The Hybrid Corn Miracle, 1991

what is this corn that we see row after row mile upon mile so even so straight so abundant it's hybrid corn the result of years of painstaking breeding and testing a revolutionary product of science applied to agriculture a hundred years ago farming was a lot different at the turn of the century average national yields of corn had not improved much from the previous century fluctuations were due mainly to climate yields remained much as they had been before averaging only 23 to 28 bushels per acre during the mid 30s average yields dropped because of drought but in the 40s yields increased to more than ever before the reason hybrid seed was introduced as we moved into the 50s and beyond average yields were bolstered by the use of fertilizers and pesticides improved machinery more plants per acre timeliness of operations and better farm management the major factor in these increases however was the continued development of better hybrid varieties today virtually all the seed corn that farmers plant is hybrid seed with average national yields of over 100 bushels per acre four times what it had been only 50 years before how did farmers accomplish this they changed their way of getting seed before hybrids farmers used open pollinated seed that is the silks of the ear on any plant could be pollinated from any of hundreds of different plants in the field each sister kernel on an ear may have had a different male parent when the farmer selected the best looking ear to save for planting next year he was actually saving a variety of genetically different kernels when he planted them the next spring hoping to produce a uniform crop of high-yield he got only a diverse non-uniform crop of average yield not much different from what he had in previous years hybrid seed however is not produced by the farmer it's scientifically developed by specialized seed corn companies which then sell their seed to farmers because of nearly identical heredity the hybrid plants have uniform resistance to pests and diseases for example they are adapted to the areas where they're grown and because of their uniformity they can be easily planted and harvested by machine so the higher price of the hybrid seed is offset by its dependably higher yields how then is a hybrid seed developed the process occurs in three steps the first is to produce genetically pure lines of seed by selective inbreeding an important characteristic of corn is that it has both male and female parts on the same plant the male part is the tassel which produces pollen the female part is made up of potential kernels on the ear shoot deep within the husk each potential kernel has an exposed silk attached to it to catch the pollen making reproduction possible inbreeding is the carefully controlled method of pollinating a plant with its own pollen the ear shoots are covered to prevent their silks from accidental pollination from neighboring plants each selected plant is carefully pollinated by hand this inbreeding and selecting process may be repeated for as many as six or seven generations until the plants heredity becomes uniform that is all plants of an inbred variety will look the same and will respond in a similar way to the environment hundreds of inbreds are produced and their resulting seeds are tested for the desired combination of traits what are some of these traits good seed must have traits adapted to the environmental conditions in which it is planted for example the soil type the amount and distribution of rainfall the length of the growing season and the prevalence of particular pests one such test is for resistance to the European corn borer an insect that's been a major threat to corn growers after they're infested the test inbreds are each evaluated to see which has done the best job of resisting these hungry insects by the time inbred testing is complete most will have failed to measure up and will have been discarded those inbreds showing the most desirable traits will go on to the second step of hybrid seed development experimental or test crossing the key to hybridizing is taking the pollen from one selected inbred and cross pollinating it with a second unrelated inbred the outcome is usually amazing the resulting hybrid seed produces a plant the following year that's bigger and stronger than either of its parents this is the miracle of hybrid vigor the purpose of this test Crossing is to find the cross of two inbreds that combines the desired traits and gives a higher yield than existing hybrids again the same carefully controlled methods of pollination are followed only this time the pollen from one inbred is crossed on to the silks of the other inbred thousands of inbreds are crossed the resulting hybrid seeds taken from the female plan are planted the following year for testing and evaluation this is time-consuming and expensive but it eventually comes up with a winning cross it's estimated that out of more than a thousand tests crosses only one will produce a hybrid seed that will perform significantly better than had existed before when the breeder has found a cross of two inbreds that produces an acceptable high yielding hybrid seed the third step begins mass producing it in sufficient quantities for sale to farmers seed corn companies contract with skilled farmers to do this on a large scale with the assistance of the company the two selected inbreds are planted in the same field in alternating sets of rows for example one male row of one inbred may be planted next to as many as four female rows of the other inbred and it is these female plants that will eventually produce the needed quantities of hybrid seed on these female seed rows the tassels are removed to prevent any accidental inbreeding detasseling machines often remove the majority of the tassels however it will take repeated trips through the field to remove all the tassels by hand because not all tassels emerge on the same day hand detasseling provides brief summer employment to many thousands of youngsters and migrant workers each year pollination occurs when the wind blows pollen from the male rose to the silks of the detasseled female rose the resulting hybrid seed is harvested from the female rose this is the seed that will be sold and distributed to farmers for planting next year but if looks could sell corn as it did a hundred years ago this corn would not be saleable yet these seeds have in them the tested hybrid vigor that will produce an abundant crop for the farmers who plant them before distribution the seed is taken to a conditioning plant where it's sorted dried sized and bagged for sale to farmers all over the world the farming of corn in the early 1900's was vastly improved by the introduction of hybridization today yields are at least four times that of the 1920s allowing farmers to export more corn to world markets enough to make a significant impact in helping feed the world this is the miracle of hybrid corn