Soybean and Bees

from genetic male sterile plants (msl,msl) in soybeans. Comparisons were made between
the average numbers of pollen grains and the average numbers of coenocytic microspores
with respect to environment where plants were grown, and to stamen position in
the flower. Pollen production from fertile plants varied from 374 to 760 pollen grains per
anther, among genetic lines and environments.
Photo: Decio Luiz Gazzoni
Figure 18. Open soybean flower: Detail of fused stamens involving the pistil, and the anthers covering the stigma,
with pollen grains capping the top of the structure.
The ovule of soybean has two integuments (bitegumic), and both ovule and embryo sac
are bent back on themselves (campylotropous). Megaspores form deep in the nucellus
(crassinucellate) (Prakash and Chan, 1976). As many as four ovules first appear as
small masses of tissue on the placenta, at alternate sides of the posterior suture of the
unicarpellate pistil.
The cells of an ovule primordium are all about the same size and covered by a single-layered
protoderm. Within 1 – 2 days after ovule initiation, several hypodermal archesporial cells
are distinguishable. These cells are larger than the neighboring ones and have more densely
staining cytoplasm. Soon, one of the archesporial cells surpasses the others in size and becomes
the functional megasporocyte. The neighboring cells of the archesporium become
50 SoybeAn and bees