Physically damage seeds of non-woody plants before sowing: freshwater wetlands

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • Three studies evaluated the effects – on emergent, non-woody plants typical of freshwater wetlands – of physically damaging their seeds before sowing. All three studies were in greenhouses or laboratories in the USA.








  • Germination/emergence (3 studies): Two replicated, controlled studies (one also randomized) in greenhouses in the USA found that rubbing seeds of herbaceous plants with sandpaper before sowing had no significant effect on their germination rate. One replicated, randomized, paired, controlled study in a laboratory in the USA found that removing the sac-like seed coating before sowing typically increased, and did not reduce, the germination rate of sedges Carex spp.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A replicated, controlled study in the early 1990s in a laboratory in Colorado, USA (Thullen & Eberts 1995) found that rubbing hardstem bulrush Scirpus acutus seeds with sandpaper had no significant effect on their germination rate. Germination rates did not significantly differ between seeds that had been rubbed between sandpaper before incubation (0–11% germination) and seeds that had not been rubbed (0–14% germination). Methods: Thirty-two sets of 10–50 hardstem bulrush seeds were incubated in flasks of fresh water at 10/25°C or 18/22°C (night/day temperatures). Of these, 16 sets had been rubbed 20 times with sandpaper immediately before incubation, whilst 16 sets had not. All seeds had been collected in August 1991 from two wild populations, stored in the laboratory for >5 months, and sterilized immediately before the experiment. The study does not clearly report the length of monitoring (probably between six and twelve weeks).

    Study and other actions tested
  2. A replicated, randomized, controlled study in 1994–1995 in a greenhouse in Florida, USA (Ponzio 1998) found that rubbing sawgrass Cladium jamaicense seeds with sandpaper had no significant effect on their germination rate. Germination rates did not significantly differ between seeds rubbed with sandpaper then soaked in water (44% germinated) and seeds only soaked in water (44% germinated). For reference, the germination rate of seeds that were neither rubbed nor soaked was 55%. Methods: In September 1994, three-year-old sawgrass seeds were sprinkled onto 18 trays of sterilized soil (100 seeds/tray). Six trays were planted with seeds rubbed with sandpaper for one minute then soaked in water for 24 h. Six trays were planted with seeds only soaked in water. Six trays were planted with untreated seeds (neither rubbed nor soaked). The trays were placed in random positions in a greenhouse and watered daily until no more germination occurred.

    Study and other actions tested
  3. A replicated, randomized, paired, controlled study in 1997 in a laboratory in Utah, USA (Jones et al. 2004) found that removing the sac-like coating of sedge Carex spp. seeds before sowing never reduced the germination rate, although the precise effect depended on light conditions after sowing. In three of three comparisons involving seeds germinating in light, exposed seeds had a higher germination rate (43–95%) than seeds still in their sac (26–88%). In two of three comparisons involving seeds germinating in the dark, exposed seeds had a statistically similar germination rate (2–12%) to seeds still in their sac (1–8%). In the other comparison, exposed seeds had a higher germination rate (40%) than seeds still in their sac (31%). Methods: Two-year-old seeds of beaked sedge Carex utriculata and Nebraska sedge Carex nebracensis were sown into a total of 384 petri dishes (192 dishes/species; 32 seeds/dish), then incubated in the laboratory. In 192 random dishes, the sac-like coating of the seeds had been removed by tumbling the seeds in sandpaper. In the other 192 dishes, the coating had not been removed. Dishes were allocated to various other treatments (including germination in light vs dark, and different pre- and post-sowing temperature regimes). Each incubator shelf received four random dishes of each treatment combination. Germination rates, as a percentage of viable seeds, were recorded for each dish 36 days after sowing.Environmental effects on germination of 

    Study and other actions tested
Please cite as:

Taylor N.G., Grillas P., Smith R.K. & Sutherland W.J. (2021) Marsh and Swamp Conservation: Global Evidence for the Effects of Interventions to Conserve Marsh and Swamp Vegetation. Conservation Evidence Series Synopses. University of Cambridge, Cambridge, UK.

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Marsh and Swamp Conservation

This Action forms part of the Action Synopsis:

Marsh and Swamp Conservation
Marsh and Swamp Conservation

Marsh and Swamp Conservation - Published 2021

Marsh and Swamp Synopsis

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