can be used for management of phytopathogens. Plants such as Magnoliaceae,
Amaranthaceae, Brassicaceae, Acanthaceae, and Chenopodiaceae are well known
for their antifungal activities; on the other hand, Papilionaceae, Poaceae, and
Asteraceae are known for their nematocidal activity [116]. Allelopathic effect
of some essential oils of plants Eucalyptus tereticornis, Callistemon lanceolatus,
Artemisia vulgaris, Ageratum conyzoides, Lantana camara, and Ocimum
kelmandescherium on ten phytopathogenic fungi Aspergillus flavus, A. niger, A.
fumigatus, A. terreus, A. parasiticus, Alternaria alternata, Fusarium oxysporum,
Colletotrichum truncatum, Trichoderma viride, and Helminthosporium tericum
was studied [117]. Four essential oils of Callistemon lanceolatus, Eucalyptus
tereticornis, Ageratum conyzoides, and Ocimum kelmandescherium inhibited
the growth of all the fungi tested. One research study reported that bacterial
pathogen can be managed with these secondary metabolites (allelochemicals)
[116]. Another research study reported that intercropping of Chinese chive with
tomato was able to control soil-borne disease (caused by bacteria Pseudomonas
solanacearum) by allelopathic approaches which result in safer and higher-quality
product at lower cost [118]. Crops showing allelopathic effect can be incorporated
into soil (as green manure) to decrease the pathogen population in plants. Crude
extract of these crops can be used as spray against pathogen present in air.
Research study reported that allelochemicals can also show inhibition of the
growth of Microcystis aeruginosa, and it was concluded that these allelochemicals
can significantly control the toxic cyanobacteria [75]. Other research also
supports the plant allelopathic potential in inhibiting the growth of plant
pathogens [119–123].
3.4
Development of Herbicides from Allelochemicals
With the increase use of herbicide, weed became resistant against
these herbicides. So herbicide with new mode of action is needed today [124].
Various allelochemicals with herbicidal activity have been isolated from
different crops [125–127], and allelochemicals with herbicidal activity can be
categorized into two major groups: phenolics and terpenoids [128]. One research
study reported that phenolic compounds showed their allelopathic potential
by inhibiting symbiotic relationship between rhizobium and legume [129].
These natural phytotoxins offer a great opportunity to develop herbicides with
a safe mode of action [130]. Another study investigated that Veronica persica
(Lour.) Merr. had effective herbicidal activity; thus a safer herbicide from
allelochemicals can be developed [131]. Eucalyptus globulus leaf aqueous
extract was tested against the germination potential and early growth of Lactuca
sativa and Agrostis stolonifera. Results showed that this extract has an
inhibitory effect on both target species. Also spraying treatment reduced
both aerial and root biomass and reduced protein contents and chlorophyll
concentrations. HPLC analysis confirmed the presence of eight phenolic
454
A. Bachheti et al.
Amaranthaceae, Brassicaceae, Acanthaceae, and Chenopodiaceae are well known
for their antifungal activities; on the other hand, Papilionaceae, Poaceae, and
Asteraceae are known for their nematocidal activity [116]. Allelopathic effect
of some essential oils of plants Eucalyptus tereticornis, Callistemon lanceolatus,
Artemisia vulgaris, Ageratum conyzoides, Lantana camara, and Ocimum
kelmandescherium on ten phytopathogenic fungi Aspergillus flavus, A. niger, A.
fumigatus, A. terreus, A. parasiticus, Alternaria alternata, Fusarium oxysporum,
Colletotrichum truncatum, Trichoderma viride, and Helminthosporium tericum
was studied [117]. Four essential oils of Callistemon lanceolatus, Eucalyptus
tereticornis, Ageratum conyzoides, and Ocimum kelmandescherium inhibited
the growth of all the fungi tested. One research study reported that bacterial
pathogen can be managed with these secondary metabolites (allelochemicals)
[116]. Another research study reported that intercropping of Chinese chive with
tomato was able to control soil-borne disease (caused by bacteria Pseudomonas
solanacearum) by allelopathic approaches which result in safer and higher-quality
product at lower cost [118]. Crops showing allelopathic effect can be incorporated
into soil (as green manure) to decrease the pathogen population in plants. Crude
extract of these crops can be used as spray against pathogen present in air.
Research study reported that allelochemicals can also show inhibition of the
growth of Microcystis aeruginosa, and it was concluded that these allelochemicals
can significantly control the toxic cyanobacteria [75]. Other research also
supports the plant allelopathic potential in inhibiting the growth of plant
pathogens [119–123].
3.4
Development of Herbicides from Allelochemicals
With the increase use of herbicide, weed became resistant against
these herbicides. So herbicide with new mode of action is needed today [124].
Various allelochemicals with herbicidal activity have been isolated from
different crops [125–127], and allelochemicals with herbicidal activity can be
categorized into two major groups: phenolics and terpenoids [128]. One research
study reported that phenolic compounds showed their allelopathic potential
by inhibiting symbiotic relationship between rhizobium and legume [129].
These natural phytotoxins offer a great opportunity to develop herbicides with
a safe mode of action [130]. Another study investigated that Veronica persica
(Lour.) Merr. had effective herbicidal activity; thus a safer herbicide from
allelochemicals can be developed [131]. Eucalyptus globulus leaf aqueous
extract was tested against the germination potential and early growth of Lactuca
sativa and Agrostis stolonifera. Results showed that this extract has an
inhibitory effect on both target species. Also spraying treatment reduced
both aerial and root biomass and reduced protein contents and chlorophyll
concentrations. HPLC analysis confirmed the presence of eight phenolic
454
A. Bachheti et al.