Document: TOD-3-42-27

Long-term induction, soil nutrient availability and plant genotype: Quaking aspen growth, foliar chemistry and effects on a generalist herbivore.

OSIER, T.L.* and R.L.LINDROTH

University of Wisconsin, Madison, WI 53706 USA ¹

Abstract:
Genetic and environmental variability and their interactions are known to influence phytochemical composition and, in turn, herbivore performance. Further development of our theories of plant insect interactions requires improvement in our understanding of the relative roles of genetic and environmental factors. We used a common garden study to partition the effects of plant genotype and two environmental factors (soil nutrient availability and artificial defoliation) on plant growth and foliar chemistry of quaking aspen. We grew saplings of four aspen genotypes under two conditions of nutrient availability, and subsequently subjected these saplings to two levels of artificial foliar defoliation. In the year following defoliation, plant growth was influenced most by the nutrient availability treatment, however, plant genotype and artificial defoliation also played a role. Although all three experimental factors impacted plant growth, defoliation in the previous year did not affect phytochemistry in ways important for insect herbivores. The lack of a dramatic phytochemical response was surprising given the severity of the defoliation treatment (nearly 100% of leaf area was removed). Although the phytochemical response to the defoliation treatment was weak, the saplings did show evidence of tolerance. Plant tolerance to herbivory varied greatly and was dependent on both plant genotype and soil fertility conditions, however, relationships among tolerance and plant chemistry were not evident.

Keywords: plant-insect interactions, defoliation, soil fertility, plant genotype

This abstract is being presented at: 9:00 AM in session:
Oral Session #44: Terrestrial Invertebrates: Foodwebs and Plant Responses.