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Light quantity (photosynthetic photon flux density, PPFD) and quality (red:far-red ratio, R:FR) may affect phenological development of weed species growing under a crop canopy. An indoor study was conducted to quantify the effects of incident PPFD and R:FR on development and dry matter accumulation of redroot pigweed (Amaranthus retroflexus L.). Pigweed was grown in growth cabinets from the one-leaf stage to the initiation of seed set under three different PPFD/R:FR treatments: (i) high PPFD (550 p. µmol [m.sup.-2] [s.sup.-1]) and high R:FR (1.4) (HH), (ii) low PPFD (180 µmol [m.sup.-2] [s.sup.-1]) and high R:FR (1.4) (LH), and (iii) low PPFD (180 µmol [m.sup.-2] [s.sup.-1]) and low R:FR (0.8) (LL). The experiment was undertaken at 12- and 16-h daylengths with three replications. Rate of leaf appearance (RLA) was accelerated with an increase in PPFD (HH vs. LH) at both daylengths. The FR enrichment (LL) negated the effect of low PPFD on RLA under the 12-h but not under the 16-h daylength. Low PPFD delayed the occurrence of floral primordia, flowering and initiation of seed set. Plant height was a result of the complementary effects of PPFD and R:FR. Total dry matter accumulation and partitioning, with the exception of dry matter accumulation to the stem, were influenced by PPFD only. Results of this study show that both light quality and quantity influence the phenology of pigweed., REDROOT PIGWEED is a common weed in many agricultural areas (Weaver, 1984; Horak and Loughin, 2000), and its presence can severely reduce yields of various crops (Weaver and McWilliams, 1980). [...]

To select and introduce the best rapeseed genotypes under withholding irrigation, two field experiments were carried out in seasons 2015–2016 and 2016–2017 in Iran. Factorial arrangement of treatments was set up as RCBD with three replications. The experiment factors were two irrigation treatments (normal irrigation during the growing season and withholding irrigation from silique setting stage until the end of the growing season) and 17 genotypes of rapeseed. Grain yield, oil content and fatty acid contents were measured. The results revealed that oleic acid (62.15%) was the highest followed by linoleic (19.28%), linolenic (5.65%), palmitic (5.24%) and stearic acids (2.44%). ODR (oleic desaturation ratio) and LDR (linoleic desaturation ratio) were significantly affected by genotypes and irrigation treatments. The biosynthetic pathway of fatty acids affected by drought stress. This means that linoleic acid increases under withholding irrigation condition, while linolenic acid decreases in such a water deficit stress condition. The highest performance of qualitative and quantitative was detected in HL3721 genotype due to high values of grain yield (3892.45 kg ha−1), oil content (437.05 g kg−1), unsaturated fatty acids (87.63%) and low values of saturated fatty acids (7.98%), and it could be used under withholding irrigation in arid and semi-arid climates. [ABSTRACT FROM AUTHOR]

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Information regarding the evaluation of priming treatments on germination traits of Dracocephalum moldavica L. varieties is not available. Therefore, this assay was conducted during 2013 in Islamic Azad University of Sanandaj located in Kurdistan province of Iran. Twelve treatments resulted from a factorial combination of six priming method (factor A) and two varieties of moldavian dragonhead (factor B), arranged in a completely randomized design replicated three times. Factor A included 50 mg L-1 Salicylic acid (SA), 100 mg L-1 SA, 50 mg L-1 Ascorbic acid (AsA), 100 mg L-1 AsA, hydro-priming and control. Factor B included Kurdish landrace and SZK1 cultivar. Results showed that the highest and lowest emergence percentages were 90.1% in Kurdish SA50 and 52.8% in SZK1 AsA100 treatments, respectively. Hydro priming treatment increased the emergence rate index more than 100 mg L-1 SA, 100 mg L-1 AsA and control treatments. The highest shoot weight was 9.41 mg for Kurdish SA50 treatment and the lowest length, 1.24 mg was attributed to SZK1 control treatment. The highest (6.56 mg) and lowest (1.74 mg) radicle weight were observed in Kurdish-hydro-priming and SZK1-AsA100 treatments. The Kurdish landrace showed a favorable germination condition compared to SZK1 cultivar. [ABSTRACT FROM AUTHOR]

The effect of irrigation regimes and N rates on corn (Zea mays L.) yield and redroot pigweed (Amaranthus retroflexus L.) growth in sandy soils is not completely understood. Therefore, field experiments were conducted in a semiarid region of Iran in 2010 and 2011 to determine the influence of N rates and irrigation regimes on corn and redroot pigweed leaf area index (LAI), dry matter and grain yield, N uptake, irrigation water productivity (IWP) and N leaching loss. The experiment was conducted using a randomized complete-block design with a split-factorial arrangement of treatments in four replicates. The main plots were subjected to either a low (L) or a full (F) irrigation regime. The subplots were arranged in a factorial scheme with four N rates (0, 150, 300, and 450 kg N ha-1) and two levels of redroot pigweed interference with corn (weed free, CW0; and weedy, CW1). The results indicated that the more N was applied, the higher were corn grain yield losses in both irrigation regimes due to weed interference. The difference in corn grain yield between CW0F and CW1F treatments was 400 and 1800 kg ha-1 at N0 and N450 levels, respectively. In contrast, the difference between CW0L and CW1L reached 300 and 800 kg grain ha-1 at N0 and N450 levels, respectively. Based on the information gained in this study, we do not recommend increasing inputs (water and N), especially in sandy soils, to diminish the redroot pigweed/corn competition. [ABSTRACT FROM AUTHOR]

Background: Feverfew (Tanacetum parthenium L.) is a herbal plant that has anti- septic, anti-microbial, anti-parasitic and anti-inflammatory effects. The main objective of this study is to evaluate the antimicrobial effect of shoot essential oil (essential oil of the aerial parts of the plant) of the feverfew on a number of microorganisms including gram-negative and gram-positive bacteria, filamentous fungi and yeasts. Materials and Methods: In this empirical study, plant samples were collected at the full blooming stage. Shoot essential oil was extracted using hydro-distillation technique and Clevenger apparatus. Components of the extract were identified using GC and GC/MS apparatus and its antimicrobial properties were evaluated using diffusion in Agar method (disk diffusion) and dilution in the well (Micro-broth dilution)6T. Results: Among 35 compounds identified in the essential oil of the feverfew, camphor (45%), 8Tchrysanthenyl acetate8T (21.5) and camphene (9.6%), were the main components respectively. Essential oil showed very good antifungal effect which was stronger than its antibacterial effect. Gram-negative bacteria were less sensitive to the essential oil than gram-positive bacteria. The mean diameter of inhibition zone, in the bio-assessment of the effect of feverfew essential oil on gram-positive bacteria and fungi was respectively more than the effect of vancomycin and amphotericin B and this effect on gram-negative bacteria was less than the effect of gentamicin. This effect is attributed to the high value of camphor, chrysanthenyl acetate and camphene found in the essential oil. Conclusion: Feverfew essential oil could be utilized as a sound and harmless substitute for the antibiotics. [ABSTRACT FROM AUTHOR]

Salinity and water-deficit stress reduce yield in agricultural crops. On the other hand, seed germination is critical in seedling establishment and subsequent plant growth. Therefore, the present investigation was carried out to evaluate the effects of chitosan (Ch) concentrations (0% [control], 0.05%, 0.1%, 0.2%, 0.4%, 0.5%, 1%, 2%, and 3%) on the tolerance of safflower (Carthamus tinctorius L.) to different osmotic potentials (0, −0.4, −0.8, and −1.2 MPa). Induced osmotic potential significantly decreased germination percentage, germination index and rate, length and weight of root and shoot, and protein content. Proline content, malondialdehyde content (MDA), and catalase (CAT) and peroxidase (POX) activity increased when osmotic potential was increased to −0.8 MPa. Under unstressed conditions (0 MPa), there were no significant differences in germination percentage among different concentrations of chitosan, whereas MDA content, CAT, and POX activity were increased by low concentrations of chitosan (0.05%–0.4%). With increasing water-deficit stress, low concentrations of chitosan increased germination percentage but decreased MDA and proline contents and CAT and POX activity. Thus, it could be concluded that low concentrations of chitosan exhibited positive effects on water-deficit alleviation through the reduction of enzyme activity. Therefore, chitosan should be an effective biostimulator to enhance seedling growth and plant tolerance to oxidative stress conditions, especially under conditions of drought stress. [ABSTRACT FROM PUBLISHER]