GROWTH OF 5 FAMILIES OF PINUS-TAEDA L DURING 3 YEARS OF OZONE EXPOSURE

Loblolly pine (Pinus taeda L.) seedlings of five half‐sib families were grown for 3 yr in the field in open‐top chambers. The seedlings were fumigated during the growing seasons (approximately April‐October) with ozone at the following target levels: subambient (CF), ambient (AMB), and ambient+ 60 ppb (AMB +). At the end of the three growing seasons, no significant ozone effects on diameter, height or total biomass of the seedlings were detected, and no statistically significant ozone‐family interactions were detected. Analysis of growth trends suggest that drought during the second and third growing seasons may have interacted with the ozone treatments. The importance of long‐term studies under realistic field conditions is discussed. Copyright © 1990, Wiley Blackwell. All rights reserved