Photosynthesis Research

, Volume 24, Issue 1, pp 27–34

A vapor pressure deficit effect on crop canopy photosynthesis

  • W. T. Pettigrew
  • J. D. Hesketh
  • D. B. Peters
  • J. T. Woolley
Regular Paper

DOI: 10.1007/BF00032641

Cite this article as:
Pettigrew, W.T., Hesketh, J.D., Peters, D.B. et al. Photosynth Res (1990) 24: 27. doi:10.1007/BF00032641


Canopy CO2-exchange rates (CER), air temperatures, and dew points were measured throughout ten days during the 1987 growing season for cotton (Gossypium hirsutum L.), grain sorghum [Sorghum bicolor (L) Moench], and five soybean [Glycine max (L) Merr.] cultivars, and throughout seven days in 1988, on maize (Zea maize L.). The objective was to determine if the decline in CER per unit light during the afternoon is associated with a vapor pressure deficit (VPD) increase. Some of the soybean and maize plots were kept as dry as possible. A VPD term significantly contributed (P≤0.05) to a canopy CER regression model in 54 of 80 data sets in 1987. Grain sorghum was less sensitive than the well-watered soybean genotypes to an increasing VPD (P≤0.05) on three of the ten measurement days and less sensitive than cotton (P≤0.05) on only one day. Cotton demonstrated less VPD sensitivity than soybean (P≤0.05) on one day. The moisture stressed soybean plots showed a greater CER sensitivity to VPD (P≤0.05) than the well-watered soybean plots. In 1988, the frequently irrigated maize plots were less sensitive to VPD (P≤0.05) than the rain-fed plots early in the season, before the rain-fed plots were excessively damaged by moisture stress. These results indicate that the afternoon declines in canopy CER found in a number of different species are associated with increases in the VPD; recent work of others suggests that this may be due to partial stomatal closure.

Key words

CO2-exchange rate Glycine max Gossypium hirsutum humidity hysteresis moisture stress Sorghum bicolor and Zea maize 



carbon dioxide exchange rate


vapor pressure deficit


photosynthetic photon flux density


days after planning

Copyright information

© Kluwer Academic Publishers 1990

Authors and Affiliations

  • W. T. Pettigrew
    • 1
  • J. D. Hesketh
    • 2
  • D. B. Peters
    • 2
  • J. T. Woolley
    • 2
  1. 1.USDA-ARSStonevilleU.S.A.
  2. 2.USDA-ARSUniv. of IllinoisUrbanaUSA

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