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This article in AJ

  1. Vol. 82 No. 3, p. 641-643
     
    Published: May, 1990


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doi:10.2134/agronj1990.00021962008200030040x

Respiration Measurements of Maize Plants Using a Whole-Plant Enclosure System

  1. R. G. Berard  and
  2. G. W. Thurtell
  1. A gric. Canada Res. Stn., Summerland, BC, Canada, VOH 1ZO
    T hurtell, Land Resource Science Dep., Univ. of Guelph, Guelph, Ontario, Canada, NIG 2WI

Abstract

Abstract

Field-portable enclosure systems are useful in assessing the impact of environmental parameters on crop growth rates and yields. These systems are normally designed to measure only one aspect of the C exchange budget, either the incoming (net photosynthesis) or outgoing (respiration) C fluxes. The objective of this work was to enable a whole-plant enclosure system, originally designed exclusively for field measurements of photosynthesis and transpiration, to be used additionally for respiration measurements. The conversion from photosynthesis to respiration measurement was relatively simple and required minimal modifications to the existing system. The technique basically involved substituting CO2-free air for CO2 as the gas being injected into the chamber to maintain a constant [CO2] within the chamber. Precise monitoring of air flow rate into the chamber allowed calculation of the whole-plant respiration rate. Calibration tests indicated that the system was accurate to within 5% of typical respiration rates. Nighttime measurements on the whole maize (Zea mays L.) plants yielded respiration rates typical of those reported in the literature. The system could be left unattended throughout the night daring respiration measurements, and could be converted back to daytime photosynthesis measurements within a few minutes. The ability of the enclosure system to provide constant day/night monitoring of whole-plant C exchange makes it a valuable tool in the study of environmental factors affecting the above-ground carbon balance of maize plants.

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