Publications:
1) Second Place Winner of the 1998 Undergraduate Research Competition....hyperlink: 1998 Meeting of Kentucky Academy of Science (Botany Section)
...see abstract below2) Lau, JM and DL Robinson. 1999. Characteristics of Germination in Ageratina altissima. 8th Symposium on The Natural History of Lower Tennessee and Cumberland River Valleys, Land Between The Lakes, March 19-20, 1999, p. 23-24.
3) Lau, JM. 1999. Temperature regulation of seed germination and dormancy in Ageratina altissima. Butler University Undergraduate Research Conference, April 9, 1999, p. 16.
4) Robinson, DL and JM Lau. 1999. Inheritance of Achene Dormancy in White Snakeroot (Ageratina altissima). American Society of Plant Physiologists, Baltimore, MD, July 24-28, 1999....hyperlink:Abstract
5) Lau, JM and DL Robinson. 1999. Continuation of a Study on Inheritance of Achene Characteristics in Ageratina altissima. 85th Annual Meeting, Kentucky Academy of Science, Richmond, KY, Nov. 4-6, 1999.
6) Lau, JM and TA Malkin. 2000. Effects of altered catalase activity on seed germination in tobacco. Butler University Undergraduate Research Conference, April 14, 2000, Indianapolis, IN.
| 1998 KAS abstract: Influence of temperature on seed germination and dormancy in Ageratina altissima. Joann M. Lau* and David L. Robinson, Department of Biology, Bellarmine College, Louisville, KY, 40205. White snakeroot (Ageratina altissima (L.) King & Robinson [Eupatorium rugosum Houtt.]) is a common weed found in the shady margins of woodlands. Seeds of this species germinate in the spring and plants bloom in early autumn. The seeds are conditionally dormant, and therefore likely to be sensitive to fluctuations in temperature. The effect of temperature in breaking seed dormancy and germination was examined using genetic, physiological, and cytological techniques. To study the genetic basis for temperature response, approximately 2000 seeds were screened for different dormancy traits. Seeds were collected, after-ripened, and stored for 18 months at 4oC. Seventy-seven percent of the seeds germinated when imbibed and incubated at 21oC. Remaining seeds were exposed to sequential cycles of cold and given ample time to germinate between cycles. Germinated seeds were planted, grown to maturity, and allowed to reproduce in order to evaluate the progeny. Another experiment showed that seeds stored at 4oC may not need additional cold treatments to germinate if adequate time is given, as no statistically significant differences were observed between continuous cold vs. fluctuating cold vs. the 21oC control. In a third experiment, however, 26% of freshly-harvested seeds kept at 4oC continuously for 60 hours germinated, while only 17% of seeds exposed to 60 hours of cold in five 12-hour increments germinated (significant at P < 0.05). Germinating seedlings were also cytochemically stained for the presence of oxalate oxidase. This enzyme stained positively in two monocot species, but not in A. altissima or another dicot.
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| 1999 KAS Abstract:Continuation of a study on inheritance of achene
characteristics in Ageratina altissima.
Joann M. Lau* and David L. Robinson, Department of Biology, Bellarmine College, Louisville, KY, 40205. Seed dormancy is a powerful means by which plants control when and where they occur. Three major sources for a population's variability for dormancy are genetic diversity, somatic polymorphism, and microsite/ temporal/biological variability. The goal of this research was to explore the relative importance of these sources in regulating achene (seed) germination and dormancy in White Snakeroot (Ageratina altissima (L.) King & Robinson [Eupatorium rugosum Houtt.]). Last year, White Snakeroot achenes were selected for different germination and dormancy traits, grown to maturity and allowed to reproduce. The progeny (achenes) of these selections were then examined for different germination characteristics. Most (54%) of the progeny germinated before any cold treatment, while 12% germinated after a single cold treatment. Although, on average, there were no noticeable differences between the parental groups, there were obvious differences between individual selections. For instance, one plant (from a non-cold-requiring achene) produced achenes that exhibited 100% germination at room temperature, whereas another plant (from an achene that germinated after one cold treatment) exhibited 32%, 20%, and 16% germination after 0, 1, and 2 cold treatments, respectively. Also, the effect of achene size on germinability was examined by partitioning achenes from a single population into four size categories. In one population (even though the weight of large achenes was more than double the smallest) there were no statistically significant differences in cumulative germination between different size categories. Therefore, if there is somatic polymorphism for achene dormancy in White Snakeroot it may involve characteristics other than achene size.
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