Document: TON-3-31-9

Microcalometric studies on metabolism and germination in response to temperatire for three populations of winterfat (Eurota lanata).

THYGERSON, T.* ¹, D.T.BOOTH ², J.M.HARRIS ¹, L.D.HANSEN ¹ and B.N.SMITH ¹

Brigham Young University, Provo, Utah 84602 ¹
USDA-ARS, Cheyenne, WY 82009 USA ²

Abstract:
Eurotia lanata (Pursh) Moq. (winterfat) is a boreal cold-desert subshrub, seldom more than 2 feet tall, and thrives in dry climates at cooler temperatures. Stem, leaves, and dispersal units called diaspores are covered with a dense mix of short and long white hairs that aid in water retention. It is excellent forage for both wildlife and domestic cattle. Diaspore collections from Matador, Saskatchewan, Canada; Pine Bluffs, Wyoming; and Sterling Colorado were soaked in a tween solution (10%) for 10min. and then in dilute sodium hypochlorite (1%) for 45 minutes, placed on moistened filter paper in petri dishes, and kept in beakers partially submerged in coolant bathes maintained at 0, 5, 10, 15, and 20C to study germination. At the time of radicle emergence (ca. 3mm), seeds were placed in ampules in a microcalorimeter. Heatrate (q) was measured at a given temperature, then a vial containing NaOH was added to measure the rate of CO₂ evolution (R_CO2) for the same tissue at the same temperature. This procedure was repeated for each of the populations at temperatures ranging from 10 to 20C. From these measurements efficiency and predicted specific growth rates were calculated. Optimum temperature for germination, metabolism, and early seedling growth is about 10C. Stress is noted near 20C and 5C. Acclimation during germination had no effect. Differences between the three populations correlated with altitude rather than latitude.

Keywords: Germination, Respiration, Temperature, Winterfat (Eurotia lanata)

This abstract is being presented at: 3:30 PM in session:
REPRODUCTIVE ECOLOGY