Mustard seeds as a safe tool in different application methods for controlling broomrape weed infesting faba bean crop

Broomrape is one of the most destructive parasitic weeds limiting faba bean productivity. Mustard has gained attention as a sustainable weed management tool due to its allelopathic potential and richness in bioactive secondary metabolites. Two field experiments were applied in two successive winter seasons to examine different mustard application methods, including foliar spraying, soil incorporation of mustard seed powder and mustard plant intercropped with faba bean crop to identify the most effective strategy for suppressing broomrape infestation and improving faba bean performance. Hence, this study contained ten treatments. Seven of them included different mustard application methods including two interplanting treatments of mustard with faba bean plants in two planting densities. Additionally, two treatments of adding mustard powder beside each faba bean plant (10 and 15 g/plant). Three mustard extract treatments at three successive rates: 15, 30 and 45 g/L. The remaining three treatments included glyphosate-isopropylammonium, Roundup 48% WSC herbicide at 0.18 L ha^- 1 and two control treatments included hand pulling twice and unweeded check.

Glyphosate is the most effective treatment for controlling broomrape, followed by mustard extract 45, 30 g/L, hand pulling, mustard seed powder at 15 g/plant and mustard Interplanting 3 plants/hill, respectively. In addition, glyphosate herbicide, treatments of mustard extract at 45, 30 g/L, hand pulling, mustard extract 15 g/L as well as mustard seed powder at 15 g/plant, respectively achieved the best results in all faba bean yield and yield traits comparing to other treatments.

Spraying of mustard extract at 45 and 30 g/L was the most effective method of mustard applications to control broomrape as a safe method in comparing with other mustard methods of applications. The bioherbicidal activity of mustard may be attributed to phenolic and flavonoid contents and glucosinolates. HPLC fractionation of mustard seed powder aqueous extract revealed that ferulic, chlorogenic and ellagic acids were the most abundant phenolic acids that may be attributed with the inhibitory herbicidal effect of mustard seed powder.