Degree Type

Dissertation

Date of Award

1989

Degree Name

Doctor of Philosophy

Department

Horticulture

First Advisor

Richard J. Gladon

Second Advisor

David S. Koranski

Abstract

The effects of low-oxygen atmospheres on the germination of Impatiens wallerana Hook. f. were tested and related to germination in the plug-production system. The cultivars tested could germinate partially under water, but the germination rate was slower and the germination meantime was longer for all cultivars but one. There was little variability among cultivars germinated on blotter paper, but much greater variability was found when the seeds were germinated under water. Although impatiens seeds could germinate when submerged, they were not able to germinate in seven days at 0% oxygen, and essentially no germination occurred in 3% oxygen. At oxygen concentrations between 20% and 7%, percent germination and the coefficient of uniformity of germination declined linearly, and the germination rate and germination meantime changes were curvilinear. A high oxygen concentration (20%) was best for optimum germination of impatiens;When seeds were placed on the surface of a plug soil medium, the germination percentage of five of the six cultivars was not affected by either the medium type or the medium moisture level. However, burial of the impatiens seeds 2 mm deep significantly reduced germination and emergence of all cultivars. Seedling emergence from the plug soil medium was more severely reduced than germination percentage in all cases, and this indicates that post-germinative events are more severely curtailed by seed burial than germination events. The germination response of the buried seeds was intermediate to the responses reported for the previous two experiments;Ethanol and lactate accumulated during anaerobic conditions (100% nitrogen gas). Lactate rose to a level twice that of air-exposed seeds, and ethanol accumulated to levels 10 times that of seeds germinated in air. Malate declined in the seeds under anaerobic conditions. Seeds submerged in 40 ml water did not excrete detectable levels of ethanol to the imbibition medium. Ethanol accumulated rapidly in the water of seeds in 200 [mu]l of water. (Impatiens seeds could germinate in 40 ml but not in 200 [mu]l of water.) The reason impatiens seeds can germinate in a large water volume but not in 100% nitrogen gas is not clear, but these results are evidence in support of the hypothesis that ethanol is not excreted as efficiently into a gaseous environment as it is into an aqueous one.

DOI

https://doi.org/10.31274/rtd-180813-12399

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Paul Thomas Karlovich

Language

en

Proquest ID

AAI9003536

File Format

application/pdf

File Size

135 pages

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