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Main Title Effects of Open-Top Chambers on 'Valencia' Orange Trees.
Author Olszyk, D. M. ; Takemoto, B. K. ; Kats, G. ; Dawson, P. J. ; Morrison., C. L. ;
CORP Author Corvallis Environmental Research Lab., OR. ;California State Air Resources Board, El Monte, CA. ;California Univ., Riverside. Statewide Air Pollution Research Center.
Publisher c1992
Year Published 1992
Report Number EPA/600/J-92/170;
Stock Number PB92-180355
Additional Subjects Air pollution effects(Plants) ; Citrus trees ; Air quality ; Fruit crops ; Plant physiology ; Plant growth ; Biological effects ; Test chambers ; Photosynthesis ; Plant growth ; Dose-response relationships ; Exposure ; Leaves(Botany) ; Ozone ; Long term effects ; Reprints ; Citrus sinensis
Library Call Number Additional Info Location Last
NTIS  PB92-180355 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 10p
Young 'Valencia' orange trees (Citrus sinensis(L) Osbeck) were grown for four years in large open-top chambers with ambient (nonfiltered) air or in outside air to determine any effects of the chambers on the air pollutant susceptibility of the trees. Long-term ozone average concentrations (12 hours, growing season) were 8% lower, and cumulative ozone dose (hourly values >0.1 microL/L) was 29% lower in ambient chambers compared to outside air. Fruit yields were much higher (>39%) for ambient chamber trees than for outside trees over three harvests, due at least partly to less fruit drop during the growing season for ambient chamber trees. Ambient chamber trees were much larger than outside trees and produced over twice as much leaf material over four years of study. Leaves on ambient chamber trees were larger and less dense than on outside trees. Leaves on ambient chamber trees were under more stress than leaves on outside trees during summer months; with lower stomatal conductances (14% average) and transpiration rates (12%), and more negative leaf water pressure potentials (28%). In contrast, leaves on ambient chamber trees had higher net photosynthetic rates (13%) and higher leaf starch concentrations prior to tree flowering (31%), than leaves on outside trees. While these results indicated large long-term impacts on tree growth which must be considered when using open-top chambers, they did not indicate any net effect of chambers on the air pollutant susceptibility of trees which would limit the usefulness of chamber tree data for air quality impact assessment purposes.