Potential Fire Effects on Seed Germination of Four Herbaceous Species

Abstract

Fire is a natural component of grasslands throughout the world, but information on the impact of fire on seed germination is lacking. Our objective was to determine the influence of different levels of heat on Johnsongrass (Sorghum halepense), Lamb's quarters (Chenopodium album), partiridge pea (Cassia chamaecrista), and rough pigqeed (Amaranthus retroflexus) seed germination under laboratory conditions. Seeds were heat-treated in four replicates for 120 seconds at 200, 400, 600, 800, and 1000 degrees Farenheit, plus a control. Germination was determined on 100 randomly selected seeds of each species from each heat treatment and control replicates. None of the species had increased germination after being subjected to heat treatments when compared to controls. In all species, germination was reduced when treatment temperature reached 600 degrees Farenheit, and germination was eliminated at 800 and 1000 degrees Farenheit. Laboratory evaluations indicate the heat generated by prescribed fires is adequate to sterilize seed not buried below the soil surface. These responses support the general recommendation to burn during the winter's dormant season to promote forbs for wildlife species by burning under cooler conditions to reduce heat damage to seeds of desirable plant species.