DOT Project Number:  90-00-LRTF-019

Fiscal Year:  2000

Award:  $3,801.60

Principal Investigator:  Wade Williams, Department of Biology, University of Northern Iowa, wbigbison@gmtel.net

Summary Report:

GERMINATION, EMERGENCE AND EARLY GROWTH OF SPARTINA PECTINATA

Spartina pectinata is frequently omitted from lowland prairie restorations because the seed often fails to grow when planted, and inclusion is limited to plugs of young plants. Anecdotal reports indicated improvement of seed germination following stratification. The effects of seed stratification on the germination of S. pectinata seed were systematically studied. Seed was obtained from both relict populations of plants and germplasm plants as defined by Englert and White (1977). Seed from 5 different collections were subjected to 4 different seed stratifying treatments: imbibed-chilled (1 C for 15 to 45 days); imbibed-frozen (-12 C for 4 to 7 days); or dried-warmed (23 C for 120 days); or aged (4 C for 1.5 to 2.5 years). Control (unstratified) seed for all trials was fresh, dried-chilled seed of the same collection, stored in a refrigerator at 4 C. In addition, seed from 4 collections planted in soil were subjected to 2 different seed stratifying methods (imbibed-chilled, imbibed-frozen) under greenhouse conditions. Emergence of germinating seedlings was monitored for post-emergence damping-off. Also, seedlings from 2 collections were grown in the greenhouse and growth measurements were made weekly for 6 weeks after emergence from the soil. Control seed ranged in average viability from 66.5% (±7) to 99% (±1), in average germination from 59.5% (±7) to 94% (±2.2), and in average emergence from 38.5% (±3.8) to 84.5% (±6.8). The stratification treatments did not improve these values. Longer stratification periods at 1 C for imbibed-chilled seed increased the germination percentage in the early phase of germination, this early increase was also reflected in coleoptile emergence from the soil. Total germination and emergence at the end of the trials were the same as the control. Stratifying seed by imbibed-freezing, dried-warming, or aging up to 1.5 years had no effect on its germination, though control seed germinated significantly better than 2.5-year old seed. Germination rates varied in collections from different sites. Post-emergence damping-off was not observed for any seed collection, but mildew became a problem for seed stratified by imbibed-chill beyond 45 days. For both relict and germplasm plants, the total length of leaves and roots steadily increased during the first 6 weeks. The majority of growth was below ground. Average seed depth decreased during early growth, rising several seed thicknesses from an average planting depth range of 0.62 cm (±0.11) to 0.69 cm (±09). Endosperm starch levels steadily decreased through week 4 and were depleted by week 5. Six week-old seedlings had an average total shoot length range of 30.40 cm (±5.89) to 33.32 cm (±4.71) and an average total root length range of 139.40 (±39.40) cm to 169.11 cm (±52.42). It can be concluded from this study that Spartina pectinata should be included in prairie restoration projects, as viable seed will germinate readily with or without stratification.