Growth of Cotton under Chronic Ozone Stress at Two Levels of Soil Moisture

摘要

Recent field research has shown that ambient concentrations of ozone(O3) have the potential to reduce yield of a number of economically important crop species. Less emphasis has been placed on characterization of the effects of O3 on growth of the total plant that ultimately determines yield. In the study, the authors measured season-long growth of field-grown cotton that was exposed to a range of O3 concentrations at two levels of soil moisture, well-watered (WW) and water-stressed (WS). The cotton was exposed for 12 h/d throughout the growing season in open-top chambers to five O3 concentrations. Three cotton plants were sampled from each chamber at 2-to 3-wk intervals during the season, and biomass and growth measurements were made on all major plant parts. Ozone stress reduced leaf and root biomass in particular, while stem tissues were less affected. Water stress caused fewer significant effects overall than did O3, although it appeared to reduce the growth of most plant parts, especially at low O3 concentrations.