Agronomic implications of diflufenzopyr application in peanut: transient physiological responses and sustained yield performance

Abstract Low-dose applications of certain herbicides have been hypothesized to induce physiological responses that conserve water and reduce aflatoxin contamination risk in peanut ( Arachis hypogaea L.). Motivated by reported leaf rolling following diflufenzopyr application, this study evaluated whether herbicide-induced stomatal closure and biomechanical changes could serve as a water-saving mechanism during late-season stress. Farm field, rainout shelter plot, and greenhouse experiments were conducted under irrigated and drought conditions to quantify the impacts of herbicide treatment on gas exchange, soil water potential, stem water potential, and leaf biomechanics. Herbicide application in well irrigated plots unexpectedly led to a short-term increase in transpiration, stomatal conductance, and photosynthesis without impacting plant physiological capacity or soil drying rate. However, herbicide application under drought conditions accelerated soil drying and promoted a more rapid physiological decline of plants in drier plots. However, stem water potential and leaf inclination data suggest only temporary disruption in stomatal regulation post-treatment, and after leaves had mechanically compensated to the stress by folding, physiological recovery was seen. Despite these physiological interruptions, responses were ultimately transient and not sustained more than a few days, and there was no significant yield or aflatoxin impacts measured in any treatments. These results revise the initial hypothesis of herbicide-induced water conservation by revealing a more complex, context-dependent interaction between plant water status herbicide response, and agronomic implications.