Effect of extract of different organs of Marigold (Tagetes erecta) medicinal plant on germination and growth characteristics of some weeds

In order to investigate the effect of allelopathy of different organs of Mexican marigold on germination and growth of weeds and crops, a factorial experiment was conducted in a completely randomized design with three replications in greenhouse conditions. The first factor consisted of 5 concentrations of marigold extract (0, 5, 10, 25, 50 and 100% of) and the second factor included three different parts of marigold organs (leaves, stems and roots). Different extracts of different organs of marigold were applied on weeds of amaranthus, white goosefoot, phalaris, ryegrass, wiled barley and corn. The results showed that with increasing the extract, germination percentage, germination coefficient, germination rate, root length, shoot length, fresh and dry weight of seedlings decreased and the lowest measurement traits were obtained at 100% concentration of the extract. Concentration of 50% of extracts of different organs of marigold (leaves, stems and roots) resulted in non-germination of weed seeds of amaranthus, phalaris and white goosefoot. Germination of ryegrass and maize was stopped at 100% of the extract. Root extract had a greater inhibitory effect on weeds of amaranthus and white goosefoot. While the inhibitory effect of stem extract on phalaris weed and corn was greater. In general, the results showed that among the studied weeds, phalaris germination was more sensitive than other weeds and more sensitive to other weeds, as at lower concentrations of the extract, germination percentage was stopped. Among the extracts of marigold, the root extract had the greatest effect on inhibiting weeds and corn. Marigold plant extract had more inhibitory effect on the roots of weeds and corn and the stems of these plants were less affected. Weeds with smaller seeds also became more sensitive to lower concentrations and their germination stopped.