Orientation and Distribution of Leaves Within Soybean Canopies
1972
Blad, Blaine L. | Baker, Donald G.
‘Chippewa 64’ and ‘Hark’ soybean [Glycine max (L.) Merr.] varieties were studied at Lamberton and St. Paul, Minn. The average leaf sizes, numbers, and total leaf area index were determined during the growing season. The distribution of leaf area with height was obtained in the field and in a controlled environment chamber. The chamber-grown plants exhibited a distribution similar to the area distribution of a cylindrical cross-section. The field-grown soybeans had most of the leaf area near the upper portions of the plant canopy and did not have a cylindrical distribution. These variations in leaf area distributions are largely explained by differences in the light intensities at the lower canopy levels with the different growing conditions. Measurements of the azimuth directions of the soybean leaflets revealed that soybean leaves do not show any preferred direction. Leaf inclination distributions showed that soybean canopies were planophile through most of the growing season, except in the early and lategrowth stages, when the leaves were almost evenly distributed among all inclination classes. The Hark variety had smaller and slightly more vertically oriented leaves than the Chippewa 64 variety, which would allow greater penetration of light to the lower canopy levels.
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