SOYBEAN and BEES

Embryo, endosperm and seed coat development
After fertilization, the soybean plant becomes far more susceptible to insect pests, especially
those feeding on pods and seeds. Once fertilized, the vacuole in the zygote becomes smaller
and finally disappears entirely about the time of the first cell division, which occurs about 30
hours after pollination (Pamplin, 1963; Rustamova, 1964).
Soueges (1949) described soybean embryogeny from the first division of the zygote through
the early cotyledon stages. The first division of the zygote is transverse. The apical cell, facing
the central cell, will become the embryo. The basal cell, facing the micropyle, forms the
suspensor, an ephemeral structure that may aid early embryo growth. Continued divisions
of the derivatives of the apical cell produce the spherical proembryo, at about 3 days. The
proembryo is approximately the same size as the somewhat conical suspensor (LINSKENS et
al., 1977). A well-defined protoderm is present in the proembryo ca. 5 days after fertilization
(Figure 21).
Illustration: Decio Luiz Gazzoni
Shoot apical meristem
Protoderm
Endosderm
Hypocotyl
Procambium
Ground meristem
Seed coat
Cotyledons
Root apical meristem
Basal cell of suspensor
Figure 21. Development of the embryo, seed and endosperm.
About 6 to 7 days after fertilization, localized divisions at opposite sides of the proembryo,
just below the protoderm, initiate the cotyledons. Pamplin (1963) observed that the cotyle-
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