Soil microbial effects on weed seedbank persistence: current knowledge and applications for weed management

Chapter 13. The use of microbe–seed interactions for weed management has been variously discussed over the last few decades, and soil microbes have been demonstrated to play an important role in affecting weed seedbank persistence and weed demography. However, very few weed management applications based on such interactions have so far been successfully tested under field conditions. This chapter provides an up-to-date summary of what is known about direct interactions between buried weed seeds and soil-borne microbes. The principal mechanisms of microbial attack of seeds, the roles of abiotic environmental factors and of biotic interactions in modulating microbe–seed interactions, and seed defence mechanisms underlying weed seed resistance to microbial decay are herein discussed. In addition, how these different aspects can affect weed management applications, via soil inoculation with seed-pathogenic microbes, the manipulation of environmental conditions to promote seed decay processes, and the weakening of seed defences against microbial attack is also discussed. These approaches can be deployed alone or in combination, but combinational approaches may be more promising when designing weed management applications. As shown in this chapter, due to the availability of modern molecular microbial methods, remarkable progress has been made in understanding seed defences and defence syndromes and mechanisms of microbial attack. However, the underlying processes in the field are still only very poorly understood, and a more detailed conceptual framework of how soil-borne seed-decaying microorganisms, weed seeds and their seed-borne microflora, and their environment interact with each other must be developed to facilitate the development of more reliable weed management options.