Investigation on growth stages and germination of Cynanchum acutum in pistachio orchards in border of Iran Central Desert (Esfehan province, Iran)

In this research، the seed viability and growing status of Swallow-wort (Cynanchum acutum Willd.)، as an alien weed، which has been invasive in pistachio orchards of Aran and Bidgol، north of Esfehan province، was studied. The viability of seeds of this plant which were collected from previous year was tested using tetrazolium solution. The periods of growth stages of the weed in pistachio orchards from seedling emergence up to seed repining were recorded. Further more، seed and rhizome germination of this plant from soil depth was studied. Results indicated that 80-96 percent of the seeds collected from previous year were alive. In nature، emerging the first rhizome-originated seedlings were observed in initiation of March، maximized in mid March and stopped in the first days of June. Emerging of the seed-originated seedlings started from mid April، maximized in initiation of May and stopped at the end of this month. Most rhizome- and seed-originated seedlings were grown respectively in 10-19 and 1-9 cm soil depths. The plants originated from seeds didn''t attach to the pistachio trees.