Date of Award:

5-1980

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Wildland Resources

Department name when degree awarded

Range Ecology

Committee Chair(s)

Martyn M. Caldwell

Committee

Martyn M. Caldwell

Committee

Herman Wiebe

Committee

Jon Takemoto

Abstract

Damage to primary photosynthetic reactions caused by environmental stress can be assessed by measurement of chlorophyll fluorescence induction in intact leaves. This approach was applied in studies of ultraviolet-B photoinhibition of photosynthesis in Pisum sativum L. and Rumex patientia L. leaves. At ultraviolet-B dose rates insufficient to cause inhibition of net photosynthesis, changes in the magnitude of fluorescence transients did occur, which suggested direct effects on chloroplast pigments in Pisum and inhibition of photosynthetic electron transport between the photosystems in both species. Leaves of these two species subjected to a much higher dose rate had a significant reduction of net photosynthesis and changes in the magnitude of fluorescence transients that indicated partial loss of water-splitting capability and direct effects on chloroplast pigments. Ultraviolet radiation-induced changes of photosynthetic thylakoid membranes may be ultimately responsible for these disruptions of the primary photosynthetic reactions.

Checksum

90423e4a0bf7a56702179c8a882b24cd

Share

COinS