Mitigation of wheat seedlings to the allelopathic effect of Malva parviflora and Rumex dentatus weeds

A laboratory bioassay was conducted to assess the response of wheat seedlings to the produced allelochemicals of the most invasive weeds in the Nile Delta in Egypt, Rumex dentatus and Malva parviflora. Wheat grains germination percentages, seedlings growth criterion and offsetting secondary metabolites were studied. Results indicated that R. dentatus and M. parviflora produced allelochemicals (phenolic acids, alkaloids and saponins) which variably impede wheat grains germination and seriously inhibit growth of wheat seedling. R. dentatus and M. parviflora inhibition was a function of their extract concentration and the growth stage of extracted weed. Root extracts of the two weeds especially at the highest concentration exhibited the greatest inhibitory effects. Contradictory shoot extracts of the two weeds at the fruiting stage led to more inhibition in germination percentages than root extracts. Seedlings weight of germinated wheat variably repressed by the extracts of the two weeds, the highest extract concentration caused the noticeable effect. The growth in seedling length was on the opposite progressively increased by the used extracts. This was confirmed by the counteracting allelochemicals produced in seedlings. Saponin and phenolic compounds represented the most allelochemicals produced by wheat seedlings as a defensive response to the two weeds. Wheat seedling metabolizes more saponin or phenolics to counteract the inhibition of any of the two types of compounds.