Date of Award:

5-1975

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Plant Ecology

Committee Chair(s)

Frank Salisbury

Committee

Frank Salisbury

Committee

Inge Dirmhirn

Committee

Martyn Caldwell

Committee

John Evans

Abstract

Several montane plant species and one alpine species were observed to grow under snow, and the seeds of 19 species germinated under snow. The spectral irradiance of light penetrating up to 198 cm of snow was measured with a device employing a photomultiplier tube and a series of interference filters. In deep snow, the measured peak in transmission was near 500 nm, but in older, more shallow snow the peak was at 550 nm. On two occasions measurements were made both before and after sunrise. There was a shift in the spectra toward the longer wavelengths as the sun rose higher in the sky. Grand Rapids lettuce seed germination was promoted by a three hour exposure to the light penetrating 198 cm of snow. Brassica nigra and Brassica kaber seeds responded similarly to longer exposures under deep snow. A light and temperature interaction in seed germination was noted. Other plant light responses observed under snow were chlorophyll synthesis, inhibition of shoot elongation, and leaf unfolding.

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