The effect of injury on whole-plant senescence: an experiment with two root-sproutingBarbareaspecies

Abstract

Although disturbance is able to reset the ageing clock of plants, it is so harmful to plant fitness that resprouting serves, at best, only to alleviate slightly the signs of senescence. Thus, in terms of whole-life seed production, injured plants were not more successful than uninjured ones in the two studied species. Indeed, in these species, injury only slightly postponed or decelerated senescence and did not cause effective rejuvenation.

Enforced Clonality Confers a Fitness Advantage

“…B. vulgaris occupy man-made, ruderal habitats (e.g., arable land, urban habitats, roadside ditches) that are subjected to frequent, severe anthropogenic disturbance, whereas B. stricta occurs in more natural habitats (i.e., pond banks, river alluvia, (Dvořák, 1992 ), that experience naturally occurring disturbance). Both are short-lived herbs typically reproducing once in their lifetime and behaving as biennials, but in certain conditions reproducing repeatedly and behaving as short-lived perennials (MacDonald and Cavers, 1991 ; Dvořák, 1992 ; Martínková et al, 2016 ). During the first year of life, these plants remain vegetative, with rosettes overwintering to the next growing season, when they form leafy flowering stalks.…”

“…During the first year of life, these plants remain vegetative, with rosettes overwintering to the next growing season, when they form leafy flowering stalks. Both species are usually non-clonal, but enforced clonality has been reported from them (Martínková et al, 2008 , 2016 ). In particular, after fragmentation of the root system, they are able to form adventitious buds on roots, successfully regrow and finish the reproductive cycle.…”

“…In particular, after fragmentation of the root system, they are able to form adventitious buds on roots, successfully regrow and finish the reproductive cycle. B. vulgaris regenerates from roots more vigorously than B. stricta (Martínková et al, 2016 ). Both species form persistent seed banks and are able to germinate throughout the year (Hintikka, 1988 ; Baskin and Baskin, 1989 ; Martínková, pers.…”

“…These two root fragments were each 6 cm long but differed in diameter and position in the root system. Six centimeters fragments were found to be able to successfully regenerate in both species (Martínková et al, 2016 ). Thus, the first fragment would be cut from the main root, specifically from the topmost part of the root directly under the hypocotyl.…”

“…In terrestrial ecosystems, enforced clonality has been reported from arable land, with species displaying it receiving attention as weeds (Kefford and Caso, 1972 ; McIntyre, 1972 ; Klimešová et al, 2008 ). It has also been documented in ruderal habitats, where short-lived species survive severe disturbance and some new individuals establish from root fragments (Klimešová et al, 2008 ; Martínková et al, 2016 ). Enforced clonality, however, has importance in other contexts as well, including habitats with natural soil disturbances such as landslides, scree, and water erosion (Hess, 1909 ), colonization of new areas, spread of invasive plants (Bailey et al, 2009 ; Lin et al, 2012 ; Monty et al, 2015 ), and vegetatively propagated crops and ornamentals (Shepherd et al, 2013 ; de Souza et al, 2014 ; Birlanga et al, 2015 ).…”