Heat seeds of non-woody plants before sowing: freshwater wetlands
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
Background information and definitions
Heating seeds before planting can help to break seed dormancy and encourage germination. Seeds of some species (with physiological dormancy) must experience high temperatures before germinating, in order to break down chemicals that inhibit germination or stop the production of these chemicals. For other species (with physical dormancy), heat can increase the permeability of the seed coat to water and gases, which are essential for germination. For a database of seed dormancy class by species, see Baskin & Baskin (2014).
To be summarized as evidence for this action, studies must have explicitly compared the performance of treated and untreated seeds. Studies that simply report the performance of treated seeds are not summarized here. Studies do not have to be in flooded/saturated soils, as long as they involve wetland-characteristic species,
Baskin C.C. & Baskin J.M. (2014) Seeds: Ecology, Biogeography and Evolution of Dormancy and Germination, Second Edition. Academic Press.
Supporting evidence from individual studies
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