EMERGENCE FROM BURIED SEED AND GERMINATION OF EXHUMED SEED OF FALL PANICUM

Abstract

Nylon mesh envelopes containing 200 seeds of fall panicum (Panicum dichotomiflorum Michx. var. geniculatum (Wood.) Fern.) and 20 cc sterile soil were buried 1–20 cm below the surface of silt loam and gravelly loam in a farmer’s field in November 1971. In April 1972 exhumed seeds germinated from 73.4 to 91% in 17 °C dark 10 h/27 °C light 14 h, the percentage increasing with depth. Seedling emergence during May-September 1972 averaged 48, 45 and 5% from 1-, 2-, and 5-cm depths in silt loam but 1, 19, and 10% from the same depths in gravelly loam and was erratic during the second growing season. No emergence came from 10- or 20-cm depths, nor from any depth after 2 yr. Germination of seed exhumed from the 20-cm depth was 80.75, 37.75, and 10.5% for the silt loam soil, and 46.5, 21, and 2.5% for the gravelly loam soil at sampling times of 12, 29 and 54 mo, respectively. Germination of seed exhumed from shallower depths was less in each instance except from the 5-cm depth in silt loam at 29 mo when it was the same. Potential reproduction (sum of emergence plus subsequent germination) decreased with depth down to the 10-cm level in both soils, but increased again with greater depth (at 20 cm).