Unexpected Benefits: Herbicide Diflufenzopyr's Neutral Impact on Transpiration and Enhanced Plant Performance in Arachis Hypogaea

Authors: Bucior, Erika; Sorensen, Ronald - Ron; McIntyre, Joseph

Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: While herbicides are commonly used in agriculture to induce negative effects on unwanted herbaceous plants, many studies have found that application of sublethal doses of herbicides can enhance plant growth and induce varying physiological responses in a process called herbicide hormesis. Responses may include but are not limited to stimulation of shoot elongation, increase in aboveground biomass, altered protein content, and changes in photosynthetic habit. In peanut (Arachis hypogaea), an application of the herbicide Diflufenzopyr resulted in late season flower termination, inducing short-term determinate plant response resulting in less immature pods at harvest. Application of Diflufenzopyr did not cause dieback or permanent discoloration of leaves but did induce a temporary response of leaf rolling for about 4-5 days. Leaf rolling is a hydronastic mechanism that reduces light interception, transpiration, and leaf dehydration, playing a similar role as osmotic adjustment in maintaining internal plant water status and preventing water loss. Therefore, finding a sub lethal dose of Diflufenzopyr that acts as a stimulant to this hydronastic mechanism or illicit a temporary change in plant habit, could potentially result in a beneficial recovery in terms of plant water status, soil water status, and biomass allocation patterns. We found that in irrigated plots, application of Diflufenzopyr resulted in enhanced physiological functioning that maintained soil moisture, whereas in dryland plots the same application caused an inhibitory response and rapid decline of soil moisture. Application of this herbicide did not result in a straightforward strategy to limit plant transpiration and control soil moisture.

Technical Abstract: Herbicides are often used in farming to control unwanted plants, but research shows that application of small amounts can sometimes boost plant growth, a process known as herbicide hormesis. In peanuts, applying the herbicide Diflufenzopyr stopped late-season flowering, making plants produce fewer immature pods at harvest. This application also caused temporary leaf rolling for about 4-5 days, which is a stress response mechanism that helps the plant conserve water. Whe hypothesized that inducing this plant response could preserve soil moisture by essentially stopping water movement in the plant temporarily. However we discovered that using Diflufenzopyr in irrigated plots improved plant performance and maintained soil moisture, but in dryland plots, it caused soil moisture to drop quickly. Using this herbicide didn't offer a straightforward solution to control plant water loss and soil moisture.