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Soybean Canopy Growth, Photosynthesis, and Transpiration Responses to Whole‐Season Carbon Dioxide Enrichment 1
Author(s) -
Jones Pierce,
Allen L. H.,
Jones J. W.,
Boote K. J.,
Campbell W. J.
Publication year - 1984
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1984.00021962007600040030x
Subject(s) - transpiration , canopy , carbon dioxide , photosynthesis , leaf area index , stomatal conductance , chemistry , water use efficiency , environmental science , photosynthetically active radiation , horticulture , zoology , agronomy , botany , biology , biochemistry , organic chemistry
Soybeans [ Glycine max (L.) Merr. cv. Bragg] were grown throughout their life cycle in six controlled‐environment chambers that maintained CO 2 concentrations at 330,450,600, and 800 µmol CO 2 mol −1 air. Air temperatures were controlled, and solar radiation and dewpoint temperatures were measured continually for each chamber. Net photosynthesis and transpiration were computed on 5‐min intervals. The CO 2 enrichment had no apparent effect on the rate of mainstem node development, but leaf area increased at a faster rate proportional to the CO 2 concentration. Daytime CO 2 exchange rate (CER) increased with increasing CO 2 and followed the same trend as final yield. Midday CER was typically about 90 µmol CO 2 m −1 of ground area s −1 for 800 µmol mol −1 and 60 µmol CO 2 m −2 ground area per second for 330 µmol mol −1 chambers. Canopy transpiration rates, leaf area index and vapor pressure deficits were used to compare bulk canopy resistances among CO 2 treatments. Bulk canopy resistance (stomatal and boundary‐layer) of the 800 µmol mol −1 treatment was about 1.6 times that of the 330 µmol mol −1 CO 2 treatment. These results imply that the expected continued increase in global atmospheric CO 2 will increase both agricultural productivity and water use efficiency.