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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #268636
Title: Evaluation of factors that influence Benghal dayflower (Commelina benghalensis) seed germination and emergence

Author
item SABILA, M.H. - University Of Georgia
item GREY, T.L. - University Of Georgia
item Webster, Theodore
item VENCILL, W.K. - University Of Georgia
item SHILLING, D.G. - University Of Georgia

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/22/2011
Publication Date: 1/1/2012
Citation: Sabila, M., Grey, T., Webster, T.M., Vencill, W., Shilling, D. 2012. Evaluation of factors that influence Benghal dayflower (Commelina benghalensis) seed germination and emergence. Weed Science. 60:75-80.

Interpretive Summary: Benghal dayflower(BD), also known as tropical spiderwort, has recently become troublesome in the US due to its natural tolerance to glyphosate. An herbaceous perennial in tropical climates, BD in North America establishes annually from seed. Therefore, greater understanding of the factors that regulate germination and establishment will help improve effective management strategies. Maximum aerial seed germination occurred at 30C, while maximum subterranean seed germination occurred at both 30C and 35C. BD was not tolerant to salt, indicating that this exotic species is not likely to become problematic in the brackish wetlands and natural areas of the coastal plain. No BD emergence occurred at a planting depth of 12 cm. A field survey of emergence depths revealed that 42% of plants established from a depth of 1 cm in the soil profile, with a maximum depth of 7 cm. This suggests that PRE herbicides must remain in the relatively shallow depths of the soil profile to maximize control of germinating seedlings. Subterranean seeds were less sensitive than aerial seeds to s-metolachlor, the primary means of controlling this species in cotton. There were no differences between the germination of aerial and subterranean seed in response to treatment with diclosulam. Future research concerning the factors that govern the physical dormancy imposed by the seed coat may allow for a greater understanding of germination and emergence of this species.

Technical Abstract: A perennial species in its native range, Benghal dayflower (BD) in North America establishes annually from seed. BD has the unique ability to produce aerial and subterranean flowers and seeds; information on how various environmental factors affect BD aerial and subterranean seed germination and emergence in the US is lacking. Maximum aerial seed germination occurred at 30C, while maximum subterranean seed germination occurred at 30C and 35C. Germination at 40C was delayed relative to optimum temperatures. The seed coats were mechanically disrupted to evaluate the response of seeds to temperature in the absence of physical dormancy. The physical dormancy imposed by the seed coat may require additional study. BD was not tolerant to =10mM NaCl, indicating that this exotic species is not likely to become problematic brackish marshes and wetlands of the coastal plain. There was an inverse linear response of BD emergence and planting depth, with no emergence occurring at a planting depth of 12 cm. A field survey of emergence depths revealed that 42% of plants established from a depth of 1 cm in the soil profile, with a maximum depth of 7 cm. This suggests that PRE herbicides must remain in the relatively shallow depths of the soil profile to maximize control of germinating seedlings. Subterranean seeds were less sensitive than aerial seeds to s-metolachlor, the primary means of controlling this species in cotton. There were no differences between the germination of aerial and subterranean seed in response to treatment with diclosulam.