Viability of Kentucky Bluegrass Pollen (Poa pratensis L. ‘Newport’) as Influenced by Collection Time and Temperature¹

Attempting to determine reasons for extreme variability in germination of Kentucky bluegrass pollen, we studied temperature and time effects, harvesting panicles from a seed field at 8:00 A.M., subjecting them to temperatures ranging from 21 C to 49 C, collecting pollen at hourly intervals for germination on agar medium and subsequent microscopic examination. Pollen viability decreased with increased exposure time and with higher temperature. The average germination of pollen collected at 8:00 A.M. was approximately 50%, so we collected pollen in the field at half hour intervals from 6:00 to 8:00 A.M. and at hourly intervals thereafter until 4:00 P.M. Germination of pollen exceeded 80% from 6:00 to 7:30 A.M., but declined to 50% by 8:00 A.M. and to less than 2% by 9:00 A.M. Pollen collected each hour from 11:00 A.M. to 4:00 P.M. would not germinate.