A perennial species in its native range of Asia and Africa, Benghaldayflower in North America establishes annually from seed. This species hasthe unique ability to produce aerial and subterranean flowers and seeds.Information on how various environmental factors affect Benghal dayfloweraerial and subterranean seed germination and emergence in the United Statesis lacking. Studies were conducted to determine the effect of temperature,planting depth, salt concentration, and pre-emergence herbicides ongermination or emergence of aerial and subterranean Benghal dayflower seed.Maximum aerial seed germination occurred at 30 C, whereas maximumsubterranean seed germination occurred at 30 and 35 C. Germination at 40 Cwas delayed relative to optimum temperatures. The seed coats in this studywere mechanically disrupted to evaluate the response of seeds to temperaturein the absence of physical dormancy. The physical dormancy imposed by theseed coat could require additional study. Benghal dayflower was not tolerantto ≥ 10 mM NaCl, indicating that this exotic species is not likely to becomeproblematic in brackish marshes and wetlands of coastal plain regions. Therewas an inverse linear response of Benghal dayflower emergence and plantingdepth, with no emergence occurring at a planting depth of 12 cm. A fieldsurvey of Benghal dayflower emergence revealed that 42% of plantsestablished from a depth of 1 cm in the soil profile, with 7 cm being themaximum depth from which seedlings plants could emerge. This suggests thatPRE herbicides must remain in the relatively shallow depths of the soilprofile to maximize control of germinating seedlings. Subterranean seedswere less sensitive than aerial seeds to S-metolachlor, theprimary means of controlling this species in cotton. There were nodifferences between the germination of aerial and subterranean seed inresponse to treatment with diclosulam.
