Comparing Minimum Moisture Requirements of Germinating Turfgrass Species.

The literature is lacking on the genetic capability of specific turfgrass species or cultivars to germinate under drought stress conditions.  Correlating seed germination rates with turfgrass drought tolerance/avoidance mechanisms in an established population may be misleading.  It has been illustrated that seed from different species can utilize different soil moisture conditions for successful establishment.  This may be related to variations in the efficiency with which imbibition occurs, or a reflection of the fact that some species require less moisture to complete the germination process than others.  This study was conducted to compare the differential responses of seeded turfgrass species to varying water potentials simulating a field establishment situation.  Fifty seeds were placed on 3 layers of filter paper in a covered petri dish and treated with mannitol solutions simulating soil moisture levels of 0 (field capacity), -0.4, -0.8, -1.2, and -1.6MPa (permanent wilting point).  Species evaluated were bermudagrass (Cynodon dactylon [L.] Pers.), hard fescue (Festuca brevipila Tracy), and tall fescue (F. arundinacea Schreb.).  Seeds were placed in a seed germinator and germinated seedlings were counted at appropriate time intervals based on Association of Official Seed Analysts (AOSA) guidelines.  Hard fescue germination was significantly greater at -0.8, -1.2, and -1.6MPa, followed by tall fescue and then bermudagrass.  There were no significant differences between species at 0.0 and -0.4 MPa.  During periods of low soil moisture content, seeded hard fescue plantings provide greater potential levels of germination and vegetative cover than tall fescue and bermudagrass seedings.