Study of Allelopathic Effects of Seven Plants on Germination and Initial Growth of Medicinal-industrial Plant Indigo (Indigofera tinctoria)

The allelopathic effect of weeds is one of the important limiting factors that affects the growth and yield of medicinal plants. The allelophatic effects of water extract of purple nutsedge (Cyperas rotundus), creeping jenny (Convonvolus arvensis), bermuda grass (Cynodon dactylon), redroot pigweed (Amaranthus retroflexus), common cocklebur (Xantium strumarium L.), perennial night shade (Solanum nigrum), and sunflower (Helianthus annus) on germination and initial growth of indigo plant (Indigofera tinctoria L.) were investigated. The results showed that, application of extract of all plants decreased percentage rate and uniformity of germination of indigo seeds, also increased the time up to 5, 10, 50, 90 and 95 percent of germination. The lowest percentage of germination (Gmax) was found in bermuda grass and redroot pigweed seeds. The highest seed germination rate was belonging to common cocklebur. The extract of perennial night shade was maximum uniformity effects on germination (GU) of indigo seeds. The highest reduction of radicle and plumule growth was found by use of perennial night shade, creeping jenny, bermuda grass and sunflower extracts. Perennial night shade had the highest effects of reduction of shoot dry weight. Among the all plant extracts, the lowest allelopathic effect on germination, and seedling growth was belonging to common cocklebur.