Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2011
Publication Date: 6/1/2012
Citation: Williams, M.M. II, Schutte, B.J., Yim, S. 2012. Maternal corn environment influences wild-proso millet (Panicum miliaceum) seed characteristics. Weed Science. 60:69-74. Interpretive Summary: Interest in finding new technology to manage weeds has fueled research on whether modification of the agroecosystem could deplete weed seedbanks, the main source of future weed infestations. One aspect of this approach may be through manipulation of the maternal environment; conditions under which seed-producing plants grow. We studied how different corn environments influenced the seed produced by wild-proso millet. Results showed that poorly competitive corn hybrids produced wild-proso millet seed that was most germinable. The impact of this work is that it advances our knowledge of weed seed biology and may someday help develop novel tools for managing weeds. For instance, wild-proso millet seedbanks may be reduced after corn harvest by stimulating germination through light tillage or irrigation. Emerged seedlings could then be killed with a non-selective herbicide or additional tillage.
Technical Abstract: Evidence suggests the maternal environment of the developing weed has important implications to seed physiology of certain species. This work quantified the extent to which within-crop variability in the maternal environment altered wild-proso millet seed coat color and germinability. In field studies conducted in 2006 and 2007, wild-proso millet was grown in four sweet corn hybrids representing a range of market types and differing in canopy architecture. Germination assays were conducted four to six weeks after crop harvest. Seed coat color and tone (i.e. lightness) were quantified from scanned images of seed using a Red Green Blue (RGB) color model. Germinability of wild-proso millet varied with sweet corn hybrid. Seed from wild-proso millet plants maturing in hybrid Quickie were seven to nine percent less dormant than seed maturing in Mystic and Rocker, hybrids capturing 26% more light than Quickie. Polymorphism in seed coat color among maternal environments was narrower than observed among wild-proso millet biotypes in previous work; however, some differences in RGB scores were observed. Correlation analysis of crop phenomorphological traits and germinability indicated a maternal environment with a longer vegetative period and more upright crop leaves produced wild-proso millet seed with lower germinability. These same maternal environments produced wild-proso millet seed that was reduced in individual RGB scores and seeds were generally darker, compared to smaller crop plants. This work shows that within-crop variation in the maternal environment of sweet corn influences germinability of wild-proso millet, and to a lesser extent, seed coat color.