Dormancy Changes and Fate of Some Annual Weed Seeds in the Soil

Abstract

Seeds of common cocklebur (Xanthium pensylvanicumWallr.), jimsonweed (Datura stramoniumL.), ivyleaf morningglory [Ipomoea hederacea(L.) Jacq.], giant ragweed (Ambrosia trifidaL.), yellow foxtail[Setaria lutescens(Weigel) Hubb.], and velvetleaf (Abutilon theophrastiMedic.) were buried in the soil at depths down to 15.2 cm in November 1966. Seeds of jimsonweed, ivyleaf morningglory, giant ragweed, yellow foxtail, velvetleaf, common ragweed (Ambrosia artemisiifoliaL.), and Pennsylvania smartweed (Polygonum pensylvanicumL.) were buried 2.5 and 10.2 cm below the surface in October 1968. Seeds were exhumed for periodic laboratory analyses of dormancy changes. All species except ivyleaf morningglory and common cocklebur germinated better in light than in darkness after at least one winter of burial in the soil. Seeds decayed faster at 2.5 cm below the soil surface than at 10.2 cm, but some viable seeds of all species were recovered from both depths after 3 years. The development or maintenance of hard seeds was considered the principle mechanism for seed survival for 3 years in these species.