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Crop Science Abstract -

Characterization of Canopy Photosynthesis of Chlorophyll-Deficient Soybean Isolines


This article in CS

  1. Vol. 29 No. 4, p. 1025-1029
    Received: July 21, 1988

    * Corresponding author(s):
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  1. W. T. Pettigrew ,
  2. J. D. Hesketh,
  3. D. B. Peters and
  4. J. T. Woolley
  1. Dep. of Agronomy and USDA-ARS, 1102 S. Goodwin Ave., Univ. of Illinois, Urbana IL 61801



The chlorophyll-deficient, near-isogenic lines of the soybean [Glycine max (L.) Merr.j genotype ‘Clark’, Clark y9 and Clark y11, have similar photosynthetic CO2-exchange rates (CER) per unit leaf area as the wild-type at full sun photosynthetic photon flux densities (PPFD). We hypothesized that, because of increased leaf reflectance and transmittance in such lines, more PPFD may penetrate the canopy, causing an increase in canopy CER. A 2-yr field study on a Flanagan silt loam (Aquic Argiudoll) was undertaken to compare canopy CERs of the chlorophyll-deficient isolines and the normal pigmented wild-type. Canopy CER measurements were taken throughout the majority of the daylight period for several days in both growing seasons. For an 11-d period in 1986, average CER values for Clark y9 were 14% higher than for Clark and during early pod fill average CER values for Clark y11 were 28% higher than for Clark in 1987. The canopy extinction coefficients for Clark y9 and Clark were not found to differ significantly. Clark and Clark y, were similar in maturity, but Clark y11 was on average 9 d earlier, which could have been a factor contributing to its higher CER. These results indicate that chlorophyll-deficient isolines can, at times, photosynthetically out-perform the wild-type, possibly because of increased PPFD penetration into the canopy.

Contribution of the Illinois Agric. Exp. Stn. and USDA-ARS.

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Copyright © 1989. Crop Science Society of America, Inc.Copyright © 1989 by the Crop Science Society of America, Inc.