Dissertations and Theses @ UNI
Availability
Open Access Thesis
Keywords
Desert plants--Mexico--Chihuahua (Chihuahua); Germination; Annuals (Plants); Desert plants; Germination; Mexico--Chihuahua (Chihuahua);
Abstract
Seeds of five winter annuals, Eschscholzia mexicana Greene, Eriogonum abertianum Torr. var. abertianum Torr., Eriogonum abertianum Torr. var. ruberrimum Gandoger, Eriogonum rotundifolium Benth., and Eriogonum trichopes Torr., native to the Chihuahuan Desert, were tested for their germination responses relative to constant and fluctuating temperatures, light and dark sensitivity, and innate dormancy. The effects of aqueous leachates from Larrea tridentata (DC.) Cov., on germination and initial hypocotyl growth of the above Eriogonum taxa were also investigated. Eriogonum taxa germinated at constant temperatures ranging from 6° to 20°c, although their optima were at 10° and 13°c. E. trichopes showed highest germination in a 10°/30°c (16 hr/8 hr) fluctuating thermoperiod, while the remaining Eriogonum taxa tested either failed to respond or yielded very low germination percentages. At 10°/20°c (16 hr/8 hr) fluctuating thermoperiod, the Eriogonum taxa germinated but with low percentages. E. a. abertianum and E. a. ruberrimum were positive in their germination response to light, while E. rotundifolium was negative at 15°c constant temperature. Trichopes germination was not significantly affected by light or dark conditions. Three concentrations of aqueous Larrea leaf and twig leachates (10%, 5%, and 1%) significantly reduced germination and hypocotyl growth of all Eriogonum taxa, but 1% leaf leachates did not affect germination of E. rotundifolium and E. trichopes, nor did this concentration significantly reduce the length of E. a. ruberrimum and E. rotundifolium hypocotyls.
E. mexicana seeds failed to germinate under all the conditions which stimulated other Eriogonum taxa to germinate. Scarification, acid soaking, and leaching of the seeds proved ineffective to break dormancy, as were stratification, heat and cold pretreatments. This differential response suggests that at least two groups of winter A-2 annuals exist in the Chihuahuan Desert, those that are opportunistically responsive to environmental stimuli, and an innately dormant group geared to subtle and complex environmental stimuli.
Year of Submission
1974
Degree Name
Master of Arts
Department
Department of Biology
First Advisor
Paul D. Whitson
Second Advisor
E. Russel TePaske
Third Advisor
John C. Downey
Date Original
1974
Object Description
1 PDF file (44 leaves)
Copyright
©1974 Andreas George Christou
Language
en
File Format
application/pdf
Recommended Citation
Christou, Andreas George, "Germination Ecology of Five Chihuahuan Desert Winter Annuals" (1974). Dissertations and Theses @ UNI. 2344.
https://scholarworks.uni.edu/etd/2344
Comments
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