highest nitrogen uptake efficiency and harvest index were observed in Behrokh and Eram cultivars, respectively. In addition, maximum and minimum content of nitrogen in the seeds were registered for the cultivars of Nik and Afzal, respectively, so that the seed nitrogen content of Nik new cultivar was 22% higher than Afzal old cultivar. Comparison of average grain yield across the regions showed that the old cultivars consistently produced lower grain yield as compared to new ones where Yousef new cultivar gave the highest grain yield (6573 kg ha-1) in Mashhad and old Afzal cultivar had the lowest grain yield (3152 kg ha-1) in Damghan. Superiority of new cultivars compared to old cultivars could be attributed to their genetic enhancement in terms of yield production (Gabriella et al., 2003). It is also notable that all the studied features in the current research had significant positive associations with seed yield performance. Given the variable response of the cultivars in Mashhad and Damghan, different cultivars should be tested to identify those cultivars that are adapted to the climatic conditions of each region.

This study was carried out under temperate climate condition of Ilam province, Iran, during 2012-2013 growing season to determine the suitable crop rotation for enhancing nitrogen uptake, utilization, and use efficiency of wheat. A two factor experiment was laid out as split plot arrangement (RCBD) with four replications. The main plots consisted of 6 pre-sowing plant treatments (control, Perko, Buko, Clover, Oilseed radish and combination of three plants Ramtil, Phaselia, Clover), and sub-plots were allocated to four levels of nitrogen fertilizer (Zero, conventionally recommended fertilizer, 50% lower and 50% higher than the recommended fertilizer). Results showed that nitrogen use efficiency (NUE), nitrogen uptake efficiency (NUpE), nitrogen utilization efficiency (NUtE) and nitrogen efficiency ratio (NER) in wheat were significantly affected by crop rotation and nitrogen fertilizer and their interaction. The lowest and highest nitrogen use efficiencies were achieved in oilseed radish-wheat and fallow-wheat rotations. The greatest nitrogen use efficiency in oilseed radish-wheat was due to high utilization efficiency of nitrogen in the rotation. The greatest and smallest nitrogen utilization efficiencies (NUtE) were observed in oilseed radish-wheat and fallow-wheat rotations, respectively. Perko-wheat rotation with application of nitrogen at the conventional level for wheat brings about an acceptable economic yield and high nitrogen uptake and use efficiency and seems to be advantageous to other rotations.

Mother corm size and nutrient management are the most important factors in relation to nitrogen uptake of saffron (Crocus sativus L.). In order to investigate the effects of mother corms size and type of fertilizer on uptake and use efficiency of nitrogen in Saffron، a field experiment was conducted as factorial layout based on a randomized complete block design with three replications at Faculty of Agriculture، Ferdowsi University of Mashhad، Iran، during the years 2013 and 2014. The mother corm size (4 g and lower (small)، 4. 1–8 g (medium)، 8. 1-12 g (relatively large) and over 12 g (large)) and fertilizer sources (cow manure 25 t ha-1، chemical fertilizer (N+P) and control) were the first and second experimental factors، respectively. In both years، the larger mother corms (8. 1-12 g and more) significantly resulted in greater nitrogen content (g m-2) of replacement corms and whole plant of saffron. In addition، uptake and use efficiency of nitrogen were significantly increased with increasing mother corms size. In the first and the second years، nitrogen use efficiency in manure treatment was significantly higher than that of chemical fertilizer (by 21 and 61%، respectively).

The competition for nitrogen is an effective factor can be affected crop- weed interactions. In order to determine of black seed nitrogen use efficiency and harvest index at different weed competition durations, a field experiment was conducted at Agricultural Research Station, Ferdowsi University of Mashhad, Iran, during 2009- 2010. The experiment was Randomized Complete Block Design (RCBD) with 12 treatments and 3 replications. Two sets of treatments consist of weed-infested and weed-free periods were used. At the first set of treatments, weeds compete with black seed up to 0, 14, 28, 42, 56 and 70 day after emergence (weed-infested periods). At weed free treatments, plots were kept free of weeds up to the mentioned stages. Results indicated that different weed interference durations had significant effects on nitrogen contents of seed, stubble and biomass of black seed. Nitrogen harvest index was significantly affected by different weed competition durations. In this experiment, uptake (recovery), physiological (internal) and use (agronomic) efficiency of nitrogen in black seed decreased with decreasing weedfree and increasing weed-infested periods. However, these competition periods had more effect on nitrogen uptake efficiency than physiological efficiency of nitrogen.

In order to study of nitrogen absorb and use efficiency of wheat (Triticum aestivum) and wild oat (Avena fatua) 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. The first factor was competition between wild oat (densities of 0, 2, 4, 6 and 8 plants per pot) and wheat (density of 8 plants per pot) and the second factor was five different levels of nitrogen (1, 4, 8, 12 and 16 mM). The experiment was finished at the end of vegetative growth stage of wheat and data were analyzed using regression analysis. Results showed that nitrogen percentage (NP), nitrogen absorb efficiency (NAE) and nitrogen use efficiency (NUE) in wheat and wild oat were affected by experimental factors. Nitrogen content increased in wheat as well as wild oat when nitrogen level increased to reach to asymptote at 8 mM nitrogen. NP was decreased in wheat (except at 1mM nitrogen) when weed density increased, but was not affected in wild oat by wheat competition. NAE of wheat was decreased exponentially in all weed densities and was not affected by wild oat competition. NAE of wild oat followed a positive significant linear relationship with adding of density. It indicated the growth up of nitrogen absorb of wild oat in competition situation. NUE was similarly affected in wheat as well as wild oat.