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Aims: Saffron is one of the plants, whose allelopathic effect of various organs have been reported to affect seed germination of some weed species. The present research was conducted with the aim of evaluating the allelopathic effect of extraction solution of leaves and corms of saffron (Crocus sativus) in phenological stages on seed germination of jimson weed (Datura stramonium).
Materials and Methods: In this experimental study, an experiment was conducted to study the allelopathic effects of saffron on jimson weed seed germination at research farm, Tarbiat Modares University Faculty of Agriculture in autumn 2014. The experiment was arranged as factorial split plot in a completely randomized design with 3 replications. The treatments included factorial combination of 2 extract types (water and alcohol), 3 tissue compositions of saffron organs, different concentrations of aqueous, and alcoholic extracts as the main plots and 3 different phonological stages of saffron were considered as sub-plots. One-way analysis of variance was performed through generalized linear model (GLM), using SAS 9.1 software, and drawing charts was done, using Excel2013 software.
Findings: The concentration and phonological stage of saffron had a significant effect on the germination percentage of Datura stramonium, but the main effect of organ type on this trait was not significant. The aqueous extract of saffron did not have significant effect on the germination of Datura stramonium germination at the phonological stage of the daughter corms at a concentration of 2g/l in comparison with other phonological stages, but at a concentration of 4g, it significantly decreased the seed germination.
Conclusion: Extract of saffron has an allelopathic potential, and germination traits, including germination percentage and plumule and radicle length of Datura stramonium in different phonological stages of saffron are affected by the aqueous and alcoholic extracts of different organs.

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The current study assessed the effects of common herbicides produced by different companies on broadleaved and grass weed control and quantitative traits of irrigated wheat. A two-year experiment (2013-2014 and 2014-2015) was designed as an RCBD with three replications. Experimental treatments included two control treatments (weedy and weed-free) and 15 herbicides produced by three Iranian companies (Ghazal, Golsam-Gorgan, and Gyah) and three international companies (BASF, Nufarm, and Syngenta). The results showed that H13 (bromoxynil + MCPA from BASF tank-mixed with clodinafop propargyl from Golsam Gorgan) and H14 (bromoxynil + MCPA from BASF tank mixed with clodinafop propargyl from Ghazal) treatments in 2014 and H5 (tribenuron methyl from Gyah) and H9 (clodinafop propargyl tank-mixed with tribenuron methyl from Golsam Gorgan) in 2015 almost completely controlled broadleaved and grass weeds. In 2014, H4 (2,4-D + MCPA from Nufarm) and H13 treatments with the averages of 7505 and 7338 kg ha^-1 ranked first and second in grain yield, while H9 and H12 (bromoxynil + MCPA from BASF tank-mixed with clodinafop propargyl from Gyah) with the averages of 7966 and 7917 kg ha^-1 were known as superior treatments in 2015. Averaged by years, the grain yield was 3185 kg ha^-1 at weedy treatment (H17). Although there were no significant differences between herbicides, the grain yield (averaged by years and herbicides) was boosted by 88% compared with the weedy treatment. It was concluded that more rainfall and desirable air temperature positively affected the efficacy of the herbicides.
 

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Effects of various fertilizers such as farmyard manure (FM), urea, and plant growth promoting rhizobacteria (PGPR, including the genera Azotobacter and Azospirillium) were checked on yield, fatty acids, protein, and oil contents of sunflower. A two-year field experiment was conducted in a semi-arid region in Iran in 2007 and 2008. The experiment was a split plot in a randomized complete block design with three replicates, with five fertilizer treatments as the main plots and two PGPR treatments as sub plots. Results demonstrated that the integrated fertilizers significantly increased the leaf area index, plant height, grain production, biomass, oil yield, and protein content in comparison with organic or chemical fertilizers. The maximum and minimum oil contents were obtained by applying 100% farmyard manure (F1) and 50% FM + 50% chemical (F3), respectively; however, opposite results were observed for protein content. When higher FM rates were used with PGPR, the saturated fatty acids (palmetic and stearic acids) declined significantly, while unsaturated ones (linoleic and oleic acids) were increased. The highest contents of linoleic acid (52.6%) and oleic acid (39.8%) were observed in F₃ and F₁ treatments, respectively. Bacterial inoculation also increased the leaf area index, plant height, biomass, grain and oil yields, oil and protein contents up to 12, 3.7, 7.8, 10, 6.5, 5.6 and 5%, respectively.

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Drought stress is one of the environmental factors influencing crops growth, development, and production. Two field experiments were performed in Karaj, Iran, to evaluate the drought tolerance indices of 17 winter rapeseed genotypes in 2015-2016 and 2016-2017 growing seasons. The factorial arrangement of treatments was set up as RCBD with three replications. To identify drought tolerant genotypes, several indices were used based on grain yield under normal and deficit irrigation conditions. Yield results showed that cultivars Artist (504.325 g m^-2) and L72 (391.525 g m^-2) were the superior treatments under normal and deficit irrigation conditions, respectively. According to correlation results, 3-D graphs were drawn based on Geometric Mean Productivity (GMP) and grain yield under normal irrigation and deficit irrigation to categorize the winter rapeseed genotypes in both years. In the first year, Zorica and Lauren were in group A, while in the second year; Mercure, SW102, L72, and HL3721 were in group A. Therefore, they had superior performance and stable grain yield under both irrigation conditions. Biplot diagram showed Lauren (first year) and Mercure (second year) were superior regardless of stress conditions. Altogether, under normal irrigation, Artist genotype, and under stress condition, Mercure, L72 and HL3721 genotypes could be used for cultivation.
 

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The effects of abiotic stresses on medicinal plants metabolism are well known, but how plants respond to the interaction of these stressors is little understood. Therefore, the current experiment was aimed to investigate changes in growth and concentration of various primary and secondary metabolites of A. vera grown under water deficit and different light intensity conditions. A split-plot in time research was laid out in a randomized complete block design with four replications in a research greenhouse. The factorial combination of four irrigation regimes (irrigation after depleting 20%, 40%, 60%, and 80% of soil water content) and three light intensities (50%, 75%, and 100% of sunlight) were considered as the main factors. Sampling time was considered as sub factor. The results showed that the highest leaf, gel, and peel fresh weights were observed when the plants were subjected to low light intensity and irrigation was done after depleting 20% soil water moisture. Plants developed under full sunlight produced more pups (4.30, 3, and 3.75 per plant, 90, 180, and 270 days, respectively) and leaves (14.25, 18, and 21.25 per plant, 90, 180 and 270 days, respectively) and showed the higher fresh (165.75 g per plant) and dry root (37.60 g per plant) weight. These traits decreased with increasing water deficit severity during all the sampling times. Glucose (79.30 mg g DW^{− 1}, 270 days), fructose (233.50 mg g DW^{− 1}, 270 days), aloin (27.68%, 90 days), proline (2.07 mg [g FW]^-1, 90 days) and phosphoenolpyruvate carboxylase (PEP-Case) (0.463 mmol NADH/g prot*min, 90 days) increased with increasing light intensity and water deficit severity during all the sampling times. Although high light intensity and water deficit led to yield and growth reduction, concentration of various primary and secondary metabolites increased. The results suggest that reduction in light intensity mitigates adverse effects of water deficit by inducing primary and secondary metabolites changes. It can be considered as an acclimation mechanism under water deficit conditions to avoid yield loss in A. vera production.

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Drought is a major abiotic stress in arid and semi-arid areas. This study examines how drought stress and different rootstocks affect aerial part physiology and macronutrient uptake in two seedlings of pear cultivars, 'Dargazi' and 'Louise Bonne,' grafted onto 'Dargazi' and 'Pyrodwarf' rootstocks. Treatments were well-watered as control (100% Field Capacity, FC), moderate (60% FC), and severe drought (30% FC). Drought stress decreased the Root-to-Shoot weight ratio (R/SH), Leaf Relative Water Content (LRWC), Soluble Protein (SP), Photosynthetic Nitrogen Use Efficiency (PNUE), leaf osmotic potential (Ψs), Leaf potassium (LK⁺), Root Calcium (RCa²⁺), Root Nitrogen (RN), Stomatal aperture (SA), net photosynthetic rate (An), transpiration rate (E), stomatal conductance (gs), and instantaneous carboxylation Efficiency of Rubisco (EiC) in all scion-rootstock combinations. Under drought stress, levels of proline (Prol), Glycine Betaine (GB), Total Soluble Carbohydrate (TSC), root potassium (RK⁺), leaf calcium (LCa²⁺), leaf nitrogen (LN), leaf and root phosphorus (P) increased. 'Dargazi' as the cultivar or rootstock showed better instantaneous Water Use Efficiency (WUEi), Nitrogen Utilization Efficiency (NUtE), and Nitrogen Uptake Efficiency (NUpE), with higher LN, LNO³⁻, LNH⁴⁺, Prol, and Ψs under severe stress. 'Louise Bonne' had higher amounts of R/SH weight ratio, Total Nitrogen Accumulation (TNA), leaf and root nitrate reductase activity (NRA),  An, intracellular carbon dioxide concentration (Ci), E, and root nitrate (RNO³⁻) under moderate stress. 'Pyrodwarf' rootstock demonstrated the highest TNA and RCa²⁺ under moderate stress conditions. These results indicated that 'Dargazi' demonstrated better tolerance under severe stress, while 'Pyrodwarf' and 'Louise Bonne' were more effective under moderate stress conditions.