Response of White Clover to Ozone in Different Environments
- Allen S. Heagle *,
- Richard A. Reinert and
- Joseph E. Miller
The value of research on effects of O3 done in greenhouse or field exposure systems is often questioned because chamber environments may affect plant response. Foliar injury, chlorophyll, and forage weight responses of two clones of white clover (Trifolium repens L.) to ambient O3 were compared for plants grown in charcoal-filtered (CF) and nonfiltered air (NF) in greenhouse and open-top field chambers and in ambient air (AA) plots at Raleigh, NC. One clone is sensitive to O3 (NC-S), whereas the other is resistant (NC-R). Comparisons of individual clone responses in CF vs. NF treatments in the greenhouse and in the field and the proportional response of the clones (defined as the NC-S/NC-R response ratio) were used to indicate the relative response to O3 in the different environments. Foliar injury and chlorophyll responses of NC-S to O3 were similar in the NF greenhouse, NF open-top chambers, and in AA. However, for individual harvests, the percentage decrease in NC-S forage weight in NF compared with CF was 7 to 23% greater in the greenhouse than in open-top chambers. The NC-S/NC-R forage ratios indicated that clover response to O3 in NF open-top field chambers was the same as in AA. Large environmental differences between greenhouse and open-top chambers apparently caused differences in plant responses to O3, whereas relatively small environmental differences between open-top chambers and ambient air did not.
Copyright © . .