Effects of aquatic weed removal on freshwater pearl mussels and juvenile salmonids in the River Spey, Scotland

Objective: To investigate the bioactive components of an invasive aquatic weed, Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms vegetative parts by using Gas Chromatography-Mass Spectrometer (GC-MS).Methods: The chemical compositions of the ethanol extract of whole plant Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms was investigated using Agilent Technologies GC-MS (GC-7890A, MS 5975C).Results: The results of GC-MS analysis of the ethanolic extract revealed the existence of 28 phytochemical compounds in Pistia stratiotes L. n-Hexadecanoic acid,-11-Hexadecenoic acid, ethyl ester, Hexadecanoic acid, ethyl ester, Octadecanoic acid, ethyl ester, 2-Cyclopenten-1-one, 5-hydroxy-2,3-dimethyl, L-Glutamine, 2-Pentadecanone, 6,10,14-trimethyl, Linolelaidic acid, methyl ester, 9,12,15-Octadecatrienoic acid, methyl ester,(Z,Z,Z), Nonadecane, 12,15-Octadecadiynoic acid, methyl ester, Hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl)ethyl ester, Diisooctyl phthalate, Docosanoic acid, ethyl ester, Stigmasterol, Bis(2-ethylhexyl) phthalate, 1-Monolinoleoylglycerol trimethylsilyl ether, Ethyl iso-allocholate are the major compound.The ethanolic extract of Eichhornia crassipes (Mart.) Solms contains 43 phytochemical compounds of high and low molecular weight n-Hexadecanoic acid, E-11-Hexadecenoic acid, ethyl ester, Palmitic acid, Phytol, 9,12,15-Octadecatrienal, 9,12-Octadecadienoic acid, ethyl ester, Linolenic acid, ethyl ester, Stearic acid, ethyl ester, Hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl)ethyl ester, α-Glyceryl linolenate, 1-Monolinoleoylglycerol trimethylsilyl ether, Linoleic acid, 2,3-bis-(O-TMS)-propyl ester, Stigmasterol, Linolelaidic acid, methyl ester, 9,12,15-Octadecatrienoic acid, ethyl ester, (Z,Z,Z), Ethyl iso-allocholate, Cholesta-22,24-dien-5-ol, 4,4-dimethyl are the major compounds.These results indicates Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms possess potent antioxidant, anti-inflammatory, anticancer, antitumour, antiarthritic, cancer preventive, antibacterial effects so can be recommended as a plant of phytopharmaceutical importance.Conclusion: The ethanol extract of Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms proves as a potential source of bioactive compounds of pharmacological importance.

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Critical time for weed removal in glyphosate-resistant soybean as influenced by preemergence herbicides

Weed Technology ◽

10.1017/wet.2019.18 ◽

2019 ◽

Vol 33 (03) ◽

pp. 393-399 ◽

Cited By ~ 5

Author(s):

Stevan Z. Knezevic ◽

Pavle Pavlovic ◽

O. Adewale Osipitan ◽

Ethann R. Barnes ◽

Clint Beiermann ◽

...

Keyword(s):

Field Experiments ◽

Critical Time ◽

Growing Season ◽

Control Programs ◽

Main Plot ◽

Repeated Use ◽

Sites Of Action ◽

Alternative Sites ◽

Preemergence Herbicides ◽

Weed Removal

AbstractWidespread and repeated use of glyphosate resulted in an increase in glyphosate-resistant (GR) weeds. This led to an urgent need for diversification of weed control programs and use of PRE herbicides with alternative sites of action. Field experiments were conducted over a 4-yr period (2015 to 2018) across three locations in Nebraska to evaluate the effects of PRE-applied herbicides on critical time for weed removal (CTWR) in GR soybean. The studies were laid out in a split-plot arrangement with herbicide regime as the main plot and weed removal timing as the subplot. The herbicide regimes used were either no PRE or premix of either sulfentrazone plus imazethapyr (350 + 70 g ai ha−1) or saflufenacil plus imazethapyr plus pyroxasulfone (26 + 70 + 120 g ai ha−1). The weed removal timings were at V1, V3, V6, R2, and R5 soybean stages, with weed-free and weedy season-long checks. Weeds were removed by application of glyphosate (1,400 g ae ha−1) or by hoeing. The results across all years and locations suggested that the use of PRE herbicides delayed CTWR in soybean. In particular, the CTWR without PRE herbicides was determined to be around the V1 to V2 (14 to 21 d after emergence [DAE]) growth stage, depending on the location and weed pressure. The use of PRE-applied herbicides delayed CTWR from about the V4 (28 DAE) stage up to the R5 (66 DAE) stage. These results suggest that the use of PRE herbicides in GR soybean could delay the need for POST application of glyphosate by 2 to 5 wk, thereby reducing the need for multiple applications of glyphosate during the growing season. Additionally, the use of PRE herbicides could provide additional modes of action needed to manage GR weeds in GR soybean.

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Modeling the Competitive Effect of Euphorbia dracunculoides and Astragalus sp. in Zero Input Rainfed Chickpea

Planta Daninha ◽

10.1590/s0100-83582018360100021 ◽

2018 ◽

Vol 36 (0) ◽

Author(s):

R.M. IKRAM ◽

A. TANVEER ◽

R. MAQBOOL ◽

M.A. NADEEN

Keyword(s):

Protein Content ◽

Critical Period ◽

Field Experiments ◽

Seed Protein ◽

Yield Loss ◽

Seed Protein Content ◽

Yield Losses ◽

Competition Period ◽

Crop Competition ◽

Weed Removal

ABSTRACT: Brown chickpea (Cicer arietinum L.) is one of the two chickpea types grown in Pakistan and other countries. The critical period for weed removal in a rainfed chickpea system is an important consideration in devising weed management strategies. Field experiments were conducted in the winter season of 2011 and 2012 to determine the extent of yield loss with different periods of weed crop competition. Seven weed crop competition periods (0, 45, 60, 75, 90, 105 and 160 days after sowing - DAS) were used to identify the critical period for weed removal in rainfed chickpea. Experimental plots were naturally infested with Euphorbia dracunculoides and Astragalus sp. in both years. Individual, composite density and dry weights of E. dracunculoides and Astragalussp. increased significantly with an increase in the competition period. However, yield and yield-contributing traits of chickpea significantly decreased with an increase in the competition period. Chickpea seed yield loss was 11-53% in different weed crop competition periods. Euphorbia dracunculoides and Astragalus sp. removed 39.9 and 36.9 kg ha-1 of N, 9.61 and 7.27 kg ha-1 of P and 38.3 and 36.9 kg ha-1 of K, respectively. Season long weed competition (160 days after sowing) resulted in 19.5% seed protein content compared with 24.5% seed protein content in weed-free chickpea. A Logistic equation was fitted to yield data in response to increasing periods of weed crop competition. The critical timing of weed removal at 5 and 10% acceptable yield losses were 26 and 39 DAS, respectively. The observed critical period suggests that in rainfed chickpea, a carefully timed weed removal could prevent grain yield losses.

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