Allelopathic Potentiality of Euphorbia hypericifolia L. on Germination and Seedling Development of Sympatric Crops and Weeds

Abstract

Euphorbia hypericifolia, a non-native herbaceous weedy plant was found to often form disproportionately dense, virtually monospecific stands in the Mount Bambouto Caldera, Cameroon. This observation is within the purview of allelopathy and is attributed to the release of botanicals by non native plants that harm naïve native flora, creating significant problems for agriculture and the environment. We investigated if the invasiveness of E. hypericifolia could be explained by its allelopathic potential at varying concentrations on five indicator plants. The results showed that the leaf, root and stem aqueous extracts of the plant exhibited significant inhibitory effects on the germination, radicle and plumule lengths of Biden pilosa, Amaranthus spinosus, Lactuca sativa, Zea mays and Lycopersicon esculentum at 100 % by 75.0, 69.4, 95.6, 28.0 and 97.2 %, respectively. The leaf extract was the most potent, while the stem extract was the least. The extract of E. hypericifolia was stimulatory (Lower concentrations) and inhibitory to the germination and growth of the test plants and its effect was concentration-dependent with the roots of target plants being more sensitive to the extracts than the plumule. L. esculentum was the most susceptible species to E. hypericifolia extracts while Z. mays was more tolerant than any of the tested plants. Results of total chlorophyll pigment accretion showed declining levels of chlorophyll detected in the leaves of tomato transplants cultivated in the augmented soils with rising dosage of the leaf residue of E. hypericifolia. B. pilosa planted on E. hypericifolia infested soil (EIS) showed very poor emergence recording only 7.5 % after 6 weeks as compared to 83.0 % in non E. hypericifolia infested soil (NIS). Qualitative phytochemical screening indicates E. hypericifolia is rich in secondary metabolites including alkaloids, glycosides, flavonoids, phenolics, tanins, Steriods and saponins. Acetone was the best extractant amongst the solvents used. This study has proven the allelopathic potential of E. hypericifolia and revealed some allelochemicals that may be exploited for the development of bioherbicides and plant growth promotion from natural products.

Chemotaxonomy Significant in Delimitation of Six Taxa of Euphorbia L. in Iraq

“…Flavonoids and phenols have been noticed in E. serpens only, while terpenes and tannins found in E. prostata and E. hirta respectively. The results also were compatible with previously reported by [20], about the phtytocomponents of E. hirta, however, the researchers [6], identified flavonoids as mostly contain phytochemical constituents in Euphorbia serpens, alkaloids and saponins were identified by [21], in Euphorbia hypercifolia. The most effect biochemical compounds alkaloids, flavonoids, terpenes and saponins are found in nonpolar solvent hexane (Table .7).…”

“…Nevertheless, different types of terpenes have been isolated from E. milii var. milii [19][20][21]. The chromatogram of the GC-MS analysis of six taxa of Euphorbia illustrated the peaks of the chemical compounds, molecular weight, molecular formula, area as well as their retention time were reported in Figure 1-6…”

Weeds as Reservoirs of Beneficial Insects to Control Pests in Crops

“…Euphorbia hypericifolia L. (Euphorbiaceae) a cosmopolitan-native plant, had allelopathic effects on germination of other weeds such as B. pilosa at 100% and crops such as maize at 28% (Ndam et al 2021) and was used for biological control against larvae of Gadirtha fusca Pogue (Lepidoptera: Nolidae) (Wheeler et al 2018). Malva parviflora L., (Malvaceae) cosmopolitan-exotic, is a host of whitefly, Bemisia tabaci (Gennadius) (Muñiz 2000); Rosa gallica L. (Rosaceae) (cosmopolitan-exotic) is an economically important plant for aromatic oil for cosmetics, positive effects on health (Todorova et al 2020), and indicator of drought and soil fertility (Monder 2018).…”