| Abstract Detail
Ecological Section Fitch, Elizabeth [1], Walck, Jeffrey [1], Hidayati, Siti [1]. Temporal aspects of the light requirement for seed germination of two rare Paysonia species (Brassicaceae) in considering management protocols. Paysonia perforata (Rollins) O'Kane & Al-Shehbaz and P. stonensis (Rollins) O'Kane & Al-Shehbaz are winter annuals endemic to middle Tennessee that grow in open, frequently disturbed habitats such as agricultural fields in floodplains. Seeds of both species were collected during peak dispersal in late April/early May and given 0-16 weeks of white light at simulated summer temperatures before placement in darkness at early autumn temperatures. Seeds of P. perforata and P. stonensis required >2 and >8 weeks, respectively, of white light exposure on continuously moist substrate for >50% of total germination to occur in darkness, but both needed >12-14 weeks on alternating wet/dry substrate. In the field, the highest percentages of germination in darkness occurred for both species when seeds were placed under soybean/Johnson grass from late May to mid-July and then exposed to white light following harvesting until mid-August when they were buried. Thus, soil disturbances such as plowing occurring after late July could bury photostimulated seeds and potentially deplete the soil seed bank since seedlings would fail to emerge >2.0 cm beneath the soil surface. On the other hand, timing for fulfillment of the light requirement for germination is reduced when the substrate is continuously moist, which might correspond to the increase in precipitation predicted by one global climatic change model. Under current and future scenarios, the planting and harvesting times for corn or silage best fits the life cycle and seed photoecology of both Paysonia species.
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1 - Middle Tennessee State University, Department of Biology, Murfreesboro, Tennessee, 37132
Keywords:
Photoecology
Soil seed bank
seed dormancy
Agroecosystem
Climatic change.
Presentation Type: Oral Paper
Session: 43-7
Location: Salon F - Austin Grand Ballroom/Hilton
Date: Wednesday, August 17th, 2005
Time: 9:30 AM
Abstract ID:94 |
