Title: Freezing stress influences emergence of germinated perennial grass seeds Authors
Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 25, 2012
Publication Date: February 25, 2013
Citation: Boyd, C.S., Lemos, J.A. 2013. Freezing stress influences emergence of germinated perennial grass seeds [abstract]. 66th Annual Meeting of the Society for Range Management, February 3-7, 2013, Oklahoma City, Oklahoma. Paper No. 112. Technical Abstract: In sagebrush rangelands perennial bunchgrasses are typically seeded in fall and a high proportion of planted seeds germinate prior to winter onset but fail to emerge in spring. Our objectives were to evaluate freezing tolerance of germinated but non-emergent bluebunch wheatgrass seeds under laboratory conditions. In experiment 1, bluebunch wheatgrass seeds were planted in control pots and compared to seeds planted at early, mid or late germination stages. Pots from each treatment were placed in a grow room maintained at 12hr 40min light/11hr 20min dark photoperiod, with a constant temperature of 22oC for 30 days either immediately or following a 30 day freeze (-7.5oC ) In experiment 2, germinated bluebunch wheatgrass seeds were planted in pots that were left non-frozen or were frozen (-7.5oC ) for a specified duration prior to a 30 day period in the grow room. Emergence density and tillers/seedling were quantified for both experiments. Freezing reduced or eliminated seedling emergence at all stages of germination (p < 0.001) and tiller density was reduced by at least 50% (p < 0.001). Maximum reduction in seedling density was realized within four days of initiation of freezing and tillers/seeding were reduced 30 – 70% with > 6 days of freezing (p = 0.001). Our data indicate that freezing-associated mortality of germinated bluebunch wheatgrass seedlings can be extremely high and suggest that management practices to reduce pre-winter germination of seeds could improve subsequent emergence and seeding success.