Rough Bluegrass Germination Varies with Temperature and Cultivar/Seed Lot

Rough bluegrass (Poa trivialis L.) is being utilized more frequently to overseed bermudagrass (Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy) putting greens and rapid seed germination is necessary for successful establishment. Cultivar and seed lot differences in germination rate and sensitivity to cold may exist. Germina- tion of 10 rough bluegrass cultivars/seed lots was examined in growth chambers at 12- hour day/12-hour night temperatures of 25/15, 20/10, 15/5, and 10/0 °C, and on a bermudagrass putting green at three overseeding dates. Differences in germination among cultivars and seed lots were minimal at 25/15 or 20/10 °C, but substantial at lower temperatures. When seeded on the bermudagrass putting green, differences in germina- tion among cultivars/seed lots were greater at the last seeding date (average daily max./ min. of 16/2.7 °C), than at the first seeding dates (average daily max./min. of 21/6.1 °C). Use of blends of several cultivars or seed lots is suggested to ensure the successful establishment of rough bluegrass when overseeding at low temperatures.