PARENT SESSION
Organized Oral Session 1: Understanding the impacts of oxidative stress in plants: From molecules to ecosystems
Organizer(s): HS Neufeld and N Grulke
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 510a, Level 5, Palais des congrès de Montréal

The physiological ecology of ozone impacts on root development.

Grantz, David^*,1, ¹ University of California, Parlier, CA

ABSTRACT- Ozone impacts on plant development are variable. In many cases, allocation of current photosynthate to below ground sink tissues is reduced. This is associated with reductions in source strength due to inhibition of both photosynthesis and phloem loading. Sugar profiles in root sink tissue are altered in favor of raffinose and stachyose at the expense of sucrose. In isolated plants a major consequence of reduced allocation below ground is reduced plant hydraulic conductance. In plant communities competitive outcomes are altered. In irrigated and fertilized agricultural systems altered competitive outcomes may be independent of hydraulic factors but dependent on other aspects of competition. Competition between yellow nutsedge and cotton or tomato takes place largely below ground. Outcomes differ between the two systems as a function of increasing ozone. Tomato is increasingly resistant to the ozone x weed challenge, but cotton is increasingly sensitive. Prediction of outcomes may depend on root responses to ozone which are difficult to quantify. Relative responses of root tip respiration and of root system morphology may prove useful in this regard.

Key words: ozone, roots, competition, phloem translocation