Allelopathic effects of Euphorbia thyrsoidea and Oxalis latifolia on germination and seedling growth of Triticum aestivum

Allelopathy involves the release of bioactive compounds from plants that influence the germination and growth of surrounding species. Limited evidence exists on the allelopathic effects of common weeds on wheat germination. This study aimed to evaluate the allelopathic potential of Euphorbia thyrsoidea Boiss. and Oxalis latifolia Kunth. on Triticum aestivum L., focusing on their effects on seed germination and early seedling growth parameters. The experiment was conducted using a completely randomized design (CRD) with three replicates. Fresh shoots and roots of both weeds were soaked in distilled water to prepare aqueous extracts at concentrations of 5%, 10%, and 15% (w/v), and the dry plant material was mixed with sterile sand for mulching. Extracts were applied to wheat seeds in sterilized Petri dishes, with distilled water as the control. Data on plumule length, radicle length, root number, leaf area, and germination percentage were recorded after 72 h of incubation at 25°C. Descriptive statistics and comparative analysis were used to assess differences between treatments. Aqueous extracts of fresh shoots significantly reduced plumule and radicle length, root number, and germination percentage compared to the control. However, shoot extracts increased radicle length to 6.2 cm (control: 5.3 cm) and plumule length to 9.0 cm (control: 6.6 cm) in the combined treatment. Fresh root extracts reduced all germination parameters, although 5 g of root extract enhanced radicle length to 7.6 cm and the combined root extract to 7.3 cm (control: 6.9 cm). Mulching treatments with both weeds reduced growth parameters, but the mixed mulch increased leaf area to 2.1 cm² (control: 1.5 cm²) and did not affect germination. The findings demonstrate that E. thyrsoidea and O. latifolia release allelochemicals capable of suppressing germination and early growth of T. aestivum, while some extract combinations may stimulate specific growth parameters. These weeds exhibit strong allelopathic potential and should be further investigated for possible insecticidal and herbicidal applications. Future studies should identify the active compounds involved and evaluate their field-level implications.