main allelochemicals present in aqueous extract of Amaranthus retroflexus analyzed
by gas chromatography-mass spectrometry (GC-MS).
According to a research report, extract and exudates of Microcystis aeruginosa
showed allelopathic effect on different processes of Vallisneria natans like
physiological response, microbial stress of biofilm on leaves, and photosynthetic
activity [66]. Results proved that allelochemical can cause physiological stress
on the leaf biofilm and also affect surface topography of Vallisneria natans leaves.
Microbial community in biofilm was more affected by exudate than extract.
Evaluation of allelopathic potential and phytochemical analysis of five Amaranthus
species: (a) A. viridis, (b) A. hybridus, (c) A. deflexus, (d) A. retroflexus, and (e) A.
spinosum. Ethanolic leaf extract was prepared and tested against Lactuca sativa [67].
Phytochemical analysis showed the presence of steroids, carotenoids, and organic
acids in all species. Extract concentrations that were used for testing showed an
inhibitory effect on germination and the germination speed index of Lactuca sativa
seeds in a dose-dependent manner.
Melaleuca cajuputi extract was prepared by using Soxhlet assembly and extraction of supercritical carbon dioxide and characterized by GC-MS and reported two
major sesquiterpenes: caryophyllene and humulene [68]. The extract was tested
against notorious paddy weeds which are known as barnyard grass to check its
allelopathic effect. Melaleuca cajuputi extract proved allelopathic effect against
weed. Also, Melaleuca cajuputi oil can be used as bioherbicides.
Leaf extract (aqueous) and leaf litter (aqueous) of Melia dubia Cav. were studied
for its allelopathic potential against early growth, germination, and biomass of the
Solanum melongena L. and Capsicum frutescens L. by pot culture bioassay in
laboratory. GC-MS was used to analyze Melia dubia leaf litter which showed the
presence of derivatives of phenolic acids and unsaturated fatty acids, omega-3 fatty
acid, chromene, aromatic ketone, alkaloids, and methyl ketones. Both extracts
inhibited the germination traits, but in early stage allelopathic effect was seen and
it disappeared in later stage [69].
A study was conducted to check the extract of Chaetoceros curvisetus on the
growth of Skeletonema costatum, and it showed allelopathic activity. The isolation
and characterization of allelochemicals responsible for activity were performed
using chromatography and HPLC-electrospray time-of-flight mass spectrometry
(ESI-TOF-MS). 2-(2-Cyanophenyl) amino)-2-oxoethyl,3-cyclohexyl propanoate
was an allelochemical present in Chaetoceros curvisetus [70].
Parthenium hysterophorus is also reported to have allelopathic effect [71, 72 ].
Leaf aqueous extract of Parthenium hysterophorus inhibits the germination and
growth of barley, peas, corn, and wheat [73]. In a research investigation,
the extract was prepared by using enhanced solvent extraction/supercritical CO 2 ,
and allelopathic compounds were isolated from sunflower leaves by using highpressure techniques [74]. Various types of compounds were isolated by this method
including flavonoids, terpenes, heliannuols, and fatty acids from Helianthus annuus
leaves. Most effective inhibiting effect is shown by tambulin, sesquiterpene 10-oxoisodauc-3-en-15-al, heliannuol D, and pinoresinol. Effects of Artemisia ordosica
leaves extract (aqueous) were tested against Nostoc sp. and Chlorella vulgaris [75].
19 Plant Allelochemicals and Their Various Applications
451
by gas chromatography-mass spectrometry (GC-MS).
According to a research report, extract and exudates of Microcystis aeruginosa
showed allelopathic effect on different processes of Vallisneria natans like
physiological response, microbial stress of biofilm on leaves, and photosynthetic
activity [66]. Results proved that allelochemical can cause physiological stress
on the leaf biofilm and also affect surface topography of Vallisneria natans leaves.
Microbial community in biofilm was more affected by exudate than extract.
Evaluation of allelopathic potential and phytochemical analysis of five Amaranthus
species: (a) A. viridis, (b) A. hybridus, (c) A. deflexus, (d) A. retroflexus, and (e) A.
spinosum. Ethanolic leaf extract was prepared and tested against Lactuca sativa [67].
Phytochemical analysis showed the presence of steroids, carotenoids, and organic
acids in all species. Extract concentrations that were used for testing showed an
inhibitory effect on germination and the germination speed index of Lactuca sativa
seeds in a dose-dependent manner.
Melaleuca cajuputi extract was prepared by using Soxhlet assembly and extraction of supercritical carbon dioxide and characterized by GC-MS and reported two
major sesquiterpenes: caryophyllene and humulene [68]. The extract was tested
against notorious paddy weeds which are known as barnyard grass to check its
allelopathic effect. Melaleuca cajuputi extract proved allelopathic effect against
weed. Also, Melaleuca cajuputi oil can be used as bioherbicides.
Leaf extract (aqueous) and leaf litter (aqueous) of Melia dubia Cav. were studied
for its allelopathic potential against early growth, germination, and biomass of the
Solanum melongena L. and Capsicum frutescens L. by pot culture bioassay in
laboratory. GC-MS was used to analyze Melia dubia leaf litter which showed the
presence of derivatives of phenolic acids and unsaturated fatty acids, omega-3 fatty
acid, chromene, aromatic ketone, alkaloids, and methyl ketones. Both extracts
inhibited the germination traits, but in early stage allelopathic effect was seen and
it disappeared in later stage [69].
A study was conducted to check the extract of Chaetoceros curvisetus on the
growth of Skeletonema costatum, and it showed allelopathic activity. The isolation
and characterization of allelochemicals responsible for activity were performed
using chromatography and HPLC-electrospray time-of-flight mass spectrometry
(ESI-TOF-MS). 2-(2-Cyanophenyl) amino)-2-oxoethyl,3-cyclohexyl propanoate
was an allelochemical present in Chaetoceros curvisetus [70].
Parthenium hysterophorus is also reported to have allelopathic effect [71, 72 ].
Leaf aqueous extract of Parthenium hysterophorus inhibits the germination and
growth of barley, peas, corn, and wheat [73]. In a research investigation,
the extract was prepared by using enhanced solvent extraction/supercritical CO 2 ,
and allelopathic compounds were isolated from sunflower leaves by using highpressure techniques [74]. Various types of compounds were isolated by this method
including flavonoids, terpenes, heliannuols, and fatty acids from Helianthus annuus
leaves. Most effective inhibiting effect is shown by tambulin, sesquiterpene 10-oxoisodauc-3-en-15-al, heliannuol D, and pinoresinol. Effects of Artemisia ordosica
leaves extract (aqueous) were tested against Nostoc sp. and Chlorella vulgaris [75].
19 Plant Allelochemicals and Their Various Applications
451