Exploiting Soybean and Flaxseed Meal Byproducts as Safe Weed Management Approaches in Onion Field

The intensive and repeated use of chemical herbicides has led to the emergence of herbicide-resistant weeds, which, in addition to their environmental impacts, also pose significant threats to human and animal health. This study aimed to explore the potential of oilseed industrial wastes, specifically soybean and flaxseed meals, as safe and environmentally friendly bioherbicides for controlling weeds associated with onion crops. Two field experiments were conducted along two successive winter of 2020/21 and 2021/22. Treatments involved foliar spray of soybean and flaxseed meals in three different concentrations (15, 30 and 45%), mulching of seed meals, oxyfluorfen herbicide, two hand hoeing and untreated weedy check. The findings demonstrated that all weed control treatments significantly reduced weed density, biomass and nutrient uptake. Two hand hoeing, oxyfluorfen herbicide and the mulching of soybean and flaxseed meals alternated in the top rank for weed control, showing minimal significant differences among them. Following these effective treatments, soybean meal extracts at 45 and 30% exhibited notable weed control compared to the weedy check. The greatest enhancement in onion growth, yield characteristics and bulb quality was observed with the application of hand hoeing, soybean and flaxseed meal mulching treatments, with no significant differences between them. High-Performance Liquid Chromatography (HPLC) fractionation of both meals identified various phenolic acids at different concentrations. Practically, these safe efficient treatments proved progress on chemical herbicide. Hence, onion farmers are advised to apply soybean and flaxseed meals mulching safe treatments as alternative to harmful chemical herbicides under all experimental conditions.