Bioherbicidal activity of Sinapis alba seed meal extracts

Authors: MORRA, MATTHEW - University Of Idaho; POPOVA, INNA - University Of Idaho; Boydston, Rick

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2018
Publication Date: 5/1/2018
Citation: Morra, M., Popova, I., Boydston, R.A. 2018. Bioherbicidal activity of Sinapis alba seed meal extracts. Industrial Crops and Products. 115:174-181. https://doi.org/10.1016/j.indcrop.2018.02.027.
DOI: https://doi.org/10.1016/j.indcrop.2018.02.027

Interpretive Summary: Seed meal from yellow mustard (Sinapis alba L.) is a by product of mustard oil production and has been shown to be phytotoxic to weeds. Active constituants in seed meal that contribute to herbicidal activity vary with each batch. In addition, large quantities of seed meal are required for weed suppression and are logistically difficult to haul and spread. Our objective was to develop an efficacious bioherbicide by producing a S. alba seed meal extract. A 30% methanol extract was obtained from seed meal that resulted in a powder that could be dissolved in water and applied to weeds using a conventional sprayer. Weed control with extract solutions were compared to solutions containing SCN-, 4-OH benzyl alcohol, or 4-OH phenyl acetonitrile at concentrations equivalent to those in the extract. When applied before weed emergence or after emergence, SCN- and extracts were the most active solutions on Powell amaranth, a broadleaf weed and green foxtail, a grass weed. Application of SCN- solutions at concentrations equivalent to those in the extract controlled weeds similar to the extract. Little or no herbicidal activity was observed on both weed species following application of 4-OH benzyl alcohol or 4-OH phenyl acetonitrile, indicating that SCN- is the primary compound responsible for herbicidal activity. Development of a bioherbicide based on extracting and concentrating SCN- from yellow mustard seed meal is feasible, especially if scale up activities focus on eliminating the need for alcoholic extractants and yield higher active ingredient products.

Technical Abstract: Although seed meal from yellow mustard (Sinapis alba L.) is a potential tool for controlling weeds as a consequence of contained glucosinolate substrates that are enzymatically hydrolyzed to produce phytotoxic products, use is limited by batch-to-batch variability and logistical constraints. Our objective was to develop an efficacious bioherbicide by producing a S. alba seed meal extract. An extract was obtained using 30% methanol, concentrated by rotary evaporation, and freeze dried to produce a powder that was redissolved in water before PRE and POST testing on greenhouse grown Powell amaranth (Amaranthus powellii) and green foxtail (Setaria viridis). Companion bioassays with separate solutions containing SCN-, 4-OH benzyl alcohol, or 4-OH phenyl acetonitrile at concentrations equivalent to those in the extract were performed. When applied pre- (PRE) or postemergence (POST), SCN- and extracts were the most active solutions on both weed species. The highest rate tested of SCN- of 2.8 kg ha-1 applied PRE controlled Powell amaranth 98% and green foxtail 84%, compared to the highest rate of extract that controlled Powell amaranth 97% and green foxtail 82%. POST application of the extract was less effective as compared to SCN- solutions, with SCN- showing 97% control of Powell amaranth and 71% control of green foxtail as compared to the extract displaying only 46% control of Powell amaranth and 23% control of green foxtail. Little or no herbicidal activity was observed on both weed species following PRE or POST application of 4-OH benzyl alcohol or 4-OH phenyl acetonitrile. Development of a bioherbicide based on extracting and concentrating SCN- from S. alba seed meal is feasible, especially if scale up activities focus on eliminating the need for alcoholic extractants and yield higher active ingredient products.