Alfalfa cultivars respond differently to seed germination inhibition by Kentucky bluegrass

Allelopathic effects may be a contributing factor in the mixed success of legume re-establishment in Kentucky bluegrass ( Poa pratensis L.)-dominated pastures. Under controlled conditions, we evaluated whether aqueous shoot or root extracts from Kentucky bluegrass would affect seed germination for three alfalfa ( Medicago sativa L.) cultivars after a 7-day incubation period. Both shoot and root extracts had an inhibitory effect on alfalfa seed germination for all cultivars. AAC Trueman was the least affected and AC Caribou the most affected by aqueous Kentucky bluegrass root extracts, suggesting that the capacity for rejuvenating old pastures may vary among alfalfa cultivars.