Title: SOIL SEED BANK DYNAMICS OF GIANT RAGWEED (AMBROSIA TRIFIDA L.) AND THE ROLE OF SOIL FUNGI IN SEED DECAY PROCESSES [ABSTRACT] Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 10, 2006
Publication Date: July 18, 2006
Citation: Fu, X., Williams, M.M.II, Chee-Sanford, J.C. 2006. Soil seed bank synamics of giant ragweed (Ambrosia trifida l.) and the role of soil fungi in seed decay processes [abstract]. Association for Tripical Biology and Conservation. Available: http://atbc.xtbtg.ac.cn. Technical Abstract: Management of weeds is essential for successful crop production all over the world. Buried seed reserves, commonly referred to as the soil seed bank, are a major source of future plant emergence. Weed seeds in particular, are resilient and highly adaptive, and their abundance and persistence in soil makes weed control a continuing challenge. Management of seed banks is an important component of long-term and sustainable weed management strategies, however information on mechanisms of seed bank dynamics is lacking. In particular, the role of soil microorganisms in affecting seed fate is not well understood and may be important in regulating seed banks, for example, by causing seed decay or stimulating germination. To address investigation of seed bank dynamics and seed-microbe interactions, we are conducting a field study in the midwestern U.S. state of Illinois at an agronomic location with an extensive seed bank of an annual weed species, giant ragweed (Ambrosia trifida L.). In situ assessments of seed fate, along with characterization of microbial populations associated with decaying seeds, will be examined in both natural and artificial seed banks over one year. Thus far, significant depletion of the seed bank of Giant Ragweed due to seed decay occurred in the natural soil seed bank. In natural soil, the decayed seeds account for different percentage in total seed amount at different soil depth. In early spring, decayed, damaged and germinated seed depletion is 48%, 42% and 10% respectively. In summer, the proportions of decayed and damaged seeds are 51% and 32%. We hypothesize the importance of fungi as key microorganisms in causing seed decay. Using automated ribosomal intergenic spacer analysis (ARISA), fungal communities in the soil and on decaying seeds will be characterized. According to the preliminary research of ARISA, the composition of microbial communities on the surface of decayed seeds is different from those of other seed categories. This research will improve our understanding of weed seed bank dynamics and the fundamental factors that can affect seed fate in nature. The work will also provide useful information for development of future seed bank management strategies in agricultural ecosystems.