In order to study the effect of salinity stress and nitrogen forms on nitrogen remobilization from root to shoot following defoliation and shoot dry matter production, a research in the form of factorial experiment based on randomized block, was designed in three replications. Treatments include: 1) nitrogen forms containing a) biological N fixation (N1), b) 6mM NH4NO3 (N2), c) biological N fixation+, 6mM NH4NO3 (N3), 2) salinity in two levels containing 1/1 ds/m (S0) and 12 ds/m (S1) and 3) two Iranian alfalfa cultivars (Bami and Gharehyonjeh). Salinity stress decreased nitrogen availability in root and shoot, nitrogen remobilization and shoot dry matter. Percentage of this reduction in Ghareyonjeh cultivar was higher than Bami cultivar. According to positive correlation between nitrogen remobilization to shoot following defoliation and shoot dry matter production (r=0.86), it was hypothesized that the effect of salinity on reduction of alfalfa shoot regrowth resulted from reduction in nitrogen remobilization. The highest nitrogen remobilization was related to N2 and N3 treatments although the percent of remobilization in N1 treatment was higher. Due to salinity, amount of nitrogen remobilization decreased in all nitrogen forms but percentage of this reduction was higher in N2 and N3 treatments. Percentage of increase in sodium content due to salinity in N2 and N3 treatments was higher than N1. According to appositive correlation between root sodium content and nitrogen remobilization (r=-0.83), it is possible that greater decrease in nitrogen remobilization and shoot dry matter production following defoliation in N2 and N3 treatments resulted from greater increase in sodium content in these treatments.

Preanthesis stored dry matter in wheat (Triticum aestivum L.) is important under a Mediterranean climate because grain filling greatly depends on remobilization of preanthesis assimilates. The experiment was carried out at Marvdasht region during 2010-2011 using Complete Randomized Block, Split-split Plot Design with three replications. Main plots consisted of Irrigation treatments which, were I1 (Nonstressed) and I2 (Post anthesis water stressed plots with 50% FC). Sub plots consisted of fertilizer treatments, which were nitrogen at rates of 50 (Low N) and 200 (High N) kg ha-1. Subsub plots, wheat and barley cultivars, were Shiraz, Marvdasht, and Nosrat and Rihaneh. Results showed that application of 200 kg N ha-1 had positive effect on all traits and produced more grain yield. Between wheat and barley Marvdasht cultivar produced the highest grain yield. Drought stress increase dry matter remobilization and its efficiency. Dry matter remobilization and its efficiency were higher in wheat cultivars than barley cultivars. Increasig nitrogen application increased dry matter remobilization and decreased its efficiency. Interaction effects of nitrogen and irrigation was significant in most traits. In general, it seems that in order to obtain high grain yield nitrogen should be adjusted with amount of irrigation water.

IntroductionSafflower is an oilseed plant tolerant to water deficit, and have an important role in oil production. Drought stress is the most important factor limiting crop yields in many parts of the world, including Iran. Nitrogen plays a key role in plant growth and this role is highly related to the amount of water and how it is distributed. Bacteria of the genus Azotobacter are one of the most important growth-promoting bacteria in plants due to their abundance and extent of spread, which is able to improve the availability of nitrogen. In areas where most rainfall occurs in winter and early spring, crops will face water constraints at the end of the growing season. In such conditions, finding cultivars and lines that have good performance in non-stress and drought stress conditions and have a suitable response to Azotobacter and nitrogen fertilizer is of special importance.The aim of this experiment was to evaluate the response of safflower genotypes to the application of Azotobacter and nitrogen fertilizer under different moisture conditions.Materials and methodsThis experiment was carried out during two growing seasons (2015/2016 and 2016/2017), in Sarableh Agricultural Research Station, Ilam Province. The factorial scheme 4 × 6 experiment was performed in both years in a randomized complete block design with three replications under terminal drought stress and non-stress conditions. The distance between these two environments was considered to be 10 meters so that the humidity of the two adjacent environments did not affect each other. Experimental factors included seed inoculation with A. chroococcum using urea chemical fertilizer at four levels [without using any N fertilizer source (control), seed inoculation with A. chroococcumalso without use N fertilizer, seed inoculation with A. chroococcum + 50% N of urea fertilizer source, and 100% N of urea fertilizer source], and six safflower genotypes (312-S6-697, PI-401478, PI-253895, PI-306974, Padideh, and Sina).After harvesting and determining grain yield in both experimental conditions, stress tolerance indices including stress sensitivity index (SSI), mean productivity (MP), tolerance (TOL), geometric mean yield (GMP), stress tolerance index (STI) and Modified stress tolerance indices (MSTI) were calculated. Statistical calculations of analysis of variance and mean comparisons were performed using SAS 9.1 software. STATGRAPH software was used to principal component analysis and drawing biplot diagrams.Results and discussionThe results showed that among the nitrogen source treatments, the highest percentage of grain yield reduction with 48% in drought stress conditions compared to non-stress conditions was related to the application of 100% nitrogen chemical fertilizer. This result shows that in drought stress conditions, the application of 100% nitrogen fertilizer due to the increase of biological substances, causes an imbalance between the roots and plant aerial parts in water absorption and water loss through transpiration by aerial organs, which in Extremely serious damage to the economic sector of the plant.Azotobacter inoculation + 50% nitrogen fertilizer application had the highest mean productivity index and the lowest stress sensitivity index among nitrogen source treatments, although it was not significantly different from other nitrogen source treatments. These results indicate that the use of Azotobacter in combination with the application of 50% nitrogen fertilizer reduces the damage caused by drought stress in safflower. Sina cultivar was the most tolerant genotype under drought stress under Azotobacter inoculation and 100% nitrogen fertilizer application. In conditions of inoculation with Azotobacter + 50% of nitrogen fertilizer application, Sina and Padideh cultivars are located in the area of high production potential and low drought sensitivity in the vicinity of vectors related to drought tolerance indicesConclusionSina cultivar in inoculation treatment with Azotobacter and consumption of 100% nitrogen fertilizer, Padideh cultivar in addition to Sina cultivar in combined application of Azotobacter + 50% nitrogen fertilizer had the highest tolerance to terminal drought stress; Therefore, in selecting drought tolerant genotypes, special attention should be paid to nitrogen source factor.

The effect of salinity on nitrogen absorption and leaf chlorophyll content of wheat (cv. Falat) was studied in two separate greenhouse traits, both in a completely randomized block design with three replication. Three levels of nitrogen (0, 1.19 and 5.94 g Urea/pot) and three levels of salinity (0, 150 and 300 mol/m3 salts) were used as treatments. Salinity conducted by combining sodium and calcium chloride in a 1:10 molar ratio and pots were irrigated with modified Hogland solution in close system. Leaf chlorophyll and nitrogen contents, stomatal resistance, specific leaf weight (SLW) specific leafnitrogen (SLN) were measured at booting and anthesis stages. The results showed a high correlation between SPAD reading (leaf chlorophyll) and leaf nitrogen content and SLN. Leaf nitrogen content reduced but SLN and stomatal resistance increased by increasing salinity levels. SPAD reading increased up to salinity levels of 150 mol/m3 but reduced at higher salt concentration. Adjusted SPAD reading on SLW (SPAD/SLW) showed higher correlation with salinity levels compared to unadjusted SPAD reading and may used as indicator for severity of salt stress.

Because of uneven distribution of rain over the year and variable water supply either due to shortage of water or failure of the irrigation system, terminal drought is a major problem for wheat growth and yield stability in most regions of Iran. On the other hand, nitrogen deficiency is a major constraint to wheat production in this region. To evaluate the interaction between nitrogen and water supply, this experiment was conducted in year 2003/2004 at Ramin Agricultural Research and Education Center, Ahwaz, Iran. The experiment was a split- split plot in a completely randomized block design. Wheat was grown under three irrigation levels (50%, 75% and 100% full irrigation) and two wheat cultivars (Yawaroos and Chamran) and four nitrogen fertilization applications (0, 80, 120 and 180 kg ha-1). Results showed that grain yield increased with increasing N application. Grain yield at 0, 80, 120 and 180 kg N ha-1 was 341.04, 565.19, 625.66 and 651.52 g m-2 respectively. The difference between grain yield of 50% full irrigation treatment with 75% and 100% full irrigation was significant. Grain yield at 50%, 75% and 100% full irrigation was 523.11, 553.58 and 560.80 g m-2 respectively. Yawaroos grain yield (558.45 g m-2) was significantly higher than Chamran grain yield (533.21 g m-2).The interaction between nitrogen and water supply on grain yield was significant. At zero N level, increasing water supply did not increase grain yield, but at 80, 120 and 180 kg N ha-1 levels, grain yield was improved by increasing water supply. Also, by increasing N levels at any water supply levels, grain yield increased. In all treatments except variety treatment, grain yield increased and was controlled by biomass production and increasing the redistribution of carbon reserves. The difference between grain yield of varieties was due to the difference between their HI. It could be concluded that although reduced irrigation to 50% full irrigation may reduce the potential maximum yield of farmers receiving full irrigation, probably benefits a larger number of farmers and results in greater overall wheat production. In addition, increased nitrogen prior to terminal drought when there is not water limited may yield satisfactory results seen in all water supply treatments that has been imposed during terminal growth period.

Introduction: Legume crops as human and animal feed are high in protein and have a positive effect on the yield of other crops when grown in rotation with cereals or as cover crops. However, drought can reduce pulse grain yield by 10 to 100 percent. It has been observed that drought stress has different effects on the yield of various genotypes of lentils,additionally, drought stress reduces grain yield in various cultivars of pinto beans and other genotypes of beans. According to reports, nitrogen can effectively mitigate the damaging effects of drought stress on maize. It has also been reported that the application of fertilizer treatments to various chickpea cultivars increases yield. The creation of stress-resistant plant cultivars has always been regarded as an effective method for mitigating the negative effects of stress. Consequently, the purpose of this study was to examine the impact of irrigation stress and varying nitrogen fertilizer levels on yield and yield components of bean genotypes. Materials and Methods: In 2020, two separate experiments (normal irrigation and low irrigation) were conducted on the research field of the school of Agriculture and Natural Resources at the University of Tehran in order to evaluate the effect of low irrigation stress and different levels of nitrogen fertilizer on bean plant yield and yield components. The experiment was designed with a factorial layout based on a completely randomized block with three replications. The experimental treatments included two levels of irrigation (normal irrigation and 50% normal), five levels of bean genotype (Pak, Dorsa, Goli, Sadri, D81083), and three levels of nitrogen fertilizer (no nitrogen fertilizer, 50% nitrogen fertilizer, and 100% nitrogen fertilizer). SAS 9. 4 and Excel 2016 were utilized for data analysis, combined analysis of variance of both experiments, comparison of means, and graphing. Also, Minitab was utilized to examine the homogeneity of error variance. Results and Discussion: Prior to the combined analysis of variance, the homogeneity of variance of the experiments was examined, and it was determined that the homogeneity of variance of error in none of the experiments (at the one percent level) was rejected. The results of a combined analysis of variance indicated that irrigation stress and bean genotypes had a significant effect on all investigated traits. In addition, the application of different nitrogen fertilizer levels had a significant effect on all traits except harvest index and number of grains per pod. The dual interaction of treatments and the triple interaction of irrigation, nitrogen, and genotype on the number of seeds per pod. A comparison of the means of different levels of irrigation revealed that the values of all yield traits and yield components of beans decreased when low irrigation stress was applied. Significant reduction in grain yield, biological yield, and harvest index percentage under drought stress conditions were 30. 5, 23 and 12 percent, respectively, when compared to the fully irrigated treatment, demonstrating the significance of drought stress effects on bean crop yield. Conclusion: The findings of this study indicate that drought stress and nitrogen fertilizer have a significant effect on yield and yield components for all bean genotypes. In such a way that a 30% reduction in grain yield is observed with low irrigation stress. Nevertheless, application of nitrogen fertilizer caused relative resistance of bean genotypes to low irrigation stress, so that using 100% nitrogen fertilizer treatment, the highest grain yield was obtained for white beans (4481 kg / ha), pinto beans Sadri (4373 kg / ha), and red bean (3936 kg / ha), among the five genotypes. In general, the findings of this study indicated that the destructive effects of low irrigation stress or drought on bean grain yield could be mitigated to some extent by selecting suitable bean genotypes and applying appropriate nitrogen fertilizer levels.

Optimum management of intra- and interspecific competitions are key subject in most agroecosystems. The objective of this experiment was the study effect of intra- and interspecific competitions and N rates on yield and yield components of wheat which was carried out in Agricultural Faculty of Shahid Chamran University of Ahvaz during 2011-2012. The experimental design was split-plot based on RBCD with 3 replications. The main plots including 4 N rates (i.e. 0, 50, 100 and 150 kg N ha-1) and sub-plots including 4 different competition pattern: (i.e. without competition, intraspecific competition, interspecific competition and intra- and interspecific competition). Our results showed that both nitrogen and competition pattern had significant effect on quantity and quality of wheat yield. The highest grain yield was obtained in no competition and application of 100 or 150 kg N ha-1 (i.e. N100D1W0 and N150D1W0). Grain yield reduced by increasing in competition intensity. The lowest grain yield was obtained in N0 treatments. In addition, the highest protein percent was obtained in ¬ the highest nitrogen application rate, but it is reduced by increase in competition intensity. Moreover, in lower N levels, interspecific competition had the highest negative effect on wheat crop yield. But, at the highest N level, intraspecific competition had the same effect on wheat crop yield.

The nitrogen (N) nutrition, crop yield, and responses of wheat to arbuscular mycorrhizal fungi (AMF) were tested in an experimental field under free-air ozone concentration [O3] enrichment (FACE) conditions. The experiment included three treatments: ambient [O3] (Ambient), elevated [O3] (FACE, targeted at ambient [O3]×1.5), and elevated [O3] inoculated with an AMF consortium consisting of several Glomus species (FACE+AMF). AMF inoculation responsiveness of wheat was estimated by comparing plants grown in unsterilized soil inoculated with the exogenous AMF and in untreated soil containing indigenous AMF. Compared with the Ambient, relatively higher N contents but lower shoot biomasses of wheat plants were observed in the FACE treatment without AMF inoculation from the tillering stage in February and heading stage in April, respectively, which significantly (P<0.05) decreased grain yield by 28% at harvest in June. Under the FACE condition, compared with the non-inoculated treatment, AMF inoculation significantly (P<0.05) increased root colonization rates both at the tillering stage and heading stage, and also significantly (P<0.05) increased shoot biomass at the heading stage and, hence, significantly (P<0.05) increased grain yield by 40% at harvest. However, AMF inoculation significantly (P<0.05) decreased total N content in wheat shoots at the tillering stage, suggesting that AMF consortia may enhance plant tolerance to elevated [O3] by elevating root colonization rate rather than plant total N content at early growing stages.

Background and objectives: Chenopodium quinoa is a facultative halophyte plant which has been considered for cultivation in saline soils. Although most studies of the nutritional requirement of quinoa focus on nitrogen consumption management. Since the plant is considered for organic production in Peru and Bolivia and is also grown after crops such as potatoes, fertilizer is not recommended and the plant uses the fertilizer residues of the previous crop (19). Under these conditions, the optimal use of fertilizers, especially nitrogen fertilizers, to prevent lodging, mechanized harvesting and increase yield is very important. Climate conditions have a major impact on quinoa performance. The most important stress on the central plateau, in addition to salinity, is heat stress during the pollination and grain filling period, which causes a sharp decrease in yield (21). The purpose of this experiment is to optimize nitrogen fertilizer management in changing environmental conditions. Materials and methods: In order to determine quinoa fertilizer requirements under normal and heat stress during pollination period the experimental was conducted based on complete randomized block design in three replications, it was performed in Sadough Research Station of Yazd. Treatment consisted of nine treatments with different amounts of nitrogen (50, 100, 150 and 200 kg of urea ha-1) and splitting (two splitting at planting and early floral initiation and three splitting at planting, early floral initiation and flowering) plus a control treatment with three replications. Quinoa cultivation of Titicaca was carried out on September 1, 2017 and August 7, 2018. Applied irrigation water salinity after sowing was 8 dS/m and after emergence 14 dS/m saline water applied every two weeks. After harvesting, yield and yield components and nitrogen percentage of grain were measured. The efficiency of nitrogen consumption, partial efficiency, recycling of nitrogen consumption and the growing degree day for each growth stage were calculated. Data analysis was performed for each year separately due to the significance of the Bartlett test with SAS v9. 1 software. Results: The results showed that the level of application of fertilizer treatment had a significant effect on yield and biomass production. In the first year, the maximum grain yield obtained at 200 kg ha-1 with seed yield of 2 t ha-1. At lower level of fertilizer application, the adsorption efficiency and the amount of nitrogen recycled were higher, and the treatments of the three splitting were better than the two. At higher levels of fertilizer, the effect of splitting was less than lower levels of fertilizer. The amount of harvested available nitrogen in the control treatment was 2. 8 and at 200 kg ha-1 was 6. 3 g m-2. The highest recycling efficiency was observed in 50 kg treatment with 3 splitting. The percentage of seed nitrogen in the control was significantly lower than the fertilizer treatments and there was no significant difference between the fertilizer treatments, which shows the plant's ability to remobilize nitrogen to seeds and maintain protein percentage in low-input systems under saline condition. In the second year with heat stress during the anthesis period, grain yield and nitrogen yield decreased by 62% and 59%, respectively. The effect of thermal stress during the quinoa pollination period reduced the efficiency of fertilizer use and severely reduced yield, but did not affect the percentage of grain nitrogen and the thousand kernel weight. Conclusion: The fertilizer requirement, the efficiency of fertilizer application and the recovery of quinoa seed nitrogen changed under different climatic conditions, although the percentage of nitrogen accumulated in the grain did not change significantly, so to achieve the desired result, fertilizer management would be altered in different climatic and soil conditions.

The effect of drought stress on nitrogen and SPAD reading of wheat (cv Falat) was studied in a complete randomized block design with 3 replications; in the green house. Five levels of drought stress (-0.3, -1, -3, -5 and -7 b) were used as treatments. Soil water curves were plotted using presser plate at a wide range of soil water potential. Water requirement for each treatment determined with weighing by day of each treatment. SPAD reading, nitrogen content, stomatal resistance and specific leaf weight (SLW) of flag leaf and two leaves under flag leaf were measured at anthesis stage. Results showed that with increasing drought stress SPAD reading, nitrogen content, stomatal resistance and SLW increased and there was a high relationship between drought stress and SPAD reading. It was concluded that SPAD reading is a good index of nonstomatal resistance for preduction water stress severity.