Cool-Season Turfgrass Germination and Morphological Development Comparisons at Adjusted Osmotic Potentials.

One of the major factors limiting seed germination and seedling development in a low-input, low-maintenance environment is soil moisture availability.  Correlating seed germination rates with turfgrass drought tolerance/avoidance mechanisms in an established population may be misleading.  Seed from different species can utilize different soil moisture conditions for successful establishment, perhaps related to variations in imbibition efficiency, or possibly that some species require less moisture to complete the germination process than others.   The objective of this research was to identify germination characteristics of cool-season turfgrass species experiencing water duress conditions.  Cool-season turfgrass species evaluated were tall fescue [Schedonorus phoenix (Scop.) Holub], hard fescue (Festuca brevipila Tracey), red fescue (F. rubra ssp. rubra L.), chewings fescue [Festuca rubra L. ssp. fallax (Thuill.) Nyman], perennial ryegrass (Lolium perenne L.), and Kentucky bluegrass (Poa pratensis L.).  Osmotic potential treatments were 0.0, -0.4, -0.8, -1.2, and -1.6 MPa.  At all osmotic potentials, perennial ryegrass had greater occurrences of germination than all other species evaluated.  Radicle production of perennial ryegrass was also greater than all other species at -0.4, -0.8, and -1.2 MPa treatments.  Perennial ryegrass was the only species with enough plumule length observations of 5mm or greater for statistical analysis at -1.2 MPa, while red fescue had the greatest plumule length at all other treatment levels.  Based on  germination occurrences and initial radicle and plumule length development at decreasing osmotic potentials, utilizing perennial ryegrass in seed mixtures of low-input, low-moisture turfgrass plantings can promote early establishment during periods of potential low soil moisture conditions.