the allelopatic effects of aqueous extracts and decay durations of sunflower on germination and growth of dodder (cuscuta compestris yuncker)

in order to evaluate the allelopathic potential of sunflower (helianthus annus l.) organs on germination and growth of dodder (cuscuta compestris l.), series studies were conducted in three separate experiments; as factorial based on completely randomized design (crd) with three replications for each experiments. first experiment was conducted in petri dishes and consisted of sunflower organs at four levels (root, stem, leaf and total plant without inflorescence) and their aqueous extract concentrations at 11 levels (0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10%). second experiment was conducted in pots and factors were include of sunflower organs at four levels (root, stem, leaf and total plant without inflorescence) and their aqueous extract concentrations at five levels (0, 2.5, 5, 7.5 and 10%). third experiment was sunflower organs at four levels (root, stem, leaf and total plant without inflorescence) and decay durations at 8 levels (0, 15, 30, 45, 60, 75 and 90 days decay and control). in three experiments, dry weight and length of seedling, number of abnormal seedlings, percentage and rate of dodder germination were examined. results of three experiments showed that leaf and stem in comparison with other sunflower organs had more allelopatic effects on mentioned traits of dodder. in addition, sunflower organs had more allelopatic effects on percentage and rate of germination and percentage and rate of emergence in compared with other studied traits.