rate; (4) changing the activity of many enzymes like phosphorylase, peroxidase,
catalase and ATPase; (5) reducing or inactivating the activity of plant hormones; and
(6) inhibiting protein synthesis and reducing DNA and RNA integrity [61].
Low-molecular-weight organic compounds such as phenolic acids are present in
root exudates and decomposition residues, among them acids trans-cinnamic acid,
vanillic, p-coumaric, ferulic, and salicylic acids have been reported, as summarized
by Tian, Bi, Sun, Zhang [75]. Using as a background the knowledge that the effects
of allelochemicals are dose-dependents [76], it is known that in low concentrations
they can boost plant growth and in high concentrations they inhibit, promote, or have
no effect on plant growth [77]. Tian, Bi, Sun, and Zhang [75] studied the allelopathic
effects of phenolic acids on Colletotrichum gloeosporioides, a species of fungus
responsible for damage to strawberry crops. The authors detected the presence of
ten phenolic acids in soils: gallic acid, protocatechuic acid, chlorogenic acid,
p-hydroxybenzoic acid, caffeic acid, syringic acid, vanillin, p-coumaric acid, ferulic
acid, and trans-cinnamic acid and observed that in the lowest concentration tested,
the germination and growth could increase whereas in higher concentrations, they
could reduce the disease in strawberry crops, demonstrating the potential beneficial
allelophatic use.
In order to study the chemical composition and the allelophatic potential of Nigella
sativa, Zribi, Omezzine, and Haouala [78] used aerial parts and seeds aqueous extracts
from different developmental stages (vegetative, flowering, and fruiting). According to
the authors, the phytochemical composition formed by phenolics, flavonoids, flavonols, flavones, and alkaloids were high in the vegetative stage and they contributed
significantly to the allelophatic activity of the species; some of them are also present in
the P. juliflora chemical composition [78]. The aqueous extracts delayed germination
and seedling growth depending on the stage of development, showing that this is an
important parameter related to allelochemical compounds [78, 79].
Specifically related to P. juliflora, Kaur, Callaway, and Inderjit [74] evaluated the
production, accumulation, and inhibitory effects of phenolic in soils found under
P. juliflora compared to the seed growth of Brassica campestris. The authors found
out that the soils beneath P. juliflora present higher levels of total phenolics than the
soil from open areas and suppression in Brassica campestris growth. These results
were similar to those presented by Kaur, Gonzáles, Llambi, Soriano, Callaway, Rout,
Gallaher, and Inderjit [80], where the soil beneath the P. juliflora canopy showed
higher levels of total phenolics and those one published by Inderjit, Seastedt,
Callaway, Pollock, and Kaur [45], which presented a phenolic-rich soil under
P. juliflora causing suppression in Bambusa arundinacea growth.
Recently, a study evaluated phytotoxicity of P. juliflora and its potential on weed
control and yield of wheat through a two-year experimental design. The author used
P. juliflora extracts from leaves, bark, and root and used as parameters the following:
weed density, fresh weed biomass, dry weed biomass, chlorophyll content, leaf area
index, leaf area duration, crop growth rate, net assimilation rate, plant height, and
number of tillers. After application of the extracts, all parameters were significantly
reduced, showing that the phytotoxic compounds of P. juliflora can also cause
negative effects on agricultural crops [81].
22 Prosopis juliflora: Phytochemical, Toxicological, and Allelochemicals
531
catalase and ATPase; (5) reducing or inactivating the activity of plant hormones; and
(6) inhibiting protein synthesis and reducing DNA and RNA integrity [61].
Low-molecular-weight organic compounds such as phenolic acids are present in
root exudates and decomposition residues, among them acids trans-cinnamic acid,
vanillic, p-coumaric, ferulic, and salicylic acids have been reported, as summarized
by Tian, Bi, Sun, Zhang [75]. Using as a background the knowledge that the effects
of allelochemicals are dose-dependents [76], it is known that in low concentrations
they can boost plant growth and in high concentrations they inhibit, promote, or have
no effect on plant growth [77]. Tian, Bi, Sun, and Zhang [75] studied the allelopathic
effects of phenolic acids on Colletotrichum gloeosporioides, a species of fungus
responsible for damage to strawberry crops. The authors detected the presence of
ten phenolic acids in soils: gallic acid, protocatechuic acid, chlorogenic acid,
p-hydroxybenzoic acid, caffeic acid, syringic acid, vanillin, p-coumaric acid, ferulic
acid, and trans-cinnamic acid and observed that in the lowest concentration tested,
the germination and growth could increase whereas in higher concentrations, they
could reduce the disease in strawberry crops, demonstrating the potential beneficial
allelophatic use.
In order to study the chemical composition and the allelophatic potential of Nigella
sativa, Zribi, Omezzine, and Haouala [78] used aerial parts and seeds aqueous extracts
from different developmental stages (vegetative, flowering, and fruiting). According to
the authors, the phytochemical composition formed by phenolics, flavonoids, flavonols, flavones, and alkaloids were high in the vegetative stage and they contributed
significantly to the allelophatic activity of the species; some of them are also present in
the P. juliflora chemical composition [78]. The aqueous extracts delayed germination
and seedling growth depending on the stage of development, showing that this is an
important parameter related to allelochemical compounds [78, 79].
Specifically related to P. juliflora, Kaur, Callaway, and Inderjit [74] evaluated the
production, accumulation, and inhibitory effects of phenolic in soils found under
P. juliflora compared to the seed growth of Brassica campestris. The authors found
out that the soils beneath P. juliflora present higher levels of total phenolics than the
soil from open areas and suppression in Brassica campestris growth. These results
were similar to those presented by Kaur, Gonzáles, Llambi, Soriano, Callaway, Rout,
Gallaher, and Inderjit [80], where the soil beneath the P. juliflora canopy showed
higher levels of total phenolics and those one published by Inderjit, Seastedt,
Callaway, Pollock, and Kaur [45], which presented a phenolic-rich soil under
P. juliflora causing suppression in Bambusa arundinacea growth.
Recently, a study evaluated phytotoxicity of P. juliflora and its potential on weed
control and yield of wheat through a two-year experimental design. The author used
P. juliflora extracts from leaves, bark, and root and used as parameters the following:
weed density, fresh weed biomass, dry weed biomass, chlorophyll content, leaf area
index, leaf area duration, crop growth rate, net assimilation rate, plant height, and
number of tillers. After application of the extracts, all parameters were significantly
reduced, showing that the phytotoxic compounds of P. juliflora can also cause
negative effects on agricultural crops [81].
22 Prosopis juliflora: Phytochemical, Toxicological, and Allelochemicals
531