Maternal water stress reduces sensitivity of offspring to herbicides in Amaranthus palmeri (Palmer amaranth)

Abstract

AbstractThe immediate impact of prevailing environmental conditions on sensitivity of weeds to herbicides is well documented but little is known about the effects of parental environments on the responses of progeny to herbicides. It has been suggested that parental plants subjected to abiotic stress may result in progeny with increased tolerance to stresses. We tested this hypothesis by growing two populations of Palmer amaranth (Amaranthus palmeri) from California and Kansas under well‐watered (WW) and water‐deficit (25% of WW treatment) conditions to obtain F1 seeds. We then tested the responses of F1 seedlings to various doses of five herbicides with different modes of action. Dose‐response analysis of visual plant injury, aboveground biomass, and chlorophyll content showed that in 16 out of 30 comparisons, sensitivity to herbicides in A. palmeri progeny originated from a maternally water stressed environment was significantly lower than those obtained from WW plants. Only in one case the progeny from stressed plants was significantly more sensitive to herbicide (saflufenacil) than that from non‐stressed plants, and no differences were observed between the two types of progeny in all other (13) comparisons. The reduced sensitivity in progeny from stressed plants was consistent in terms of the evaluated response variables in population from California with the application of S‐metolachlor, rimsulfuron, and simazine; and in population from Kansas with the application of S‐metolachlor and rimsulfuron. Our study suggests that A. palmeri plants experiencing drought during the season may produce progeny that might be more difficult to control because of an increase in herbicide tolerance endowed through transgenerational effects of water stress.