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There is more information on the genetics of corn, than there is for any other economic plant or animal. Corn is well suited for this type of research, because it is grown easily, and can adapt to many different types of environments, with different conditions. It has a great number of distinct hereditary variations. Crossing, also known as inbreeding, is rapid and easy. Hundreds of kernels can come on a single ear from a single pollination. The mutation rates for the specific genes are measurable, and have a rather small amount of large chromosomes in the germ cell.
Since the '20's, a method of breeding hybrid corn came about, in which crossbreedoing between inbred lines was used. Usually, corn is cross-pollinated (where pollen is taken from one plant to another bye either wind or insects. This inbred corn fertilizes itself. Pollen from its tassel fertilizes the silks. The silks are protected from chance pollinated by other plants. Inbreeding is often continued through several generations, using only those progency that have good characteristics. When hybrids, also known as cross-strains, are produces by cross-breeding different types of inbred corn, complex techniques are usually involved. Since the '30's, the breeding and cultivation of hybrid corn results have been great.
Corn, and other monotyledon grains (i.e. rice, wheat), are less amenable to the stadard genetic engineering thechniques than the broad-leaved dicotyledons (i.e. tobacco, tomatoes). Science has successfully introduced a foreign gene into corn for the first time in 1988, and researchers think that is will make way for improvements in the variety of corn and other such cereals.
A perennial variety of teosinte, a wild grass related to corn, was discovered in the mountains in Jalisco, Mexico. These Zea diploperennis carry only 20 chromosomes, just like corn. Hoped by scientist, when the plants are croosbed, the new hybrid will grow perennially, and will be able to handle moist to wet soils.
The number of acres of corn hybrids in the US has gone up from under .1 percent in 1931, to almost 100 percent today. Grain yields went up almost 6,000 kilograms per hectacre from 1931 to 1985, and reached 7,408 kilograms per hectacre in 1985.