The effects of desiccation on broad‐leaved dock (Rumex obtusifolius) and curled dock (Rumex crispus) root fragment regeneration

Abstract

Fresh root fragments of Rumex crispus and Rumex obtusifolius, which initially contain 65–70% moisture, progressively lose moisture when desiccated under conditions matching summer weather in southeast England. The likelihood of shoot emergence and the time it took in glasshouse conditions were both affected by desiccation, with R. crispus the most affected up to 48 hr and R. obtusifolius slower to emerge after 48 hr. These effects converged after longer desiccation periods, and R. crispus entirely failed to emerge after 120 hr. The dry weight of emerged shoots was not significantly different between the species until they were desiccated for 96 hr, after which R. obtusifolius dry weight was significantly reduced. In outdoor trials, desiccation for 24 or 48 hr had a lesser effect on emergence in either species when fragments were planted at the soil surface or at up to a depth of 10 cm, compared to deeper plantings, but emergence was significantly lower in plantings at 15 or 20 cm. Emergence delays were not significantly different between the species until they were planted at 15 or 20 cm, when R. obtusifolius was slower to emerge than R. crispus, an effect exacerbated by increasing desiccation. Similar interactions of increasing soil depth and desiccation were found in reductions in dry weight, number of tillers and leaf area, with R. obtusifolius generally, but not exclusively, better able to withstand more extreme trial conditions. Our findings suggest that control of these highly troublesome weeds can be assisted by appropriate agricultural practices, notably exposing cut fragments to drying conditions followed by deep burial.

Regeneration and growth in crowns and rhizome fragments of Japanese knotweed (Reynoutria japonica) and desiccation as a potential control strategy

“…This is similar to Pennisetum macrourum, an African perennial grass (Harradine, 1980) and Equisetum arvense (Marshall, 1986;Husby, 2013) which can regenerate from one node, showing that other rhizomatous species follow similar patterns in which regeneration can occur from a single node. Additionally, Alshallash & Hatcher (2020) identified the presence of rhizome tissue as key to regeneration in two Rumex species.…”

“…Smaller rhizomes and rhizomes in the zero node category reached dry mass faster than larger fragments and crowns, but 30 -38 days was sufficient for even the larger plant fragments to reach constant dry weight. The desiccation experiment was conducted via air drying, rather than use of an oven as in other desiccation experiments, e.g., Alshallash & Hatcher (2020), to purposely simulate what might be possible for home-owners with a small to moderate infestation. The experiment suggests that if carefully removed and left to air dry for approximately 38 days, then even medium sized crowns are likely to have died and be unable to produce new emergences or regenerate.…”

“…Drying angiosperms to equilibrium with air (dry weight) kills virtually all of them (Alpert, 2006). Desiccation as a management technique for aquatic invasive non-native species has highlighted that such species can survive even significant drying (Coughlan et al, 2018), while terrestrial plants have been shown to be more susceptible to desiccation as a potential control method (e.g., Rumex species; Alshallash & Hatcher, 2020). However, no experiments focusing on how R. japonica responds to a period of air drying and replanting were identified in the literature.…”