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Plant Physiology 75:187-191 (1984) © 1984 American Society of Plant Biologists Source/Sink Relations of Abscising and Nonabscising Soybean Flowers 1Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, Minnesota 55108
The partitioning of recently fixed 14C to setting and abscising flowers within the axillary raceme of `Clark' isoline E1t soybeans (Glycine max L. Merr) was examined as a function of time after anthesis of individual flowers. In such racemes, the first four flowers showed a 17% abscission while the next four flowers showed 47% abscission. Source/sink relations of flowers I-IV (normally setting) were compared to those of flowers V-VIII (normally abscising) by pulse labeling source leaves with 14CO2 and determining the radioactivity of individual flowers after a 4-hour chase period. The relative specific activity (RSA;% disintegrations per minute per% dry weight), sink strength (% disintegrations per minute), and its components, sink size (milligrams dry weight) and sink intensity (% disintegrations per milligram dry weight) were then calculated as a function of days after anthesis. Sink intensity (i.e. the competitive ability to accumulate photoassimilate per unit mass) was very high prior to anthesis of both setting and abscising flowers. Sink intensity then became very low for the first 3 days following anthesis after which it recovered in normally setting flowers, but failed to recover in normally abscising flowers. It is concluded that soybean reproductive abscission is determined at or very near the day of anthesis.
1 Supported in part by the United States Department of Agriculture under Grant 59-2271-0-2-020-0 from the Competitive Research Grants Office. Also supported in part by a grant from the Minnesota Soybean Research and Promotion Council. Contribution from the University of Minnesota Agricultural Experiment Station, St. Paul, MN 55108. Paper no. 13666, Scientific Journal Series. This article has been cited by other articles:
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