Extreme Ionic and Temperature Effects on Germination of Weeping Alkaligrass (Puccinellia distans), Nuttall's Alkaligrass (Puccinellia nuttalliana) and Kentucky Bluegrass (Poa pratensis)

Abstract

The introduced species weeping alkaligrass, and the native species Nuttall's alkaligrass, two of the most salt-tolerant C3 grasses found in arid and semiarid environments of western North America, occur within the Grande Ronde valley of eastern Oregon. Both species occur as weeds within Kentucky bluegrass seed fields and subsequently as grass seed contaminants. Two separate germination experiments were conducted to understand better the seed germination biology of these two species compared to Kentucky bluegrass under negative water potentials or high temperature conditions. Results of these studies indicate that although all three species benefited from an ionic enhancement associated with NaCl, weeping alkaligrass was the most drought and salt tolerant of the three species. Dry seeds of weeping alkaligrass were also particularly tolerant to high temperatures with no differences in germination at temperatures below 50 C, indicating that seed viability under nonirrigated field conditions should be unaffected by high soil temperatures. Under soil temperature conditions as high as 40 C, moist Kentucky bluegrass seeds had the greatest germination rates, indicating that this species should benefit from irrigation more than the other two species.