Date of Award

12-2016

Level of Access Assigned by Author

Campus-Only Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Ecology and Environmental Sciences

Advisor

Francis A. Drummond

Second Committee Member

David Yarborough

Third Committee Member

Alison Dibble

Additional Committee Members

Michael Day

David Percival

Abstract

In this study, Maine lowbush blueberry (Vaccinium angustifolium), was used to document the functions plants deprioritize when they reproduce, as well as how and why this depriorization occurs. A literature review established that an experimental reduction in reproductive effort—flower removal—consistently resulted in higher values for many traits, such as total vegetative mass, fruit ripening rate, and vegetative development rate, for treated plants relative to control plants, across a range of systems and taxonomic groups. In keeping with these past results, lowbush blueberry clones subjected to a flower removal treatment showed significantly higher values for many of these same traits, as well as for several understudied traits like fruit chemistry and fruit shape, when compared to unmanipulated plants. Trade-off severity varied by year for several traits, such as ripe fruit production rate and leaf area, with severity stronger in years with more adverse weather conditions. Using multiple levels of removal, several traits, including leaf area and fruit titratable acidity, were found to trade off with reproductive effort non-linearly, as predicted by recently proposed ecological theories. Little evidence was found, through a combination of flower removal, defoliation, and fertilization treatments, to support the popular hypotheses that the reproductive trade-offs observed in plants like lowbush blueberry are due to carbon or nitrogen limitation. Instead, results indicated that some reproductive traits, like ripe fruit production rate and titratable acidity, were more limited by innate performance differences amongst reproductive nodes themselves. Using a simulation model, high reproductive effort and poor genetic robustness were indicated as factors that may fundamentally limit fruit set in Maine lowbush blueberry agroecosystems by increasing the occurrence rate of incompatible mating events. Lowbush blueberry managers should recognize that encouraging more reproduction is not equivalent to encouraging better reproduction; no level of reproduction is consequence-free, and there may be practical limits beyond which greater reproductive effort is not physiologically sustainable for a plant. Elucidation of these limits moves us closer to a total understanding of plant ecology and evolution as well as to optimization of crop management techniques.

Download

Share