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Equations for the Rate of Dark Respiration of White Clover and Grain Sorghum, as Functions of Dry Weight, Photosynthetic Rate, and Temperature 1
Author(s) -
McCree K. J.
Publication year - 1974
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/cropsci1974.0011183x001400040005x
Subject(s) - sorghum , photosynthesis , respiration , zoology , respiration rate , biology , trifolium repens , dry weight , botany , q10 , horticulture , agronomy
Equations were designed to be used in computer models of photosynthesis and respiration in crops. They were developed from new experimental data on the rates CO 2 exchange of whole plants grown under constant conditions. The dark respiratory rate was separated into two components. The “maintenance” component was taken to be the efflux of CO 2 after more than 48 hours in the dark at constant temperature. This component was proportional to the dry weight of the plant (W), and was a strong function of temperature (T). The proportionality constant (c) was about twice as great for clover ( Trifolium repens L.) as it was for sorghum ( Sorghum bicolor L.), at the same temperature. The “growth” component was taken to be the difference between the “maintenance” component and the total efflux during a normal night period (N). This component was proportional to the total influx during the previous daytime period (D), and the proportionality constant (k) was independent of species and temperature. The values of c and k were in good agreement with values calculated by Penning de Vries, using the principles and equations of biochemistry. The experimental data were best fitted by the following equations: For clover at 30C: N = 0.14 D + 0.0143W For sorghum at 30C: N = 0.14 D + 0.0054WTemperature dependence of maintenance coefficient: c T = c 30 (0.044 + 0.0019 T + 0.0010 T 2 ) where N = night total of CO 2 evolved in g•12h ‐l •plant ‐1 , D = daytime total of CO 2 taken up in g•12h ‐1 •plant ‐1 , W = CO 3 equivalent of dry weight in g•12h ‐1 •plant ‐1 , T = temperature in °C.