Fenclorim Increasing Butachlor Selectivity between Wheat and Roegneria kamoji by Seed Soaking

Roegneria kamojiOhwi (Poaceae), a wild relative plant of wheat which is widely distributed across China, has become a dominant and problematic weed in wheat fields in some regions. We have previously confirmed thatR. kamojiis highly tolerant to foliar-applied acetyl-CoA carboxylase (ACCase) and acetolactate synthase (ALS) inhibitors in wheat (Triticum aestivumL.). The sensitivity ofR. kamojito pre-emergence (PRE) herbicides and the basis of fenclorim increase selectivity to butachlor between wheat andR. kamojiwere evaluated in this study. Screenhouse bioassay showed thatR. kamojiexhibited similar sensitivity to wheat to PRE herbicides at their recommended field doses (RFD); it also showed that buatchlor provides the highest relative control forR. kamoji(53.4% emergence and 81.5% fresh weight reduction, respectively), while it had no impact on seedling emergence of wheat among the six PRE herbicides. When butachlor was applied at four-fold RFD, noR. kamojiseedlings emerged; however, it significantly reduced the above-ground biomass of wheat compared with the non-treated control. Pre-treatment with herbicide safener fenclorim by seed soaking increased the ED10value of butachlor to wheat from 221.8 to 1600.1 g a.i. ha−1, thus increasing the selectivity index from 9.6 to 68.9 between wheat andR. kamoji. The activities of α-amylase activity and protein content during germination, and glutathione-S-transferase (GST) and β-ketoacyl-CoA synthase (KCS) in the seedlings, could be induced by butachlor in both wheat seeds with or without fenclorim pre-soaking. These results suggested that butachlor provides the highest control forR. kamojiand did not affect germination and emergence in wheat. The basis of fenclorim-increased selectivity to butachlor was associated with the induced GST and KCS-mediated enhanced herbicide metabolism in wheat.Keywords:Roegneria kamoji;wheat;herbicide safener;fenclorim;selectivity