Pre-sowing Seed Treatments, Seed Coats, and Metabolic Activity of Lehmann Lovegrass Seeds

Data from both field and laboratory studies have suggested germination of Lehmann lovegrass (Eragrostis lehmanniana Nees.) caryopses (seeds) can be improved by various pre-sowing seed treatments. Effective treatments include moistening and drying, oven-drying, scarification, and pre-chilling on a moist substrate. The increased germination may be due to improved seed-coat permeability or to a change in the metabolic state of the seed. A growth chamber study was undertaken to determine if pre-treating air dry Lehmann lovegrass seeds with moistening, oven-drying, or mechanical scarification increased: (1) inetabolic activity upon remoistening; (2) seed-coat permeability relative to moisture imbibition; and (3) percent germination in low concentrations of oxygen (O₂). Lehmann lovegrass seeds were pre-treated and immediately following treatment samples were either: (1) imbibed in darkness at 24 C and analyzed after 9 hours for adenosine triphosphate (ATP) content and after 24 hours for percent germination; (2) imbibed in darkness at 24 C and analyzed after 0, 6, and 18 hours for moisture content; (3) imbibed for 37 hours at 24 C in atmospheres containing either 5, 10, or 21% O₂ and analyzed for percent germination; or (4) viewed with a scanning electron microscope to evaluate damage to seed coats. Treated seeds germinated better and contained more ATP than untreated seeds. Oven-dried, scarified, and moistened plus oven-dried seeds germinated the best, while scarified and moistened plus oven-dried seeds contained the most ATP. Rate of moisture imbibition was increased by pretreatments. After 6 hours of imbibition, scarified, ovendried, and moistened plus oven-dried seeds contained significantly more moisture than air-dried seeds. After 18 hours the differences were not as large. Treated seeds germinated best in atmospheres of 5, 10, and 21% O₂, but germination was poorest in the 5% O₂. Seed coats appeared affected by treatments. Scarified seeds appeared scratched and the gelatinous coating surrounding the seeds appeared loosened and torn from moistening and oven-drying.