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In order to investigate the effects of water deficit stress effects, different rates of nitrogen and plant density on remobilization, current photosynthesis and grain yield in oily sunflower var. Iroflor, an experiment was carried out in field Agriculture and Research center of West-Azerbaijan during 2011 and 2012 cropping seasons. The experimental was conducted as split-split-plot base on Randomized Complete Block Design (RCB) with 3 replications. The main factor was consisted irrigation treatment including optimum irrigation, moderate stress and sever stress which irrigation was done after depletion of 50%, 70% and 90% of available water, respectively. Three nitrogen levels of 100, 160 and 220 kg N haG1 were considered as sub plots and sub-sub plots consisted of three plant populations of 5.55, 6.66 and 8.33 plants m2. The results of combined analyzes showed that severe drought stress reduced the grain yield by 60% compared to the optimum irrigation condition. Comparison of two-year-mean revealed that severe drought stress in compared with optimum irrigation dry matter remobilization rate decreased about 30 percent. Also, severe drought stress led to 35% reduction of current photosynthesis efficiency in compared with optimum irrigation. In each level of nitrogen fertilizer, increasing plant population led to increase contribution of remobilization but current photosynthesis contribution decreased. Therefore, due to reduction of current photosynthesis rate in severe drought stress condition, contribution of current photosynthesis decreased so that increasing of (contribution of, deleted) remobilization contribution prevented reduction of seed yield.

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To evaluate the effects of nitrogen and water stress on allelopathic potential of sorghum (Sorghum bicolor) on the seed germination traits of safflower (Carthamus tinctorius), a factorial experiment was carried out in randomized complete design (CRD) with three replications in the greenhouse and laboratory, College of Agriculture, Shiraz University, Shiraz, Iran in 2012-13. Treatments included irrigation [Normal (I1) and water stress (I2)] and nitrogen [control (no nitrogen), Urea (200 kg N ha-1), Nitroxin (Azotobacter) and Nitrokara (Azospirillum and Azotobacter) inoculation per kg seeds]. Extracts were prepared from sorghum shoot resiude in 5, 10, 15 and 20 (W/V) and were applied to individual Petri dishes distilled water was used as control treatment. Also, foliar applications of extracts were applied in treatments under the greenhouse conditions and sorghum dried residues were also mixed with the soil in amounts of 0, 5, 10, 15, and 20 g after the first irrigation. Analysis of variance showed that interaction effects of sorghum extract type and its concentration had significant effects on all traits except relative water content. Safflower germination percentage reduced with increase in concentration. 5, 10 and 15% concentrations of Nitrokara under normal irrigation had 34, 22 and 12%, effects on allelopathy index of safflower respectively. Whereas concentration of 20% extract, decreased allelopathy index by 71%. The effects antagonist on length and dry weights of roots and shoots was observed when biofertilizer treatments (Nitroxin and Nitrokara) applied. In addition, more synergist effects were obtained when urea extract was appliedt under water stress. The results of foliar application revealed a decrease in CAT and POD activities in leaves of safflower when urea was usedunder water stress conditions. However, the lowest germination rate and primary growth of safflower was abserved when urea applied under water stress conditions.