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OZONE DECREASES SPRING ROOT GROWTH AND ROOT CARBOHYDRATE CONTENT IN PONDEROSA PINE THE YEAR FOLLOWING EXPOSURE
Citation:
Andersen, C., W. Hogsett, R. Wessling, AND M. Plocher. OZONE DECREASES SPRING ROOT GROWTH AND ROOT CARBOHYDRATE CONTENT IN PONDEROSA PINE THE YEAR FOLLOWING EXPOSURE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-92/031 (NTIS PB92144039).
Description:
Storage carbohydrates are extremely important for new shoot and root development following dormancy or during periods of high stress. he hypothesis that ozone decreases carbohydrate storage and decreases new root growth during the year following exposure was investigated. eedlings exposed to ozone in 1989 were harvested prior to shoot elongation(non-growing seedlings) and following a root growth test(growing seedlings) in the spring of 1990 to evaluate starch and soluble sugar concentrations. Seedlings exposed to the highest ozone level had 34% less lateral root biomass and 5% less new root biomass the following spring. xposure to 122 and 169 ppm hrs (sum of hourly means, 24 hr/day, over the exposure period) during the 1989 growing season resulted in significant decreases of all carbohydrate pools examined in both nongrowing and growing seedlings the following spring. tarch concentrations were most affected, showing decreases of 43 and 44% in coarse and fine roots, respectively, of non-growing seedlings, and 50, 65 and 62% in coarse, fine and new roots, respectively, of growing seedlings at the highest ozone level. he results suggest that a) ponderosa pine seedlings exposed to 122 and 169 ppm hrs ozone for one season have significantly less root starch reserves available just prior to and during bud break the following year, and b) spring root growth is decreased following ozone exposure. The carry-over effects of ozone stress may be important in long-lived perennial pecies which are annually subjected to ozone.