Pre-harvest glyphosate application during wheat cultivation: Effects on wheat starch physicochemical properties

Authors: MALALGODA, MANEKA - North Dakota State University; Ohm, Jae-Bom; RANSOM, JOEL - North Dakota State University; HOWATT, KIRK - North Dakota State University; SIMSEK, SENAY - North Dakota State University; GREEN, ANDREW - North Dakota State University

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2019
Publication Date: 12/23/2019
Citation: Malalgoda, M., Ohm, J., Ransom, J.K., Howatt, K., Simsek, S., Green, A. 2020. Pre-harvest glyphosate application during wheat cultivation: Effects on wheat starch physicochemical properties. Journal of Agricultural and Food Chemistry. 68(2):503-511. https://doi.org/10.1021/acs.jafc.9b06456.
DOI: https://doi.org/10.1021/acs.jafc.9b06456

Interpretive Summary: Glyphosate was the most widely used herbicide in the world from 1996 to 2014. It is also commonly used as a drying agent to aid harvest during wheat cultivation. It is generally applied approximately seven days prior to harvest when the plant is at ripe stage. Starch is an important grain component that influences processing and end-product quality in wheat. No extensive research has been published on effect of the application of glyphosate on grain quality in hard red spring wheat. The objective of this study was to investigate the influence of application time of glyphosate on physical and chemical properties of starch in hard spring wheat. Two wheat cultivars were grown in three locations. Glyphosate was applied individually at the early stage (soft dough stage) and the ripe stage (commercial standard) in the grain ripening and maturation period. Upon harvest, wheat samples were analyzed for starch characteristics including starch molecular weight, granule size, digestibility and pasting properties. The results indicate that treatment of glyphosate affected starch properties. Especially, the effect on wheat starch characteristics was more pronounced when glyphosate was applied at the soft dough stage of maturity. This information will be a valuable reference to clarify the effect of glyphosate on starch properties and processing and end-product quality in hard red spring wheat.

Technical Abstract: The objective of this study was to determine how pre-harvest glyphosate timing affects wheat starch physicochemical properties. Two wheat cultivars were grown in three locations and glyphosate was applied at the soft dough stage (early application) and the ripe stage (commercial standard). Upon harvest, starch molecular weight, granule size, digestibility and pasting properties were studied. The proportion of B-type starch granules was lower in treated samples, although starch molecular weight was not affected. Rapidly digestible starch content was highest when glyphosate was applied at the ripe stage, and lowest in the control, and vice versa for slowly digestible starch. Flour pasting viscosity was significantly higher in samples treated at the soft dough stage in comparison to samples treated at the ripe stage and the control. Overall, the effects on wheat starch physicochemical characteristics was more pronounced when glyphosate was applied at the soft dough stage of maturity.