Poster Session #44: Plant Ecology II.
Friday, August 10, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall


Plasticity of biomass allocation in response to multiple resource limitation.

Hire, Kelly1, McConnaughay, K.D.M.1, 1

ABSTRACT- A number of studies have shown that plants can alter biomass allocation patterns to increase acquisition of limited light or soil nutrients. We examined plant growth and biomass allocation responses under varied levels of light and nutrients simultaneously to determine whether plasticity in biomass allocation may be constrained when multiple resources are limited. Abutilon theophrasti seedlings were grown for 53 days (the entire vegetative growth phase) in each of 9 treatments (low, medium, and high availability for each of the two resources, fully-crossed to create 9 separate treatments). Plants grown under low light availability had lower growth rates and increased allocation to shoot biomass and the production of leaf area, consistent with optimal partitioning theories, regardless of nutrient availability. Plants grown under low-light and high-nutrient conditions exhibited high mortality rates, possibly due to nitrate toxicity. Plants grown under high-nutrient conditions allocated more biomass to leaf area production than their lower-nutrient-grown counterparts, possibly in response to an increased need for nitrate reductase capacity, but this was only shown for those plants grown in non-limiting light conditions. These results are partially consistent with predictions based on optimal partitioning theory, but suggest that biomass allocation responses of real-world plants faced with multiple resource limitation may not be easily predictable.

KEY WORDS: Abutilon theophrasti, resource availability, growth, biomass allocation