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Phytotoxic Effects of Leaf Leachates of Invasive Weeds Cosmos sulphureus and Xanthium strumarium on Agricultural Crops

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Many invasive weeds are known to create their deleterious effects on biological ecosystems and also rhizosphere soils. Weeds such as Cosmos and Xanthium have their existence near agricultural crops fields. Such weeds grow in abundance, releasing specific allelochemicals which have adverse effect on germination rate, physiological patterns and reproduction of crop plants. In present work, allelopathic effects of leaf leachates of Cosmos and Xanthium were observed on seed germination and seedling growth of Triticum aestivum, Vigna radiata and Trigonella foenum-graceum like crops. Seed germination was inhibited at higher concentration at 6% while lower concentrations showed stimulatory effect on Mungbean and Fenugreek from 1%-4% concentrations. But seed germination percentage of Vigna and Trigonella showed 70% and 60% growth in response to leaf leachates of Cosmos at 6% concentration. Triticum showed total inhibition of 40% to both leaf leachates. The qualitative phytochemical analyses showed presence of alkaloids, phytosterols, phenols, tannins and flavonoids. GCMS and IR studies revealed presence of major constituents such as esters, ethers, anhydride and polyalcohols. Cosmos and Xanthium showed the characteristic FTIR fingerprinting regions of various functional groups such as –OH, carbonyl, anhydride, ester and amides. The variations in phytochemicals of these invasive might be attributed to response of the plants to different environmental stresses.
BIOSCIENCES BIOTECHNOLOGY RESEARCH ASIA, December 2018. Vol. 15(4), p. 821-832
Published by Oriental Scientific Publishing Company © 2018
This is an Open Access article licensed under a Creative Commons license: Attribution 4.0 International (CC-BY).
*Corresponding author E-mail:
Phytotoxic Effects of Leaf Leachates of Invasive
Weeds Cosmos sulphureus and Xanthium strumarium
on Agricultural Crops
Nivedita Ghayal1*, Megha Biware2 and Pallavi Gharpure3
1Department of Botany, AbasahebGarware College, Pune-04, MS., India.
2Department of Chemistry,AbasahebGarware College, Pune-04, MS., India.
3Department of Biodiversity, AbasahebGarware College, Pune-04, MS., India.
*Corresponding author E-mail: gnivedita_ghayal@rediffmail.com
http://dx.doi.org/10.13005/bbra/2691
(Received: 13 November 2018; accepted: 12 December 2018)
Many invasive weeds are known to create their deleterious effects on biological
ecosystems and also rhizosphere soils. Weeds such as Cosmos sulphureusCav. and Xanthium
strumariumL. have their existence near agricultural cropfields. Such weeds grow in
abundance, releasing specific allelochemicals which have adverse effect on germination rate,
physiological patterns and reproduction of crop plants. In present work, allelopathic effects
of leaf leachates of Cosmos and Xanthium were observed on seed germination and seedling
growth of Triticumaestivum, Vignaradiata and Trigonellafoenum-graceumlike crops. Seed
germination was inhibited at higher concentration at 6% while lower concentrations showed
stimulatory effect on Vignaradiata and Trigonellafoenum-graceumfrom 1%-4% concentrations.
But seed germination percentage of Vigna and Trigonellashowed 70% and 60% growth in
response to leaf leachates of Cosmos at 6% concentration. Triticumshowed total inhibition
of 40% to both leaf leachates. The qualitative phytochemical analyses showed presence of
alkaloids,phytosterols, phenols, tannins and flavonoids. GCMS and IR studies revealed presence
of major constituents such as esters, ethers, anhydride and polyalcohols. Cosmos and Xanthium
showed the characteristic FTIR fingerprinting regions of various functional groups such as –OH,
carbonyl, anhydride, ester and amides. The variations in phytochemicals of these invasive
might be attributed to response of the plants to different environmental stresses.The rate of
growth of these invasive weeds and their over-dominance is very difficult to control but their
huge biomass can be used in sustainable development.
Keywords: Allelopathy,Asteraceae, GC-MS, IR Spectroscopy,Phytochemicals.
Allelopathy majorly is described as any
direct or indirect effect of one plant on another
plants, animals or microorganismsthrough the
production of chemical compounds that escape
into the environment and inuence the growth
and development(Bezuidenhout; 2012, Sangeetha
and Bhaskar; 2015, Riceand Pancholy; 1974).
This phenomenon encompasses many aspects
of physiology, biochemistry, observations and
interactions occurring in nature. The effect of any
alien or exotic species can cause loss of ecosystem
balance, affecting its functioning incurring the loss
of biodiversity through release of allelochemicals
(Inderjit, 2005). Such plants can have stimulatory
822 GHAYAL et al., Biosci., Biotech. Res. Asia, Vol. 15(4), 821-832 (2018)
or inhibitory effectson crops. The secondary
metabolites from such plants that are considered
as allelochemicals do not have much physiological
function in metabolism of plants. Theyserve
only as agents of plant-plant competition during
establishment in new ecosystem along with plant-
microbe symbioses.
Exotic invasive weeds are non-natives
due to their occurrence in different geographical
regions. These invasive plants species have several
motives for their successful establishment such as
faster rate of reproduction, dispersal mechanisms,
potency to establish large populations in short
period of time with adaptive nature resulting
in resource depletion. Such exotic plants show
faster rate of establishment without any human
assistance. Many recent investigations have
shown that invasive plants have changed several
community attributes like species diversity,
richness, species composition and abundance
(Keblawyet al. 2006). Dominance, higher growth
rate throughout the invaded area, high tolerance
towards abiotic environmental factors and also
the allelopathic potential are probable favourable
factors for their sustainability.The researches have
indicated that some plant invaders become much
more dominant in their invaded range than their
native range. Frankel (1999) showed that alien
plants displaced local ora, changed ecosystems
and disturbed the biodiversity. The dominant
plants by forming pure stands/ monothickets
through interactions exhibit allelopathy and such
plants generally are free of predators, parasites
and diseases. They have inuence on the growth
and development of agricultural and biological
ecosystem (Sangeetha and Bhaskar, 2015) through
release of various allelochemicals or ecochemicals.
Allelochemicals are produced in all plant
parts in different concentrations and released in the
environment through leaching, volatilization, root
exudation, decomposition etc.Their concentration
depends on maturity stage of plant as younger
plants are more toxic. Soil and soil factors as biotic
and abiotic components are important in terms of
determining the quality, quantity and availability
of allelochemicals in the vicinity of neighbouring
species (Inderjit, 2005). Concentration of
allelochemicals is density-dependent factor
(Inderjit 2005) present in soil, which shows
changes in the soil characteristics, but to detect
the exact concentrations of allelochemicals in
eld is difcult. It has been reported that even low
concentrations of chemicals can cause signicant
effect on growth and germination of other plants.
Therefore isolation and identication of chemicals
is most signicant part in demonstrating allelopathy
(Inderjit and Dakshini,1994, Inderjitet al. 2005).
According to (Rice, 1984) and Putnam and Tang
(1986) the most widely used standard bioassay
test is the influence of allelochemicals on
germination parameters such as seed germination,
seedling growth, root length and shoot length etc.
under controlled laboratory conditions, which is
undertaken in the present investigation as well. So
also to establish phenomenon of allelobiogenesis,
the assessment of allelochemicals by qualitative
phytochemical analysis, GC-MS and IR methods
was taken on.
Khadakwasla, Mulshi and Paud-
Pirangutareas (18o30’42.30" N, 73o40’49.28" E)
are agricultural elds on Lavasa road. According to
eld observations Cosmos has enormously invaded
from BhugaonuptoMulshi(about 30kms) covering
the whole area along road side edges and rice
crops. Xanthiumalso shows widespread expansion
and has been observed near agricultural crop
elds (Patil 2009). These areas are with moderate
rainfall and have sandy and loamy soil which
is favourable for growth of these two invasive
speciesandcompete with the kharif crops (Patil
2009).Cosmos and Xanthium both are considered
toxic and non-palatable alien weeds unsuitable as
fodder with no certain methods of eradications.
Katrajghat ranges (18027’27.12"N, 73052’3.89"E)
was another area selected for the study and found to
be invaded greatly by the same two weeds Cosmos
and Xanthium.
Cosmos sulphureus Cav. (Asteraceae)
a native of Mexico, was accidentally introduced
to Indian sub-continent. This annual, herbaceous,
invasive weed, with non-fragrant owers, is found
gregariously growing on elds and hedges of crops,
wastelands and marshy places. It can grow upto
height of 8-10 feet, that can create shadow for short
heighted crops inhibiting their light harvesting
mechanism.It is a moderate reseeder, growing
onsandy and loamy soils favor its profuse seed
germination.
Xanthium strumarium L. (Asteraceae),a
perennial shrub, native of North America and
823
GHAYAL et al., Biosci., Biotech. Res. Asia, Vol. 15(4), 821-832 (2018)
Eurasia. It germinates by reseeding itself. The
plant seeds can sustain very harsh environmental
conditions, by remaining dormant for about 2-10
years. Young seedlings of Xanthium release toxic
chemicals that can inhibit germination and prove
fatal to neighbouring plants. Specic environmental
conditions such as optimum oxygen, high moisture
and direct sunlight with moist, loamy or sandy
soil are necessary requirements for its successful
growth. Seeds and seedlings are highly toxic to
mammalian herbivores.
Mungbean (Vignaradiata L) and
Fenugreek/ Methi (Trigonellafoenum-
graceumL.)— (Both Members of Fabaceae),
cultivated crops throughout India and also Wheat
(Triticumaestivum L)—Wheat (Poaceae), a major
cultivated staple food crop were used for standard
seed germination bioassay studies.
MATERIALS AND METHODS
Collection of plant materials
Fresh leaves of Cosmos and Xanthium
at maturity stage were collected during monsoon
period (July-October2016, 2017) along agricultural
elds from selected ruralareas like Khadakwasla,
Mulshi and Paud-Pirangutareas, Lavasa area and
Katrajghat area.
Preparation of leaf leachates
Fresh leaves were air shade dried, ground
in a mixer to form a homogeneous powder and
stored in air tight bottles. 10 g. of dried powders
of Cosmos and Xanthium were mixed with 100
ml water in 250 ml beakers separately and kept in
dark for 24 hours at room temperature. They were
ltered through muslin cloth (size 2mm) to obtain
aqueous leachates (10%). From this stock solution
different concentrations were prepared (1% - 6%
v/v) by making dilutions with distilled waterand
were usedfor seed germination bioassays.
The seeds of three crop plants Triticum,
Trigonella, Vignawere procured from authentic
source. Healthy seeds of wheat, fenugreek
(methi) and mungbean were surface sterilized
with 0.02% aqueous Hgcl2 (Mercuric chloride)
for two minutes. Then the seeds were thoroughly
washed with distilled water. Petri-plates(9 cm
dia.) were sterilized with 70% alcohol and lined
with germination paper moistened with different
concentrations of leaf leachates of Cosmos and
Xanthium. The seeds were placed in these petri-
plates for germination. Experiments were carried
out twicein laboratory conditions in triplicates
with control of distilled water. Petri-plates
were monitored daily and germination papers
were moistened after 2-3 days with solutions of
respective concentrations. After 8 days germination
parameters such as number of seeds germinated
(germination %), root length, shoot length, root :
shoot ratio, vigour index were studied (Gupta et
al; 1996).
Solventextraction method for phytochemicals
analyses
Powdered dried leaf materials of Cosmos
and Xanthium weighing about 5mg was mixed with
Ethanol solvent and allowed to homogenize for
3-4 hrs approximately. The mixtures were ltered
through muslin cloth and ltrate was further tested
for phytochemical analysis.
Detection of allelochemicals by GC-MS methods
Working procedure for test sample
was as follows - 10 ppm solution was prepared
in ethanol for Cosmos and Xanthium dry leaf
powders separately. The solutions were ltered
through 0.2µ nylon lter and ltrate sample was
injected. GC-MS method- Make model: Agilent
Technologies 7000 GC/MS Triple Quad The 7000
Series Triple Quad GC/MS is a standalone capillary
GC detector for use with the Agilent 7890A Series
gas chromatograph. Inbuilt Software installed for
qualitative analysis of MS is Mass Hunter.
Detection of allelochemicals by IR method
Jasco FTIR (V-5300) model: Dry
leaf powders of Cosmos and Xanthium were
homogenised in mortar – pestle in a palette along
with Potassium bromide powder (KBr) and about
1% of mixture was lled in cuvette. Control or
Blank was run with Pottassium bromide (KBr) only
followed with samples respectively. Wavelength
from 400-4000 nm is generally an installed range
for the detection of compound. Graph is overlay
with API (Active Pharmacopeia Ingredients)
standards to identify the peaks.
Statistical analysis
Calculations of germination parameters
were carried out as average of three determinants
along with standard deviation. Analysis of data
results were subjected to correlation to nd out
824 GHAYAL et al., Biosci., Biotech. Res. Asia, Vol. 15(4), 821-832 (2018)
Plate 1. Satellite image of selected study sites
Plate 2. Seed germination bioassay by petriplate method
Fig. 1. Effect of leaf leachates of Xanthium on seed germination of Wheat, Mungbean and Fenugreek (Methi)
overall effect of increasing concentrations on
germination % and graphs were performed in SPPS
software.
RESULTS AND DISCUSSION
Cosmos and Xanthium are invasive weeds,
mainly found in the areas which are altered due
to great human disturbances such as changes in
land-use activities like agriculture, construction
of road etc. Previous studies have revealed that
these invasive weeds have deleterious effects on
natural habitats like changes in soil composition
due to release of allelochemicals which makes
it unsuitable for growth of indigenous plants /
crops. Different cropplants show different levels
of tolerance towards allelochemicals which may
be either beneficial or deleterious. Therefore
to evaluate the effects of allelochemicals on
germination and growth of cropseeds, standard
laboratory germination bioassay method was
825 GHAYAL et al., Biosci., Biotech. Res. Asia, Vol. 15(4), 821-832 (2018)
Fig. 2. Effect of leaf leachates of Cosmos on seed germination of Wheat, Mungbean and Fenugreek(Methi)
considered as most important part of this study
(Friedman 1995; Gogoiet al. 2002)
Seed germination and seedling growth are
two focal parameters used in allelopathic bioassays
(Rice, 1984), since the plant is considered to
be most susceptible in its growth stage. The
latter shows effective response to presence of
allelochemicals as elongation of root. It is natural
deciding factor that shows positive or negative
effect on rate of germination.
Seed germination studies
Germination percentage
Leaf leachates of Cosmos and Xanthium
inhibited the seed germination with increased
concentrations in all selected crops with varying
degree of response. For Xanthium5% and 6%
concentrations showed signicant changes in seed
germination for all 3 crops, Wheat, Mungbean
and Fenugreek whereas at lower concentrations
(1%) seed germination was at par with control
forXanthium. Cosmos in comparison with Xanthium
showed inhibition at 5% to Wheat whereas for
Mungbean and Fenugreek LC50 was observed at 6%
concentration. The graphs (Figures 1 and 2) showed
a gradual decrease in germination for Cosmos as
compared to Xanthium. Changing response of
different plants may be due to concentration of
inhibitory chemicals and mechanisms of inhibitory
effects. The wheat seeds were found to be more
receptive with respect to inhibition of germination
than mungbean and Fenugreek cropseeds.
Effects of Cosmos and Xanthium leaf leachates
on seed germination of Triticumaestivum(Wheat)
Triticum showed minimum i.e. (40%)
germination at 6% concentration for both Xanthium
and Cosmos. At 1% concentration effect was
at par with control. The inhibitory effects were
observed in all germination parameters with
increasing concentrations of leachates. The effect
of leachates on root length was similar to shoot
length for both Cosmos and Xanthium with minimal
differences. Shoot length was inhibited (9.2 ± 0.60)
over control (12.2 ± 0.92) to Cosmos leachate
at 1%concentration whereas effect of Xanthium
leachates at 1% on germination was similar with
that of control and it reduced to 90% of germination
at 2% to 4% of leachates concentrations. Root:
shoot ratio remained consistent for concentration
upto 6% for Cosmos but it showed increasing
trend with Xanthium. Vigor index showed drastic
reduction with increasing concentrations as shown
in both the Tables1 and 2.
Effects of Cosmos and Xanthium leaf leachates
on seed germination of Vignaradiata(Mungbean)
Germination was observed to be inhibitory
at 6% for Xanthium (40%) but it remained upto
(70%) for 6% concentration for Cosmos. Leaf
leachates of Cosmos probably had stimulatory
effect on germination percentage, root and shoot
length at all concentrations as concentrations
increased (Table 3). Shoot length was increased at
1% concentration (11.03cm) than that of control
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GHAYAL et al., Biosci., Biotech. Res. Asia, Vol. 15(4), 821-832 (2018)
Table 1. Effect of leaf leachates of Cosmos on seed germination of Triticumaestivum
Conc. Of Germination % Root length Shoot length R:Sratio Vigor index
leachates
Control 100%±0.07 14.2±1.06 12.2±0.92 1.16±0.09 1220±91.50
1% 100%±0.06 7.2±0.47 9.2±0.60 0.78±0.05 920±59.80
2% 90%±0.05 7.06±0.39 7.7±0.42 0.91±0.05 693±29.64
3% 85%±0.08 6.6±0.63 8.4±0.80 0.78±0.07 714±55.86
4% 70%±0.07 6.73±0.67 7.8±0.78 0.86±0.09 546±54.60
5% 60%±0.05 3.1±0.25 3.3±0.26 0.93±0.07 198±15.84
6% 40%±0.03 2.8±0.18 2.7±0.18 1.03±0.07 108±91.50
Table 2. Effect of leaf leachates of Xanthium on seed germination of Triticumaestivum
Conc. Of Germination % Root length Shoot length R:Sratio Vigor index
leachates
Control 100% ±0.07 12.17 ±0.91 12.17 ±0.91 1 ± 0.07 1217 ±91.27
1% 100% ±0.06 10.83 ±0.70 11.03 ±0.72 0.98 ±0.06 1103 ±71.69
2% 90% ±0.05 9.77 ±0.54 10.23 ±0.56 0.95 ±0.05 920.7 ±50.64
3% 90% ±0.09 9.4 ± 0.89 8.87 ±0.84 1.05 ±0.10 798.3 ±75.84
4% 90% ±0.09 8.83 ±0.88 8.67 ±0.87 1.01 ±0.10 780.3 ±78.03
5% 50% ±0.04 5.07 ± 0.41 3.73 ±0.30 1.35 ±0.11 186.5 ±14.92
6% 40% ±0.03 3.67 ±0.24 1.63 ±0.11 2.25 ±0.15 65.2 ±5.30
Table 3. Effect of leaf leachates of Cosmos on seed germination of Vignaradiata
Conc. Of Germination % Root length Shoot length R:Sratio Vigor index
leachates
Control 100% ±0.07 7.1 ±0.53 9.6 ±0.72 0.73 ±0.05 960 ±72.00
1% 100% ±0.06 6.8 ±0.44 11.03 ±0.72 0.61 ±0.04 1103 ±71.69
2% 90% ±0.05 5.33 ±0.29 7.4 ±0.41 0.72 ±0.04 666 ±36.63
3% 80% ±0.08 5.2 ±0.49 7.06 ±0.67 0.73 ±0.07 564.8 ±53.66
4% 80% ±0.08 4.7 ±0.47 6.9 ±0.69 0.68 ±0.07 552 ±55.20
5% 70% ±0.06 3.5 ±0.28 5.3 ±0.42 0.66 ±0.05 371 ±29.12
6% 70% ±0.05 3.46 ±0.22 5.2 ±0.34 0.66 ±0.04 364 ±23.66
(9.6 cm) in response to leachate of Cosmos. Though
Xanthium showed similarlittle increase in shoot
length at 1% (8.07cm) as compared with control
(8.17cm), but as concentration increases there was
reduction in shoot length. Root: shoot ratio showed
a constant trend of increase from control to 6%
concentration for Xanthium but a reduced trend
in case of Cosmos. Root: Shoot ratio is a highly
dependent factor on length of root and shoot of
plant and also dependent on concentrations of
leachates. Vigour index showed gradual decrease
over control as affected by leachates of Xanthium
and Cosmos.
Effects of Cosmos and Xanthium leaf leachates
on seed germination of Trigonellafoenum-
graceum(Methi)
Both the weedsCosmos and Xanthium
showed inhibitory effects on germination percentage
for Fenugreek 60% and 50% respectively over
control. Minimum effect was observed for leachate
concentrations of Cosmos on germination. LC50 for
Xanthium was attained at 6% concentration only.
Emergence of shoot length was drastically inhibited
at 5% (2.23cm) and 6% (1.07cm) concentrations
of leaf leachates of Xanthium as compared to
Cosmos. Cosmos showed minimal inhibitory effect
827 GHAYAL et al., Biosci., Biotech. Res. Asia, Vol. 15(4), 821-832 (2018)
Table 4. Effect of leaf leachates of Xanthium on seed germination of Vignaradiata
Conc. Of Germination % Root length Shoot length R:Sratio Vigor index
leachates
Control 100% ±0.07 4.57 ±0.34 8.17 ±0.61 0.57 ±0.04 817 ±60.53
1% 90% ±0.06 7.93 ±0.52 8.07 ±0.52 0.98 ±0.06 726.3 ±47.21
2% 90% ±0.05 7.57 ±0.42 5.63 ±0.31 1.34 ±0.07 506.7 ±27.87
3% 80% ±0.08 7.3 ±0.69 5.2 ±0.49 1.4 ±0.13 416 ±39.52
4% 60% ±0.06 2.93 ±0.29 4.07 ±0.41 0.71 ±0.07 244.2 ±24.42
5% 50% ±0.04 0.97 ±0.08 3.53 ±0.28 0.27 ±0.02 176.5 ±14.12
6% 40% ±0.03 0.93 ±0.06 1.73 ±0.11 0.53 ±0.03 69.2 ±60.53
Table 5. Effect of leaf leachates of Cosmos on seed germination of
Trigonellafoenum-graceum
Conc. Of Germination % Root length Shoot length R:Sratio Vigor index
leachates
Control 100% ±0.07 5.6 ±0.42 6.3 ±0.47 0.88 ±0.07 630 ±47.25
1% 100% ±0.06 3.7 ±0.24 5.1 ±0.33 0.72 ±0.05 510 ±26.52
2% 90% ±0.05 3.26 ±0.18 4.8 ±0.26 0.67 ±0.04 432 ±21.12
3% 80% ±0.08 2.9 ±0.28 4.66 ±0.44 0.63 ±0.06 372.8 ±35.43
4% 70% ±0.07 2.4 ±0.24 4.1 ±0.41 0.58 ±0.06 287 ±28.90
5% 70% ±0.06 2.6 ±0.21 4.2 ±0.34 0.61 ±0.05 294 ±23.84
6% 60% ±0.04 2.03 ±0.13 3.86 ±0.25 0.41 ±0.03 231.6 ±15.05
Table 6. Effect of leaf leachates of Xanthium on seed germination of
Trigonellafoenum-graceum
Conc. Of Germination % Root length Shoot length R:Sratio Vigor index
leachates
Control 100% ±0.07 3.33 ±0.25 5.4 ±0.41 0.61 ±0.05 540 ±40.50
1% 100% ±0.06 4.8 ±0.31 5.17 ±0.34 0.92 ±0.06 517 ±33.60
2% 100% ±0.06 4.03 ±0.22 4.6 ±0.25 0.87 ±0.05 460 ±25.30
3% 100% ±0.09 3.97 ±0.38 4.07 ±0.39 0.97 ±0.09 407 ±38.66
4% 80% ±0.08 3.6 ±0.36 3.9 ±0.39 0.92 ±0.09 312 ±31.20
5% 70% ±0.06 3.27 ±0.26 2.23 ±0.18 1.46 ±0.12 156.1 ±12.49
6% 50% ±0.03 2.47 ±0.16 1.07 ±0.07 2.3 ±0.15 53.5 ±3.48
on all measurable parameters. Root: shoot ratio
showed reduction for Cosmos over control to 6%
concentration. But Xanthiumshowed increase in
root length though shoot growth was hampered.
Reduction in vigor index upto70% from control
to 5% and 6% for Cosmos was observedbut
in Xanthium reduction of vigor index was
concentration dependent from 5% to 6%. Values
are mentioned in tables5 and 6 respectively.
DISCUSSION
Allelopathic plants are described as
alien, invasive weeds from different geographical
areas. They establish successfully through
release of various allelochemicals, according to
the contiguous environmental stress conditions.
Dominance, higher growth rate and adaptability
to existing environments are some of the attributes
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GHAYAL et al., Biosci., Biotech. Res. Asia, Vol. 15(4), 821-832 (2018)
Table 7. Functional group peaks from GC-MS study of Cosmos sulphureus
Sr. Retention Time IUPAC Molecular Molecular
No formula Weight
1. 26.334-27.049 Carnegine C13H19NO2 221
2. 17.559-18.553 Malonic acid,2-formamido-2{4-(4-hydroxy- C20H24N2O6 388
3-methyl-2-butenyl)indol-3}methyl-dimethyl ester
N-{5-(3-hydroxy-2-methylpropenyl)-1,3,4, C18H22N2O2 298
5-tetrahydrobenzo(cd) indol-3-yl}-N-methylacetamide
3. 26.250-27.001 Carnegine C13H19NO2 221
Hexanal,(2,4-dinitrophenyl) hydrazone C12H16N4O4 280
(2-Methyl-3-nitrophenyl) methanol, C16H14F5NO3Si 391
dimethylpentau-orophenylsiyl ether
Table 8. Functional group peaks from GC-MS study of Xanthium strumarium
Sr. Retention IUPAC Molecular Molecular
No Time formula
weight
1. 8.921 Salmeterol C25H37NO4 415
2. 26.581 Tricylotetradecan-6-one,4-ethenyl-3-hydroxy-2, C20H32O2 304
4,7,14-tetramethyl
3. 8.860 4-Acetyloxyimino-6-6-dimethyl-3-methylsulfany C15H19NO4S2 341
l-4,5,6,7-tetrahydro-benzo(c)thiophene-1-carboxylic
acid methyl ester
8.980 Brnzene,2,3,4,5-tetramethyl-1-(2,3,4,5- C21H28 280
tetarmethyl benzyl)
Corynan-17-ol,18,19-didehydro-10-methoxy C20H26NO2 326
4. 13.996-14.241 Carda-5-20(22)-dienolide,3-(6-deoxy-alpha- C29H42O8 518
L-mannopyranosy)oxy)-14-hydroxy-(3beta)
11-beta,19-Cyclopregn-5-ene-3,20-dione,11- C25H36O5 416
hydroxy-cyclic bis (ethylene acetal )
Carnegine C13H19NO2 227
5. 15.801-16.681 Malonic acid,2-formamido-2{4-(4-hydroxy-3- C20H24N2O6 388
methyl-2-butenyl)indol-3-y}methyl-dimethyl ester
4a-Methyl-1-methylene-1,2,3,4,4a,9,10,10a- C16H20 212
octahydrophenanthrene
Benzeneethanamine,2-uoro-beta,3,4-trihydroxy- C11H16FNO3 229
N-isopropyl
6. 17.524-18.835 Malonic acid,2-formamido-2{4-(4-hydroxy-3- C20H24N2O6 388
methyl-2-butenyl)indol-3-yl) methyl-dimethylester
Benzenamine,4-(1-methylethyl)-N-phenyl C15H17N 211
1,7-di-iso-propylnapthalene C16H2O 212
7. 20.200-20.425 Carnegine C13H19NO 221
9,12,15-Octadecatrienoic acid,2,3-bis{(trimethylsily)oxy} C27H52O4Si2 496
propyl ester
2-Oxo-4-6-diphenyl-3-(4-tolyl)-1,2,3,4-tetrahydropyrimidine C23H20N2O 340
for their successful establishment. Most of the
allelochemicals are secondary metabolites of
plants playing a signicant role as stress tolerant
compounds. Allelo/ ecochemicals present in several
parts of such plants havetheir own mechanisms of
release into environment. They may have inhibitory
or stimulatory effect on growth and germination
of neighboring plants or crops. This effect can be
829 GHAYAL et al., Biosci., Biotech. Res. Asia, Vol. 15(4), 821-832 (2018)
Table 9. FTIR spectral peak values and functional
groups for the leaf extract of Xanthium strumarium
Peak Values Functional groups
Wave number
(cm-1)
3517.52 Free -OH
2923.56 -CHO ( C-H Stretch)
1895.68 C=O of anhydride, ester
1746.23 =CH2, C=O of acid anhydride
1541.81 Aromatic region, N-H for prim and
sec amide
1407.78 Aromatic region
1041.37 C-O-C
437.439 C-N,C-C,C-O
440.665 C-N,C-C,C-O
632.537 Aromatic
525.507 Aromatic
466.689 C-N,C-C,C-O, aliphatic C-I,
422.334 C-N,C-C,C-O
412.692 C-N,C-C,C-O, aliphatic C-I,
327.194 Bending vibration depends on
substitution Pattern
308.555 Bending vibration depends on
substitution Pattern
212.131 Bending vibration depends on
substitution Pattern
159.099 Bending vibration depends on
substitution Pattern
95.4591 Bending vibration depends on
substitution Pattern
Table 10. FTIR spectral peak values and functional
groupsfor the leaf extract of Cosmos sulphureus
Peak Values Functional
Wave number groups
(cm-1)
3639.02 Free -OH
2917.77 -CHO ( C-H Streach )
1656.55 C=C in alkens or Aromatic region,
1425.14 Aromatic region
1014.37 C-O-C(Ethers)
782.958 =C-H(m),CH=CH,
476.331 Aliphatic C-I region.
445.476 Bending vibration depends on
substitution Pattern
431.012 Bending vibration depends on
substitution Pattern
415.585 Bending vibration depends on
substitution Pattern
820.563 =C-H
538.042 -C-X,
501.401 -C-X,
466.689 -C-X,
422.334 Bending vibration depends on
substitution Pattern
411.728 Bending vibration depends on
substitution Pattern
372.194 Bending vibration depends on
substitution Pattern
295.055 Bending vibration depends on
substitution Pattern
282.52 Bending vibration depends on
substitution Pattern
223.702 Bending vibration depends on
substitution Pattern
194.775 Bending vibration depends on
substitution Pattern
159.099 Bending vibration depends on
substitution Pattern
123.422 Bending vibration depends on
substitution Pattern
95.4591 Bending vibration depends on
substitution Pattern
monitoredLeather and Einhellig (2005) through
seed germination bioassay studies by considering
parameters such as germination %, root length
and shoot length. According to Inderjit and Nilsen
(2003) laboratory bioassays and eld studies are
fundamental part of allelopathy research, because
they are fast and repeatable tools for exploring the
potential for different types of interactions.
The study was to evaluate the phytotoxic
effect of such invasive weeds on physiological
growth of cereals and pulses.The allelopathic impact
of leachates or extracts is more harmful to radicle
(Friedman; 1995). The phytotoxicity was directly
proportional to the increasing concentrations
of leachates.Many researchers have shown such
inhibition of seed germination as affected by
leaf leachates of various invasive weeds. 10% of
aqueous leaf extract of Partheniumhysterophorus
has shown total inhibition of Triticumaestivum
(SeerjanaMaharajan et al., 2007). Aqueous
extract and leachate may have different response
towards the germination of Wheat. Preliminary
studies had revealed signicant inhibitory effect
on seed germination and seedling growth of
selected crops from different geographical
regions. The previous studies showed that aqueous
extracts of hearleaf cocklebur (Xanthium) was
effective on crops such as Wheat and Barley
even with low density of presence of weeds
830
GHAYAL et al., Biosci., Biotech. Res. Asia, Vol. 15(4), 821-832 (2018)
(IzzetKadioglu,2004). Cutler and Cole reported
that potassium carboxyactractyloside, a glycoside
isolated from the residues of Xanthium strumarium
L. strongly inhibiting coleoptiles growth of Wheat
(Benyas et al, 2010).
Similar inhibitory effects of aqueous
extracts of Ranunculus arvensis, Sinapisarvensis,
Smilaxaspera were observed with wheat
germination percentage and rate as compared to
inhibitory effects of Cosmos and Xanthium leaf
leachates. The effect of aqueous extracts on root
growth was more than shoot growth(Qasem, 2017).
Different plants showed variable effects on target
species and their responses.
Clerodendruminfortunatumshowed
highest inhibitory effect on Vignaradiataseeds at
100% concentration. And forTrigonellafoenum-
graceum maximum inhibitory effect on germination
was at 100% concentration and in case of
Triticumaestivum and Brassica campestris highest
inhibitory effect started from 75% and 50%
concentration respectively (GopalDebnathet al.,
2016). The results of present study showed partial
stimulatory effects in comparison with studies
conducted on Clerodendruminfortunatumin Tripura
region. Similar supporting results were observed
with ethanolic leaf extract of Solanumnigrum
(Girija,2015) on seed germination, radical length
and protein content of Trigonellafoenum-graceum.
Higher concentrations showed inhibitory effect
whereas lower concentrations had no effect.
Vignaradiataindicated both stimulatory
and inhibitory response effect to some extent to
leachate concentration of Cosmos and Xanthium
respectively. Reduction in net yield of fallow-
mungbean was reported due to allelochemicals
released by Sunower (Vishwajit, 2017). Sunower
showed signicant allelopathic effect on receptor
plant Mungbean in sunflower-mungbean crop
rotation. Cosmos and Xanthium though are not
cultivated plants but show inhibitory effects due
to release of various allelochemicals. The root
length of Mungbean was inhibited at 91.91% and
seedling growth as inhibited at 52.05% at 50mg/
ml concentration of leaf extracts of Diospyros kaki
(Cui, 2017) similar to results of effects of Cosmos
and Xanthium leaf leachates.
Correlation graph and standard deviation
calculations and observations resulted in signicant
inhibition of hypocotyls and coleoptiles growth of
all three selected crops with difference in variation
to response to the allelochemials. Stimulatory effect
could be observed at 1% and 2% concentration
at par with control. Inhibition concentration was
observed at 6% concentration of leaf leachates of
Xanthium and Cosmos.
Increased concentrations of allelo
chemicals suppress the mitotic activity of young
cells or embryo resulting in inhibition of seed
germination. Bioassay conditions play a major
direct role in seed germination such as light
conditions and humidity (Chen Fenget al. 2017,
NEERI REPORT, 2000). There was direct effect
of temperature on emergence of hypocotyl and
coleoptile throughout the experiment.
Phytochemical analysis
Phytochemicals revealed that alkaloids,
saponins, phenols, tannin, avonoids and proteins
are present in the extract.
RESULTS
Phytochemical analysis conducted on the
plant extracts revealed the presence of constituents
which may probably show medicinal bioactivities.
Analysis of the plant extracts of Cosmos revealed
the presence of phytochemicals such as phenols,
phytosterols, tannins, avonoids and alkaloids
with absence of saponins, carbohydrates and
proteins. Whereas phytochemical analysis results
for Xanthium plant extract revealed the presence
of alkaloids, tannins and avonoids but absence of
saponins and phenols.
DISCUSSION
Biologically active molecules present
in plants are phytochemicals. Phytochemical
analysis is considered as major analytical part for
detection of various compounds.These compounds
are useful to understand the ecology and stress
conditions of plants.Phytochemical analysis
conducted on Xanthium strumarium (FarooqUmer,
2014) revealed the presence of similar secondary
metabolites such as alkaloids, phenols, avonoids
tanninsand terpenoids but with variations in
saponins, glycosides, steroids.
Phytochemical screening tests on Cosmos
sulphureus plant extract (Jadav, 2017) revealed the
presence of proteins, avonoids, phenols, alkaloids,
831 GHAYAL et al., Biosci., Biotech. Res. Asia, Vol. 15(4), 821-832 (2018)
tannins, saponins which are similar to the results
obtained from tests conducted on Cosmos from
Pune region. Similarities and differences in results
suggest different responses to environmental stress
conditions from two different geographical areas.
GC – MS results
The allelopathic potential exhibited by
both the weeds might be due to different types of
allelochemicals existing in them. The dominance
of these two weeds and their inhibitory activity on
the other plants and also the crops can be attributed
to the presence of different types of ecochemicals
existing in them which are detected with GC-MS.
GC-MS analysis of ethyl acetate extract of both
samples revealed the presence of some similar
compounds. The major constituents were esters,
ethers, anhydride and polyalcohols.
IR spectroscopy results
FTIR analysis of Cosmos and Xanthium in
the range 4000-400 cm-1 showed the characteristic
ngerprinting regions of various functional groups
such as –OH, carbonyl, anhydride, ester, amide.
For example 3517 cm-1for free –OH group, 2323
cm-1and 2917cm-1for –C-H stretching. FTIR
data suggested the probability of presence of
compounds containing these functional groups.
GC-MS analysis of both samples ethyl acetate
plant extract, revealed the presence of similar
compounds. The major constituents were esters,
ethers, anhydride and polyalcohols. (Tables 9 and
10)
DISCUSSION
Isolation, detection and identification
of functional groups is important part of
allelopathic studies that helps to recognize
nature of allelochemicals released by plant in
response to uctuating environmental conditions.
These chemicals are from different groups as
phenolic acids such as ferulic, p-coumaric acids,
p-hydroxy benzoic acids, cyanogenic glycosides,
tannins etc. Studies reveal that allelopathy is
result of compounds having different actions as
antagonistic, synergistic on plants in the vicinity.
Ghayalet al. (2007) and RuBaiet al. (2009) have
carried out similar studies on phytotoxic effects of
invasive weeds and their GC-MS analysis.
CONCLUSION
Though we are trying for increasing the
sustainable organic agriculture, the over dominating
herbaceous invasive species near agricultural land
are posing great problems. This occurs through
allelobiogenesis whose mechanism needs to be
clearly understood for overcoming such problems.
In the experiments conducted it was mainly
observed that Xanthium had signicant effect on
crops than Cosmos. The effects are directly related
to expanse or density of weed and age of plant. In
spite of both the invasive species being members
of Asteraceae, the impact was different, which
may be probably due to the different combinations
of allelochemicals. Hence to know the nature of
allelochemicals, rst the qualitative analysis was
carried out which revealed the presence of phenols,
phytosterols, tannins, avonoids and alkaloids in
both the aliens. Further GC-MS analyses helped
to characterize the ecochemicals which might be
having allelopathic activity. Detail quantication
and observation of individual chemical effect could
be further line of research.
ACKNOWLEDGEMENTS
The authors are thankful to Principal,
MES Abasaheb Garware College and heads,
departments of Biodiversity, Botany and Chemistry
for their constant support in carrying out this
research and providing the facilities.
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... Similarly, phenolic acids isolated from Ambrosia trifida L. significantly inhibited the germination and growth of wheat and maize crops (42) as they did with lettuce and tomato in our study. Allelopathic effects of invasive weeds (4,15,17,23,32,42) were found more pronounced, which is consistent with results in our study, where the three tested invasive weeds (Abutilon theophrasti, Ambrosia artemisiifolia and Xanthium strumarium) were used as donor plants. Vidotto et al. (40) found that tomato was the most sensitive indicator crop species to common ragweed allelochemicals, as its growth was reduced by > 50 % in both laboratory and greenhouse experiments and the effects were higher than other tested species (alfalfa, barley, maize, lettuce and wheat). ...
... Shoot extracts had stronger inhibitory impact on tested crops, while maize was the most sensitive plant, followed by rye, wheat and oat. Young seedlings in the genus Xanthium release toxic allelochemicals, which proves fatal to neighboring plants (15), reducing germination, seedling growth and chlorophyll content in lentils due to the allelopathic activity of common cocklebur aqueous extract (4). Consistently, our results confirmed a significant impact of leaf and stem aqueous extracts of common cocklebur on the germination and early growth of tomatoes. ...
... The method was modified and adapted following the procedure reported by Miteluț and Popa (2011) and Ghayal et al. (2018). The aim of the study was to evaluate the phytotoxic potential of extracts obtained from fenugreek seeds in ethanol 40%, 70% and propylene glycol 50%. ...
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Chapter
In this essay, we have provided a brief review of the rapidly expanding literature on biological invasions. Many of the hypotheses explored above are not mutually exclusive, and the processes that underlie them may act simultaneously, in concert or in opposition, to determine the ultimate success or failure of an invader at each invasion stage. Though we have tried to be thorough, experienced researchers in the field will no doubt formulate additional hypotheses that warrant investigation. To date, most experiments have focused on only a single hypothesis for a small subset of invasive species under particular environmental conditions. To arrive at a realistic understanding of the ecological processes underlying biological invasions, a more integrative approach is warranted — one that examines the relative importance of each processes for a variety of species under myriad environmental conditions. This will prove to be a daunting task indeed, but one that will perpetuate the expansion of the field of invasion ecology for years to come, thereby ensuring plenty of fruitful lines of research for the keen investigators of the future.