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Australian Herbicide Resistance Initiative (AHRI)

Mechanical scarification technique breaks seed coat-mediated dormancy in wild oat (Avena fatua)

Wild oat is a herbicide resistance-prone global weed species that causes significant economic losses in dryland and horticultural agriculture.

As a result, there has been a significant research effort in controlling this species.

A major impediment to this research is the seed coat-mediated dormancy of wild oat, requiring a labor-intensive incision or puncturing of the seed coat to initiate seed germination.

This study defines the most efficient settings of a mechanical thresher to overcome wild oat seed dormancy and then validates these settings using multiple populations collected from the Western Australian grain belt.

We also compare the effects of rapid mechanical scarification and known germination stimulus tactics such as scarification with sulfuric acid (H2SO4), partial endosperm removal, sandpaper scarification of the seed coat, and immersion in sodium nitroprusside (NO donor SNP) solution on wild oat seedling growth rate. Threshing treatment of 1,500 rpm for 5 s provides equivalent germination compared with manually puncturing individual wild oat seeds, with no difference in seedling relative growth rate. The mechanical scarification of seeds using the thresher resulted in greater germination (66%) than H2SO4 scarification (0%), partial endosperm removal (10%), sandpaper seed coat scarification (25%), and exposure to NO donor SNP (34%). This study demonstrates that the physical dormancy of wild oat can be rapidly overcome using a commercially available mechanical thresher.

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