Genetic background To understand the background of some cultivation methods it is inevitable to look at the special genetics of the genus corn.
In all corn forms, male and female flowers grow separate from each other on the same plant. The male flowers (delivering pollens) are situated in the panicle, whereas the female flowers develop in the leaf axillas on an ear, which has the shape of a cob. Thus, corn is a cross-pollinated plant with the wind transporting the pollens.
The ears contain large quantities of the female flowers, arranged in regular rows, which later form the kernels. From each of them arises a threadlike pistil with a length of up to 50 cm. These pistils are necessary for the pollination. The 300 – 900 pistils of all flowers on one ear form a “tassel”. At the time of pollination they stand out from the leaves which wrap the ear.
About 2 – 4 days before the pistils develop, the same plant produces pollens in large numbers (aprox. 4,5 millions/ panicle). This is a process which supports the cross-pollination, and thus, the pollination is generally caused by the pollens of another plant (aprox. 95%). Each pistil must be pollinated to achieve a regular arrangement of kernels on the ear.
Each pollen includes two cell nuclei with a complete set of the genetic information of the pollinating plant (haploid). After the pollination with the ovum, which contains a single set of maternal chromosomes, one of these nuclei forms the embryo, which then includes paternal and maternal genotypes.
The second nucleus of the pollen combines with the duplicate maternal chromosome set of the nutritive tissue (endosperm) to form the so-called triploid nucleus (threefold chromosome set), which contains a duplicate set of the maternal chromosomes and a single set of the paternal chromosomes.
The main part of the kernel consists of this triploid nutritive tissue, the characteristics of which are determined by the combination of the genetic information on the chromosomes (= genes).