Performance of integrating reduced trifluralin doses with nonchemical treatments on weed management and dill ( Anethum graveolens L.) yield

In order to evaluate the effect of reduced doses of trifluralin in integration with non-chemical management treatments on weeds, essential oil yield and composition of dill ( Anethum graveolens L.), a 2-year study was conducted in East Azarbaijan, Iran in 2020–2021. The study was conducted as factorial experiment based on randomized complete block design with four replications. The first factor was trifluralin use at four levels (non-use, 480, 720 and 960 g ai ha −1 ) and the second factor was non-chemical weed management treatments consisted of using the living mulch of fenugreek ( Trigonella foenum-graecum L.) (FLM) and bitter vetch ( Vicia ervilia (L.) Willd. (VLM), wheat straw mulch (WSM), one time hand weeding (OHW) and without non-chemical management (control). The results indicated that at all trifluralin doses the weed biomasses in OHW and WSM treatments were lower than those in FLM and VLM. The relative ranking of non-chemical weed management treatments for weed biomass reduction and essential oil yield of A. graveolens L.was OHW > WSM > FLM and VLM. The results of GC–MS analysis indicated that the main chemical constituents of essential oil (carvone, limonene and dill apiole) were influenced differently by trifluralin use and non-chemical weed management treatment. We can conclude that recommended dose of trifluralin could be replaced with reduced doses of trifluralin in integration with non-chemical treatments in order to improve the weed control efficacy and essential oil yield of A. graveolens L. in a sustainable production system.