Soybean is a high-value food source, and the invasive weeds Mexican prickly poppy (Argemone ochroleuca) could release allelochemicals that inhibit the growth of this crop. The impact of A. ochroleuca on the germination and growth of soybean is not well documented. Therefore, the aim of this study was to evaluate the TLC profiles of different extracts of A. ochroleuca and assess the effects of extracts on the germination of soybean seeds. Shoots and roots of A. ochroleuca were weighed and 100 g of each was separately extracted with 1000 mL deionized water, hexane or acetone. Ten concentrations of water extracts ranging from 10 to 100 mL per 100 mL of deionized water and three concentrations of acetone and hexane extracts ranging from 2.5 to 7.5 g/L were separately used for seed germination bioassays. Thin-layer chromatography (TLC) analysis was used to compare the chemical profiles in the shoot and root water, and in the hexane and acetone extracts of A. ochroleuca. The highest reduction was recorded from the water extract, at 100%. The TLC profiling of A. ochroleuca addressed different classes of compounds, including alkaloids, phenolic acids and flavanoids. There is, however, a need to identify the most active phytochemicals in the suppression of germination.

Meloidogyne incognita, a widespread and damaging plant parasite, reduces crop yields. Chemical treatments are common but pose health and environmental risks, leading to a search for safer alternatives. Plant extracts with secondary metabolites, like those from Maerua angolensis and Tabernaemontana elegans, show promise for nematode control, though their efficacies vary. This study aimed to investigate how the timing of applying T. elegans and M. angolensis extracts influenced the population densities of M. incognita and the growth of tomato (Solanum lycopersicon L.) plants. The experiment was a factorial design with two plant extracts applied at 5 g per plant and three different timings of application relative to nematode inoculation. Additionally, the experiment included positive (chemical standard (Nemacur^® 10 GR)) and negative (plants inoculated with nematodes only) controls, alongside naturally grown plants. The results indicate that applying plant extracts before the nematode inoculation or simultaneously with the inoculation reduced the total nematode populations as effectively as the Nemacur positive control. Plants treated with extracts showed improved growth variables compared with those treated with Nemacur^® and the natural growing conditions. In conclusion, applying plant extracts before or simultaneously with nematode inoculation effectively suppressed the nematodes and enhanced the plant growth variables. These findings suggest that such plant extracts could be adopted as part of integrated nematode management strategies in agricultural settings.

Argemone ochroleuca Sweet is an alien invasive weed dominating most cultivated lands, however, the phytochemicals present in this plant and the effects of these on the germination and growth of economically important crops such as maize are not well-documented. The objective of the study was to characterize the phytochemistry of the shoots and roots of A. ochroleuca and determine whether the extracts could inhibit the germination of maize seeds. The shoots and roots of A. ochroleuca were extracted in water, hexane, and acetone. Ten maize seeds were used in the germination bioassay. A phytochemical analysis was conducted using gas chromatography-mass spectrometry (GC-MS). The effects of the A. ochroleuca water, hexane, or acetone extracts on maize seed germination were concentration and plant-part dependent. The highest reduction was recorded from the water extract with 82%. Identified compounds with high percentages in A. ochroleuca were 9,12-octadecadienoic acid (Z,Z) and 9,12,15-octadecatrienoic acid, (Z,Z,Z)-. The present study indicated that A. ochroleuca extracts suppress the germination of maize seeds, likely due to the presence of both the identified and potentially unidentified phytochemicals that were not detected by the selected method. There is, however, a need to establish the relationship between the phytochemical compounds and the enzymes responsible for germination.