vali feiziasl
Abstract
Introduction: Nitrogen is the main component of fertilizer programs necessary for production of high quantity dryland barley. This element is the second limiting factor, after water in dryland areas. So for economic production of barley, the proper nitrogen fertilizer application is essential to increase ...
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Introduction: Nitrogen is the main component of fertilizer programs necessary for production of high quantity dryland barley. This element is the second limiting factor, after water in dryland areas. So for economic production of barley, the proper nitrogen fertilizer application is essential to increase seed quantity and quality in Iran dryland areas. Many researchers have been confirmed that dryland barley yield increased by nitrogen application management. Nitrogen fertilization in dryland areas can increase the use of soil moisture, and improve barley yields to some extent. Different studies have been confirmed interactions between water stress and nitrogen fertilizers on barley, especially under field conditions. From the nitrogen management factors, timing and amount of nitrogen application is known as the most important aspect. This project established in order to study nitrogen rates and nitrogen application time's effects on nitrogen requirement, nitrogen agronomy use efficiency (NUE) and crop characteristics of various dryland barley genotypes in cold and semi cold drylands of Iran.
Materials and Methods: This study was carried out in split-split plot in a RCBD in Dryland Agricultural Research Institute (DARI), Maragheh; where nitrogen application times (fall, 1/2 in fall and 1/2 in spring and 2/3 in fall and 1/3 in spring) were assigned to the main plots, nitrogen rates to sub plot (0, 30, 60, 90 and 120 kg/ha), and 5 dryland barley genotypes to sub-sub plots (Sahand, Abidar, Dayton/Ranny, Alpha/ Gumhuriyet/ Sonja and B-C-74-2)in 4 replications during 2007-2010 years. The Rainfall were 177-498 mm.yr-1 (long term mean is 365 mm.yr-1) in cropping years in DARI station. Soil samples were collected from 0-25 cm for determining total N, P-Olsen, K-Ammonium acetate, TNV, OC, Soil texture, pH, EC and Fe, Mn, Zn and Cu-DTPA before sowing and collected from 0-2, 20-40 and 40-60 cm depths in sub-sub plots in shooting stage (GS32) for determining NO3− andNH4+. Ammonium measurement in the soil KCl extracts were down by spectrophotometry method and colorimetric reaction at 655 nm. Also, Absorption spectrophotometry method was used for determination of nitrate in soil extract based on its UV absorbance at 210 nm. In this method two measurements were carried out; one before (by Zn coated by Cu) and second after reduction of nitrate). Using the difference between these two measurements, concentration of nitrate in the extracts was determined.
Results and Discussion: The results showed that nitrogen application rates significantly increased (p
mohammad banayan
Abstract
Detection of rainfall characteristics in arid and semi-arid regions such as northeast of Iran has a critical role in any adaptation and mitigation plan to drought. The main goal of this study was to determine the rainy season starting date and daily rainfall threshold by using Rainfall Uncertainty Evaluation ...
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Detection of rainfall characteristics in arid and semi-arid regions such as northeast of Iran has a critical role in any adaptation and mitigation plan to drought. The main goal of this study was to determine the rainy season starting date and daily rainfall threshold by using Rainfall Uncertainty Evaluation Model. The Starting Analysis Date (SAD) characterize the beginning of a new rainy season in a given region, whereas, the Rainy Season Beginning Date and the Rainy Season Ending Date are used to determine the Rainy Season Length. In this study, seventeen locations in northeast of Iran with available long daily rainfall data (24 to 48 years) were selected. Our results indicated three annual courses of rainy season, 12 locations showed a uni-model annual course with shorter values in summer (A courses), 4 locations indicated uni-model with shorter rainy season length across April and March (B courses) and only 1 location showed bi-model annual course (C courses). These classifications were confirmed by multivariate statistical methods analysis. SAD was determined by differences between shortest median RSL and the shortest median RSL of the first day of each month. According to this approach SAD values for different classes determined as: July 1st in (A) region, March 1st in (B) region and February 1st in (C) region. Appropriate daily rainfall threshold was 1.0 mm for only 3 locations, and the highest value of this index obtained in Torbat-j location (2.2 mm), therefore 1.0 mm value which traditionally is in use as daily rainfall threshold need to be revised.
