Silicon nutrition enhances CYP450s‐ and GST‐mediated metabolism of sulfosulfuron in wheat and an invasive weed, Hordeum vulgare subsp. spontaneum

BACKGROUNDAlthough silicon nutrition in crops has been reported to improve growth and herbicide tolerance, the response of crop‐associated weeds has not been studied.RESULTSIn glasshouse studies, co‐applying potassium silicate (K2SiO3) + silicate‐solubilizing bacteria (SSB) synergistically increased wheat and spontaneous barley's silicon content by 2.2‐ and 2.6‐fold, respectively. Based on the median effective dose, it increased wheat (2.2–2.8‐fold) and spontaneous barley (3.5–3.7‐fold) tolerance to sulfosulfuron. With/without silicon nutrition, pretreating plant species with malathion or 4‐chloro‐7‐nitrobenzofurazan made them more sensitive to sulfosulfuron. Without silicon nutrition, cytochrome P450 reductase (1.3 versus 0.7 U g−1), glutathione S‐transferase (1.7 versus 1.2 U g−1), superoxide dismutase (23.7 versus 14.5 U mg−1), and catalase (412.9 versus 311.5 U mg−1) were more active in wheat than in spontaneous barley. All enzymes became more active with silicon nutrition, the increase was higher in spontaneous barley. Field studies conducted at two locations showed that without silicon nutrition and sulfosulfuron, spontaneous barley reduced wheat grain yield by 36.8–41.5%. Without sulfosulfuron, co‐applying K2SiO3 + SSB synergistically increased spontaneous barley biomass by 37.4–76.1%, reducing wheat grain yield by 59.0–62.1%. Without silicon nutrition, sulfosulfuron (40 g ha−1) controlled spontaneous barley by 71.8–98.5%. Furthermore, it controlled spontaneous barley by 18.7–29.9% when K2SiO3 + SSB was co‐applied.CONCLUSIONSilicon nutrition made both plants more tolerant to sulfosulfuron due to the increased activity of enzymes that metabolize herbicides and scavenge reactive oxygen species. It should be avoided in spontaneous barley‐infested wheat fields because it is more beneficial for spontaneous barley and reduces sulfosulfuron efficacy. © 2025 Society of Chemical Industry.