Heat seeds of non-woody plants before sowing: freshwater wetlands

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

Study locations

Key messages

  • One study evaluated the effects – on emergent, non-woody plants typical of freshwater wetlands – of heating their seeds before sowing. The study was in a greenhouse in the USA.








  • Germination/emergence (1 study): One replicated, randomized, controlled study in a greenhouse in the USA found that sawgrass Cladium jamaicense seeds dipped in hot water or dried in an oven before sowing had a similar germination rate to seeds that had not been heated.

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, randomized, controlled study in 1994–1995 in a greenhouse in Florida, USA (Ponzio 1998) found that heating sawgrass Cladium jamaicense seeds had no significant effect on their germination rate. Seeds dipped in hot water before soaking in room-temperature water had a 50% germination rate, whilst seeds dried in an oven before soaking in room-temperature water had a 40% germination rate. Seeds only soaked in room-temperature water had a 44% germination rate: not significantly different from either of the heat treatments. For reference, the germination rate of seeds that were neither heated nor soaked was 55%. Methods: In September 1994, three-year-old sawgrass seeds were sprinkled onto 24 trays of sterilized soil (100 seeds/tray). Eighteen trays were planted with seeds that had been soaked in 25°C water for 24 h. Seeds in twelve of these trays had been heated before soaking: six steeped in 80°C water for 3 min, and six dried in an oven at 80°C for 24 h. Ten trays were planted with untreated seeds (neither heated 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
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.

Where has this evidence come from?

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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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