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Characterization of Canopy Photosynthesis of Chlorophyll‐Deficient Soybean Isolines
Author(s) -
Pettigrew W. T.,
Hesketh J. D.,
Peters D. B.,
Woolley J. T.
Publication year - 1989
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/cropsci1989.0011183x002900040040x
Subject(s) - canopy , biology , photosynthesis , chlorophyll , botany , chlorophyll a , photosynthetically active radiation , horticulture , loam , agronomy , ecology , soil water
The chlorophyll‐deficient, near‐isogenic lines of the soybean [ Glycine max (L.) Merr.j genotype ‘Clark’, Clark y 9 and Clark y 11 , have similar photosynthetic CO 2 ‐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 y 11 were 28% higher than for Clark in 1987. The canopy extinction coefficients for Clark y 9 and Clark were not found to differ significantly. Clark and Clark y, were similar in maturity, but Clark y 11 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.