Project at a Glance

Title: The effect of ozone on photosynthesis, vegetative growth and productivity of Prunus salicina in the San Joaquin Valley of California: final report on ARB contract A833-113 (Year One)

Principal Investigator / Author(s): Williams, Larry Edward

Contractor: University of California, Davis

Contract Number: A833-113

Research Program Area: Ecosystem & Multimedia Effects

Topic Areas: Agriculture, Ecosystem Impacts, Impacts


Nursery stock of plum (Prunus salicina cv. Casselman) were planted 1 April 1988 in an experimental orchard at the University of California Kearney Agricultural Center near Fresno, California. The trees were covered with open top fumigation chambers on 1 May 1989 and were exposed to three atmospheric ozone concentrations (charcoal filtered air, ambient air, or ambient air + ozone) from 8 May to 15 November 1989. A no-chamber treatment plot was utilized to assess chamber effects on tree performance. The mean 12-h (0800-2000 h PDT) ozone concentrations during the experimental period ozone in the charcoal filtered, ambient, ambient + ozone, and no-chamber treatments were 0.044, 0.059, 0.111, and 0.064 ppm, respectively. Leaf assimilation rate and stomatal conductance of Casselman plum were reduced by increased ozone concentrations. There was no difference in Casselman plum gas exchange between the ambient chamber and no-chamber plots. Trees in the high ozone treatment had greater leaf-fall earlier in the growing season than those of the other treatments. Cross sectional area growth of Casselman plum decreased with increasing atmospheric ozone concentration. The results indicate that decrease in leaf gas exchange and loss of leaf surface area were probable contributors to decreases in growth of young Casselman plum trees.

For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

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