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What's in a Soybean Seed?
seed anatomy (information provided by The Ohio State University; ©Copyright
by M.Teplitski and P.McMahon, 1999).
Seed of a fava bean on the left is a true
seed, covered by testa(1), the seed coat. The legume seeds are attached to
the pod (legume fruit) by hilum(2), through
which the seeds receive food during their growth and development. Hila may vary
in color, thus providing means for identification. The embryo area is an area
of the embryo axis which develops into the seedling and is in a very vulnerable
position for mechanical damage.
An embryo consists of:
- an epicotyl (5), embryonic shoot and
leaves. It contains the growing point and
the first two unifoliate leaves;
- hypocotyl (6), the stem tissue between the
epicotyl and radicle. In most legumes the hypocotyl elongates during germination
to cause emergence of the seedling;
- radicle (4), embryonic root found in
the lower portion of the embryo axis.
Energy for germination is stored in the two cotyledons (3). Soybean cotyledons
contain ~20% oil and 40% protein. Nutrient and food reserves in the cotyledons
supply the needs of the young plant during emergence and for about 7-10 days
after emergence. Loss of one cotyledon has little effect on the young plantís
growth rate, but loss of both cotyledons soon after emergence will reduce yield
ARS – Soybean Genomics and Improvement Laboratory
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