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In order to investigate the effect of nitrogen fertilizer and plant density on the agronomic characteristics of rice cv. Tarom Hashemi, a field experiment was carried out as a randomized complete blocks design with three replications during 2018 and 2019 in a farm located in Sari, north of Iran. The present study consisted of 10 levels of plant density (hills m-2 ) and N fertilizer, named T1 (20 hills + [50 percent after transplanting + 50 percent at the beginning of tillering]), T2 (20 hills + [33.3 percent after transplanting + 33.3 percent at the beginning of tillering + 33.3 percent at panicle formation]), T3 (20 hills + [40 percent after transplanting + 40 percent at the beginning of tillering + 20 percent at the end of panicle emergence]), T4 (20 hills + [33.3 percent after transplanting + 33.3 percent at panicle formation + 33.33 percent at the end of panicle emergence]) as a control, T5 (30 hills + [33.3 percent after transplanting + 33.3 percent at the beginning of tillering + 33.3 percent at panicle formation]), T6 (30 hills + [40 percent after transplanting + 40 percent at the beginning of tillering + 20 percent at the end of panicle emergence]), T7 (30 hills + [33.3 percent after transplanting + 33.3 percent at panicle formation + 33.3 percent at the end of panicle emergence]), T8 (30 hills + [25 percent after transplanting + 25 percent at the beginning of tillering + 25 percent at panicle formation + 25 percent at the end of panicle emergence]), T9 (40 hills + [33.3 percent after transplanting + 33.3 percent at panicle formation + 33.3 percent at the end of panicle emergence]), and T10 (40 hills + [40 percent after transplanting + 40 percent at panicle formation + 20 percent at the end of panicle emergence])..The results showed that the effect of year was not significant on grain yield. But the grain nitrogen concentration was lower in the second year (with a difference of 0.185 percent). The maximum total number of tillers per hill (18.61 tillers), panicle length (25.0 cm) and harvest index (40.9 percent) were obtained under T1, T2 and T3 treatments, respectively. Grain yield was not affected by the experimental treatment, however, its maximum (6865 kg ha-1 ) was obtained under T9 treatment due to an increase in the number of panicles per square meter (510 panicles), indicating an increase of 19.0 percent compared to the control treatment (T4). A density of 40 hills per square meter with nitrogen splitting of 33.3 percent after transplanting + 33.3 percent at panicle formation + 33.3 percent at the end of panicle emergence (T9) is recommended to achieve maximum grain yield of rice under the conditions of this experiment in northern Iran. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of chemical and biological nitrogen fertilizer on canola, a field experiment was conducted as a split plot based on a randomized complete block design with three replications at the research station of the Faculty of Agriculture, Yasouj University, located in Deshtrum region, in 2019 . The main factor consisted of nitrogen fertilizer (zero, 25, 50, 75, 100 and 125 kg/ha of pure nitrogen from urea source) and the secondary factor consisted of nitroxin biofertilizer contained Azotobacter and Azospirillium bacteria (use and non-use). The results showed that nitrogen fertilizer and nitroxin had a significant effect on all investigated traits. Nitrogen fertilizer significantly increased plant height, number of lateral branches, chlorophyll index and oil yield. The highest grain (8790.60 kg/ha) and biological (23910.93 kg/ha) yield were obtained in 125 kg/ha of nitrogen and the use of nitroxin. With the consumption of 125 kg/ha of nitrogen and nitroxin, the lowest percentage of seed oil, and contrastingly the highest percentage of seed protein (36.65%) was obtained. In general, combined application of biofertilizer with chemical nitrogen increased grain, biological and oil yield. Nitroxin bio -fertilizer could reduce the consumption of chemical nitrogen fertilizer. The results showed that there was no significant difference between the application of 50 kg/ha of nitrogen + bacteria and the application of higher levels of nitrogen (75, 100 and 125 kg/ha) alone in most of the investigated traits. [ABSTRACT FROM AUTHOR]

In order to define a suitable sowing date and effect of nitrogen fertilizer on quinoa, a randomized complete block design field experiment was conducted based on a split-plot design with three replications in 2019 at Ahar, Iran. Experimental treatments included: Five sowing dates (Feb. 24, Mar. 11, Mar. 25, Apr. 9 and Apr. 25) as main plot and five levels of nitrogen fertilizer (0, 90, 180, 270 and 360 kg ha-1 ) as sub plots. Results indicated that maximum 1000-seed weight (3.48 g) was obtained at sowing date of 25 Apr. under 180 kg ha-1 nitrogen and the highest grain yield and biomass were observed at sowing date of 25 Apr. with application of 270 and 360 kg ha-1 nitrogen fertilizer. The highest plant height and grain nitrogen percentage were obtained in the sowing date of 25 Apr. with application of 90, 180, 270 and 360 kg ha-1 . A significant increase in nitrogen agronomic efficiency was observed with increasing application of nitrogen from control to 90 kg ha-1 in all sowing dates. The highest growing period (with 137 days) was observed at sowing date of 24 Feb. and the lowest growing period (with 95 days) was observed at sowing date of 25 Apr. Generally, the sowing date of 25 Apr. with application of 270 kg ha-1 nitrogen fertilizer is suitable for Ahar region owing to the shortest growing period and highest grain yield and biomass. [ABSTRACT FROM AUTHOR]

Accumulation of nitrogen in vegetative organs and its translocation to grain of wheat are important processes that determine the yield and quality. In order to investigate the effect of supplemental irrigation nitrogen fertilizer on dry matter remobilization, yield and yield components of three wheat cultivars a split-split plot experiment was conducted based on randomized complete block design with 3 replications at Research Field of Kurdistan University, Sanandaj, west of Iran, during 2016-2017. Treatments were two levels of Irrigation (rainfed and irrigation at the booting stage) as main-plots, three rainfed cultivars (Sardari, Azar2, and Rejaw) as subplot and three rates of nitrogen (50 kg/ha N (N1), 100 kg/ha N (N2) and 100 kg/ha N plus 20 kg/ha N (N3) foliar application in Heading stage) as sub-subplot. The results showed that supplementary irrigation increased the concentration of leaf chlorophyll a, chlorophyll b, proline, and glycine betaine and decreased the electrolyte leakage. Supplemental irrigation also increased leaf nitrogen, chaff and total nitrogen content at flowering stage. Rejaw cultivar had the highest leaf nitrogen remobilization efficiency and the lowest total nitrogen remobilization efficiency. N1 fertilizer treatment led to the lowest concentration of leaf chlorophyll a and b, proline, glycine betaine, and nitrogen, and stem, chaff and total nitrogen in both flowering and maturity stages. Nitrogen remobilization was affected by supplementary irrigation and different rates of nitrogen fertilizer. It seems that supplementary irrigation in the booting stage leads to an increase in nitrogen content in the vegetative organs, which is transferred to the grain during the seed filling stage. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the influence of different nitrogen sources on qualitative and quantitative characters and economic benefit of potato (Sante cultvar). This experiment was conducted in a randomized complete block design with four treatments and three replicates at Behbahan Agriculture Research Station, Behbahan, south-east Iran, in two years (2014 and 2016). Treatments were: 0 nitrogen fertilizer, 50% nitrogen from chemical fertilizer (as urea) + 50% nitrogen from vermicompost (50% M+50%V), 75% nitrogen from chemical fertilizer + 25% nitrogen from vermicompost (75% M+25%V) and 100% nitrogen from chemical fertilizer (100% M). The total and marketable tuber yield, nitrogen use efficiency and agronomic nitrogen use efficiency in 75% M+25%V were significantly higher than the other treatments. Application of vermicompost in both treatments significantly increased stem and tuber number and decreased tuber nitrate content as compared with 100% M. The effect of vermicompost on tuber dry matter percentage was not significant. Economic evaluation indicated the highest benefit may be achieved from 75% M+25%V. Supply of 75% required nitrogen fertilizer through vermicompost and 25% nitrogen from mineral fertilizer (as urea) can increase yield and qualitative characters of potato and farmers’ incomes in Behbahan. [ABSTRACT FROM AUTHOR]