Date of Award:

5-1971

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Plants, Soils, and Climate

Department name when degree awarded

Botany

Committee Chair(s)

Frank Salisbury

Committee

Frank Salisbury

Committee

William F. Campbell

Committee

Herman H. Wiebe

Committee

Inge Dirmhirn

Committee

David R. Walker

Abstract

Studies were conducted to determine the influence of different temperatures (25, 10, 0, or -5 C) upon plant growth and cell ultrastructure, and to determine if physical changes within cells might block growth activities even though individual biochemical processes were potentially active.

Secale cereale L. was found to be most hardy, followed by Cynodon dactylon (L) Pers. and Paspalum notatum Flugge, whose responses were quite similar. Secale grew normally at 25 and 10 C, with reduced activity at 0 C and a slight delay before resuming normal growth when placed at 25 C again. All three species were killed at -5 C. Cynodon and Paspalum grew normally at 25 C, but showed reduced growth and slowed recovery at 10 C much like Secale did at 0 C. At 0 C, they ceased all activity and not all plants of either species recovered after being placed at 25 C again. Recovery required several days.

Chloroplasts from Secale showed less clustering, but considerably more swelling at colder temperatures than either Cynodon or Paspalum.

Vacuolar debris within cells of all three species increased as temperatures were reduced, Secale again showing the greatest response.

Mitochondria and ribosomes did not show any significant change at reduced temperatures in any of the species.

Dictyosomes decreased in all three species as temperature was reduced, possibly signifying reduced metabolic activities.

Rough endoplasmic reticulum increased in all three species as temperature was lowered, indicating increased potential for protein production or a reduced rate of degradation for the rough endoplasmic reticulum.

Download

Included in

Botany Commons

Share

COinS

Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .