← Back to Search
Breeding, Genetics, And Seed Corn Production.
Published 2003 · Biology
Abstract Regular corn cells have nuclei with 20 chromosomes. Ten of these are derived from the egg cell and ten from the sperm nucleus that fertilizes the egg. Corn cross-pollinates when silks protruding from the ear shoot capture pollen grains from the tassel which germinate on the silk and then releases two sperms, each bearing 10 chromosomes. The nucleus of one sperm fuses with the egg to form the zygote (2n = 20 chromosomes), whereas the other with one of the two polar nuclei, which then fuses with the other polar nucleus, forms a primary endosperm nucleus with 3n cells. The corn kernel is a single fruit constituted by the embryo, endosperm, aleurone, and pericarp. The pericarp is the transformed ovary wall, whereas the single-layered aleurone is part of the endosperm containing 3n cells. The starchy endosperm makes up the greater part of the kernel and the embryo and is actually a dormant young corn plant constituted by the plumule and primary root and the scutellum rich in nutrients necessary for germination. The pedicel serves as the attachment point of the kernel to the cob. The main strategies used to generate new varieties and hybrids are mass selection, random selfed lines, recurrent selection, and single cross and modified single-cross hybridization. Corn kernels can be altered by genetic means to give modifications in quantity and type of starch, protein, oil, and other aspects such as pericarp thickness or kernel hardness. Because of these strategies, many specialty corns have been generated like white, waxy, high-amylose, quality protein, high oil, popcorn, and sweet corns. Certified or registered seed production requires special attention in order to keep the pedigree and assure viability. Seeds are carefully harvested, dried, shelled, cleaned/sized, and treated with pesticides before marketing.