EFFECTS OF CLIPPING AND NITROGEN-FERTILIZATION ON TILLER DEVELOPMENT AND FLOWERING IN KENTUCKY BLUEGRASS

One hundred cores (10 x 10 x 12 cm) of Kentucky bluegrass (Poa pratens is L. 'Nugget') were removed from an established seed field, potted, a nd subjected to two clipping treatments after seed harvest (clipping a t 2.5 cm to simulate straw and mechanical stubble removal and clipping at 7.5 cm to simulate straw removal) and two fertilizer treatments (s olutions with and without the equivalent of 100 kg ha-1 of N). The pla nts were then subjected to a cold treatment (98 d at 2.5-degrees-C) to induce flowering. Added N increased the number of large tillers forme d before the cold treatment, and produced similar increases in the num ber of initiated tillers and flowering shoots. Added N resulted in lar ger inflorescences with more spikelets. Close clipping (2.5 cm) did no t affect tillering or flowering shoot density, but reduced stem length and resulted in smaller inflorescences with fewer spikelets.