Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Abstract Only
Publication Acceptance Date: October 2, 2010
Publication Date: January 26, 2011
Citation: Williams, R.D., Bartholomew, P.W. 2011. Variation of hairy vetch seed weight alters germination and seedling growth response to an allelochemical. Proceedings of Southern Weed Science Society. 64:134. Interpretive Summary: Abstract only.
Technical Abstract: The inhibition of seed germination by an allelochemical is generally greater in small seeds than in large seeds. This response may have significant impact on weed control by allelopathic cover crops where the small-seeded weeds would be controlled more effectively than large-seeded species. In our studies, hairy vetch (Vicia villosa Roth.) seed were separated into three classes that varied in seed weight (large, 54 mg; medium, 40 mg; and small, 26 mg) to compare their germination response to coumarin at 10-3 and 10-5 M. There was no significant difference in germination at 10-5 M concentration with respect to seed size. However the 10-3 M concentration delayed and reduced seed germination and this effect was more noticeable in the small seed class. Expressed as a percent of control, germination for large, medium and small seed was 72%, 76%, and 55%, respectively, and germination of the small seed was delayed by two days. There was no difference in shoot lengths between the 10-5 M coumarin and the control treatments for either the small or medium sized seed, but there was a difference in the large seed. Shoot length was significantly reduced by the 10-3 M coumarin regardless of seed size. Root length appeared to be more sensitive to coumarin than shoot length. The 10-5 M coumarin did not reduce root length in either the small or medium sized seed, but did in the large seed. Coumarin at 10-3 M reduced root length regardless of seed size. These results confirm those reported in the literature based on seed of a number of species with different size seed. Small seed do appear to have a greater sensitivity to an allelochemical, and this sensitivity is selective within a species with respect to its small versus large seed. This selection pressure could have significant impact on the weed community over time.