Mahdiyeh Amirinejad

This study was conducted to assess the efficacy of the bio-herbicide Dominus (based on allyl isothiocyanate, applied at 280 L ha⁻¹) for weed management in onion production under both greenhouse and field conditions in the southern region of Kerman Province, Iran, during the 2021–2022 growing season. In the greenhouse experiment, the effect of Dominus application on seven weed species was investigated using a factorial experiment based on completely randomized design with four replications, while the field trial was arranged in a randomized complete block design with two treatments: Dominus application and a non-treated as a control. Under greenhouse conditions, Dominus significantly reduced the germination of all seven weed species including Malva neglecta Wallr., Amaranthus retroflexus L., Chenopodium album L., Lolium rigidum Gaud., Phalaris minor Retz., Avena ludoviciana Durieu., and Cuscuta campestris L. at the 1% probability level. In the field, Dominus provided complete (100%) control of the dominant weed Cyperus rotundus L. and markedly decreased the biomass of the other weed species. Onion yield in the Dominus-treated plots (130.75 t ha⁻¹) did not differ significantly from the weed-free control (131.55 t ha⁻¹), whereas the untreated weedy check exhibited an 83% yield reduction, producing only 15.69 t ha⁻¹. Despite its pronounced efficacy achieving total control of purple nutsedge and significant suppression of both broadleaf and narrow-leaved weeds the application of Dominus is recommended solely for use by trained professionals adhering strictly to established safety protocols, owing to potential health and safety hazards associated with its active ingredient.