Influence of atmospheric vapour pressure deficit on ozone responses of snap bean (Phaseolus vulgaris L.) genotypes

Edwin L. Fiscus, Fitzgerald L. Booker, Walid Sadok, Kent O. Burkey

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10 Scopus citations

Abstract

Environmental conditions influence plant responses to ozone (O 3), but few studies have evaluated individual factors directly. In this study, the effect of O3 at high and low atmospheric vapour pressure deficit (VPD) was evaluated in two genotypes of snap bean (Phaseolus vulgaris L.) (R123 and S156) used as O3 bioindicator plants. Plants were grown in outdoor controlled-environment chambers in charcoal-filtered air containing 0 or 60 nl l-1 O3 (12 h average) at two VPDs (1.26 and 1.96 kPa) and sampled for biomass, leaf area, daily water loss, and seed yield. VPD clearly influenced O3 effects. At low VPD, O 3 reduced biomass, leaf area, and seed yield substantially in both genotypes, while at high VPD, O3 had no significant effect on these components. In clean air, high VPD reduced biomass and yield by similar fractions in both genotypes compared with low VPD. Data suggest that a stomatal response to VPD per se may be lacking in both genotypes and it is hypothesized that the high VPD resulted in unsustainable transpiration and water deficits that resulted in reduced growth and yield. High VPD-and water-stress-induced stomatal responses may have reduced the O3 flux into the leaves, which contributed to a higher yield compared to the low VPD treatment in both genotypes. At low VPD, transpiration increased in the O3 treatment relative to the clean air treatment, suggesting that whole-plant conductance was increased by O3 exposure. Ozone-related biomass reductions at low VPD were proportionally higher in S156 than in R123, indicating that differential O3 sensitivity of these bioindicator plants remained evident when environmental conditions were conducive for O3 effects. Assessments of potential O3 impacts on vegetation should incorporate interacting factors such as VPD.

Original languageEnglish (US)
Pages (from-to)2557-2564
Number of pages8
JournalJournal of experimental botany
Volume63
Issue number7
DOIs
StatePublished - Apr 2012

Keywords

  • Air pollutants
  • bioindicator
  • ozone
  • snap bean
  • transpiration
  • vapour pressure deficit

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