Broad- and narrow-leafed weeds are one of the main challenges that hinder the barley (Hordeum vulgare L.) production expansion due to their competitiveness. The latest study aimed to use different methods that have a perpetual effect on weeds in barley fields. A field experiment on barley ensued during crop seasons 2021–2022 and 2022–2023 in the north of Najaf Province, Iraq. Eight combinations and two treatments of the experiment (manual weed control, herbicides, and seeding rate) progressed using a randomized complete block design with 10 replications. Results showed significant differences between treatments and combinations. Saracen, Axial, and weed-free, with a seeding rate of 160 kg ha^-1, provided the lowest weed density and the highest weed control efficiency compared with the control (120 kg ha^-1). The use of Saracen, Axial, and weed-free, with a seeding rate of 160 kg ha^-1, showed the utmost weed control. Based on HPLC analysis of Saracen and Axial residues, the active substances Florasulam and Pinoxaden appeared to be less than the detected level in the grains and straw of barley, which confirms their safety for human and animal consumption. Using herbicides that inhibit acetolactate synthase (ALS) and Acetyl coenzyme-A carboxylase (ACCase), combined with increasing seeding rate, boosts efficient weed control in barley fields.

Keywords: Barley (H. vulgare L.), weed population, seed rate, herbicides, weed control, acetolactate synthase (ALS), Acetyl coenzyme-A carboxylase (ACCase)

Key findings: Herbicide use that inhibits the biosynthesis of amino and fatty acids with increasing seeding rate enhanced the efficiency of weed control in barley (H. vulgare L.).