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Influence of Elevated CO 2 on Growth of Soybean Plants 1
Author(s) -
Rogers Hugo H.,
Cure Jennifer D.,
Thomas Judith F.,
Smith Joy M.
Publication year - 1984
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1984.0011183x002400020036x
Subject(s) - relative growth rate , biology , zoology , dry matter , horticulture , leaf area index , dry weight , sowing , specific leaf area , growth rate , elongation , vegetative reproduction , botany , photosynthesis , mathematics , geometry , materials science , ultimate tensile strength , metallurgy
Continuing use of fossil fuels in industrialized countries has created a need to understand growth responses of major crop species to elevated concentrations of CO 2 . An analysis was therefore undertaken of the growth of soybeans [ Glycine max (L.) Merr. ‘Bragg’] grown in pots in open top field chambers at six CO 2 concentrations ranging from 332 μL L ‐1 (ambient) to 910 μL L ‐1 . Major growth response occurred with the first increments of added CO 2 with a maximum 66% increase in total vegetative dry matter at the 910 μL L ‐1 CO 2 level. Dry weight increases were proportionate among vegetative plant parts, although the harvest index was found to decrease slightly. Greater absolute growth rates in elevated CO 2 treatments were associated with greater rates of branch and internode elongation, leaf initiation, and leaf expansion. Yield increases represented greater seed numbers per plant rather than larger seeds. Percentage protein of seed decreased with CO 2 enrichment. In the interval from day 5 to 2 weeks after planting, mean relative growth rate (RGR) increased asymptotically with CO 2 concentration. Of the two components of RGR, the mean net assimilation rate (NAR) increased dramatically and mean leaf area ratio (LAR) decreased. In the intervals from week 2 to 7 and from week 7 to 12, RGR became constant across CO 2 treatments as the positive response of NAR and the negative response of LAR became less pronounced. Both RGR and NAR fell through the vegetative growth phase at each CO 2 level. The adjustment in LAR resulted from a decrease in specific leaf area while leaf weight ratio remained unaffected by CO 2 .