1. Greens-type Poa annua was found to be intermediate in relative salinity tolerance rankings for cool-season turfgrass relative salinity tolerance rankings for cool-season turfgrass species during seed germination and vegetative growth. Some species during seed germination and vegetative growth. Some experimental lines exhibited nearly equal salinity tolerance to experimental lines exhibited nearly equal salinity tolerance to that of perennial ryegrass ‘Charger II’ that of perennial ryegrass ‘Charger II’ and creeping bentgrass ‘Mariner’. and creeping bentgrass ‘Mariner’. We thus conclude that greens-type We thus conclude that greens-type Poa annua possesses moderate Poa annua possesses moderate salt tolerance and some salt tolerance and some particular lines have potential to particular lines have potential to be used on golf courses with be used on golf courses with moderate salt problems affecting moderate salt problems affecting turf establishment and turf establishment and maintenance. maintenance. Golf courses and home lawns are increasingly being irrigated with effluent Golf courses and home lawns are increasingly being irrigated with effluent water as the availability of fresh water becomes limited. water as the availability of fresh water becomes limited. Greens-type Poa annua is being developed into a commercial turfgrass. Greens-type Poa annua is being developed into a commercial turfgrass. Literature suggests that among cool-season turfgrass species, Poa annua Literature suggests that among cool-season turfgrass species, Poa annua is very sensitive to salinity stress, while perennial ryegrass (Lolium is very sensitive to salinity stress, while perennial ryegrass (Lolium perenne L.) is tolerant, creeping bentgrass (Agrostis stolonifera L.) perenne L.) is tolerant, creeping bentgrass (Agrostis stolonifera L.) moderately tolerant, and Kentucky bluegrass (Poa pratensis L.) moderately sensitive (Carrow and Duncan, 1998). moderately sensitive (Carrow and Duncan, 1998). Research indicates substantial variation in salinity tolerance exists in greens-type Poa annua and numerous experimental lines possess greens-type Poa annua and numerous experimental lines possess moderate-to-good salinity tolerance(Dai, 2006). moderate-to-good salinity tolerance. (Dai, 2006). Introduction Evaluate salinity tolerance of greens-type Poa annua during Evaluate salinity tolerance of greens-type Poa annua during seed germination and vegetative growth relative to other cool- seed germination and vegetative growth relative to other cool- season turfgrass species including creeping bentgrass, season turfgrass species including creeping bentgrass, Kentucky bluegrass, and perennial ryegrass. Kentucky bluegrass, and perennial ryegrass. ObjectivesObjectives Nine greens-type Poa annua exp. lines, representing the range of salinity Nine greens-type Poa annua exp. lines, representing the range of salinity tolerance detected within Poa annua (Dai, 2006), Kentucky bluegrass tolerance detected within Poa annua (Dai, 2006), Kentucky bluegrass ‘Northstar’ & ‘Moonlight’, creeping bentgrass ‘Mariner’, ‘Seaside II’ & ‘Northstar’ & ‘Moonlight’, creeping bentgrass ‘Mariner’, ‘Seaside II’ & ‘Penncross’, and perennial ryegrass ‘Charger II’. ‘Penncross’, and perennial ryegrass ‘Charger II’. Seeds were germinated on agar media with NaCl Seeds were germinated on agar media with NaCl levels of 0 (control), 5, 10, 15, and 20 dS m -1. levels of 0 (control), 5, 10, 15, and 20 dS m -1. Exp. I & II design: RCBD with 3 replications. Exp. I & II design: RCBD with 3 replications. Materials and Methods Annual, weedy type Perennial, greens-type Evolution Under mowing management References: Carrow, R. N., and R. R. Duncan. 1998. Salt affected turfgrass sites: Assessment and management. Ann Arbor Press, Chelsea, MI. Dai, J. 2006. Salinity tolerance of greens-type Poa annua L. M.S. thesis. The Pennsylvania State Univ., University Park. Comparison among 5 representative grasses in VD, RD, and LRL with increasing salinity during vegetative growth. Comparison among 5 representative grasses in VD, RD, and LRL with increasing salinity during vegetative growth. dS m -1 Entry Verdure dry weight (g) Entry dS m -1 Root dry weight (g) Conclusions and Summary Salinityeffects on seed germination and vegetative growth of Salinity effects on seed germination and vegetative growth of greens-type Poa annua L. (annual bluegrass) relative to other cool-season turfgrass species Jing Dai, Maxim J. Schlossberg, David R. Huff; Dept. of Crop & Soil Sciences, Penn State Univ., University Park, PA 16802 Greens-type Poa annua also exhibited intermediate salinity tolerance during vegetative growth. Greens-type Poa annua also exhibited intermediate salinity tolerance during vegetative growth. Extremely high shoot density Tolerance to close mowing Aggressiveness under shady & trafficked conditions Data collected on final germination Data collected on final germination percentage (FGP) and germination rate (GR). percentage (FGP) and germination rate (GR). Mowing heights: Poa annua and creeping bentgrass: ¼ inch or 6.4mm Poa annua and creeping bentgrass: ¼ inch or 6.4mm Perennial ryegrass: ½ inch or 12.7 mm Perennial ryegrass: ½ inch or 12.7 mm Kentucky bluegrass: 1 inch or 25.4 mm Kentucky bluegrass: 1 inch or 25.4 mm Exp. I & II design: Split plot design with 3 replications. Exp. I & II design: Split plot design with 3 replications. Whole plot factor: salinity levels-1.2 (control), 5, 10, and 15 dS m -1 Whole plot factor: salinity levels-1.2 (control), 5, 10, and 15 dS m -1 Split plot factor: grasses Split plot factor: grasses Data collected on clipping yield dry weight, Data collected on clipping yield dry weight, verdure dry weight (VD), root dry weight (RD), verdure dry weight (VD), root dry weight (RD), and the longest root length (LRL). and the longest root length (LRL). Data subjected to ANOVA and Fisher’s LSD. Data subjected to ANOVA and Fisher’s LSD. Pooled data (Exp I & II) are shown. Pooled data (Exp I & II) are shown. Results and Discussion Seed germination study Vegetative growth study Seed germination study Visual comparison among 3 representative grasses: perennial ryegrass ‘Charger II’, greens-type Poa annua PSU 99-9-21, and Kentucky bluegrass ‘Moonlight’. Visual comparison among 3 representative grasses: perennial ryegrass ‘Charger II’, greens-type Poa annua PSU 99-9-21, and Kentucky bluegrass ‘Moonlight’. FGP and GR decreased linearly or quadratically with increasing salinity for all grasses. Greens-type Poa annua experimental lines were intermediate in the range of predicted salinity levels to reduce FGP or GR by 50%. FGP and GR decreased linearly or quadratically with increasing salinity for all grasses. Greens-type Poa annua experimental lines were intermediate in the range of predicted salinity levels to reduce FGP or GR by 50%. Vegetative growth study Longest root length (cm) dS m -1 Entry PSU 99-9-21 Moonlight 0 dS m -1 Charger II 5 dS m -1 10 dS m -1 15 dS m -1 20 dS m -1