Contrasting effects of freezing-stress memory on biomass production among herbaceous plant species

Abstract

Prior exposure to freezing can increase the subsequent freezing tolerance of plants and reduce the severity of injury. However, it is unknown how freezing memory influences plant productivity. We investigated the effects of repeated freezing events over multiple seasons on the biomass of Bromus inermis, Lolium perenne, Festuca rubra, Plantago lanceolata, and Poa pratensis. The plants were exposed to different combinations of freezing in the early spring, late spring, or fall (2017), as well as the following spring (2018); control plants were frozen only once, along with all of the other treatments, during the spring of 2018. Bromus inermis that experienced every freeze, and the plants frozen in both the early and late spring, had higher biomass than the controls. Similarly, Poa pratensis plants frozen in both the early and late spring had higher biomass than the controls. In contrast, Festuca rubra plants frozen in early spring and fall had lower root biomass than the control plants, and Lolium perenne plants that experienced every freeze had lower root biomass than the controls. Variation among species in repeated freezing responses could have important consequences for the relative abundances of herbaceous species in northern temperate regions.