Concentrations of the active organic compounds estimated in
Plantago major L. (Plantaginaceae family) has been used as herbal remedies for centuries in almost all over the world and in the treatment of a number of diseases. This study aims to assess the allelopathic potential of Plantago major extracts on the germination and early seedling growth of purslane. Total phenols, tannins, saponins, flavonoids, and alkaloids were determined in P. major. Furthermore, concentrations of 2.5, 5, 10, 20, and 40 mg.ml−1 of both alcoholic and aqueous extracts were prepared to study their phytotoxic effect on the germination and seedling growth of Portulaca oleracea weed. In our study, showing the germination of P. oleracea was completely inhibited (96.30 mg.ml−1) under treatment of P. major methanolic extracts at 40 mg ml−1. Moreover, both radicle and plumule were strongly inhibited (87.20 and 74.29 mg.ml−1, respectively) under the same treatment. This could be attributed to the high content of bioactive constituents. Therefore, this species can be used in the method of biological control of weeds. In addition, further studies are required to identify and characterize the proper allelochemicals and demonstrate their modes of action.
- Plantago major
- Portulaca oleracea
At present there is a lot of emphasis on finding new methods to fight weeds, and concept of competition between plant species has been improved with that of plant allelopathy [1, 2]. Allelopathy involves the effects of one plant on another because of the chemicals it releases or the breakdown products of their metabolites . There are some examples of plant toxins among the plant secondary compound classes of alkaloids, terpenes, and especially phenolics . Phytotoxicity assays have been reported to be an important approach for identifying plants that are likely to be a source of vital herbivorous compounds [5, 6].
The allelopathic effects of crop plants or crop residues on weeds benefit farmers, which can cause significant economic losses . There is competition for weed crops for moisture, nutrients, space, and light, which negatively affects crop yield . It has been reported that the predominant species of weed allelochemicals stop crop production but sometimes also stimulate seed growth, germination, and crop production [9, 10].
Management methods that reduce the requirement for herbicides are needed to reduce adverse environmental impacts. Herbicides can cause crop injury . Moreover, there is a keen interest in developing alternative methods of natural weed control in organically grown crops , as weed control remains one of the most significant agronomic challenges in the production of organic crops. Weed management is often the most troublesome technical problem to be solved in organic farming, especially in poorly competitive crops like vegetables [6, 13]. Cultivation and hand hoeing are common practices used in organically grown leek crops.
Phytochemical investigation of the genus revealed the presence of polysaccharides, phenylpropanoid glycosides, alkaloids, triterpenes, flavonoids, and phenolic acids as the main bioactive compounds present in the aerial parts [17, 18, 19, 20]. The aim of the present study was to evaluate the allelopathic potential of
2. Materials and methods
2.1 Plant material
2.2 Phytochemical analysis
2.3 Allelopathy bioassay weed seed source
The seeds of
2.4 Preparation of extracts
For bioassay tests, aqueous and methanol extracts were prepared to obtain various concentrations of 2.5, 5, 10, 20, and 40 mg.ml−1 (w/v). The solutions were filtered through double layers of muslin cloth followed by Whatman No. 1 filter paper. The pH of the mixtures was adjusted to 7 with 1 M HCl, and then mixtures were stored in a refrigerator at 4°C until further use .
2.5 Germination bioassay
For germination experiment, 25 seeds were placed in each filter paper in addition to 10 ml of tested extract for each Petri dish (90 mm diameter). The control treatment was designed with distilled water. Germinated seeds were counted daily starting from the first day of treatment. The design of the experiment was randomized complete block with three replicates. The experiment was repeated three times, and the inhibition percentage was calculated.
2.6 Seedling growth bioassay
The seeds of
3. Results and discussion
3.1 Phytochemical constituents
Several phytotoxic substances causing germination and/or growth inhibitions have been isolated from plant tissues [30, 31]. The phytochemical constituents of
|Plant species||Active organic compounds (mg.g−1 dry weight)|
|132.2 ± 2.35||28.7 ± 0.89||10.6 ± 0.05||14.8 ± 0.21||15.8 ± 0.06|
These results are supported with the study of Kolak et al.  and Miser-Salihoglu et al. . In addition, this results relatively comparable to those reported in
3.2 Allelopathic effect of
P. majorextracts on P. oleraceagermination
Allelopathy is a phenomenon by which some plants affect the others, either positively or negatively, by exuding chemicals . In the present study, the allelopathic effect of shoot extracts (aqueous and methanol) on the germination percentage of
Many plant species showed inhibitory effects on
3.3 Allelopathic effect of
P. majorextracts on P. oleraceaseedling growth
Allelopathy offers potential for biorational weed control through the production and release of allelochemics from leaves, flowers, seeds, stems, and roots of living or decomposing plant materials. Under appropriate conditions, allelochemics often exhibit selectivity, similar to synthetic herbicides .
The allelopathic effect of both aqueous and methanolic extracts on
The phytotoxic effect of both methanolic and aqueous extracts from the studied
The allelopathic effect of
In conclusion, the aim of this study was to assess the allelopathic potential of