Detasseling corn is removing the pollen-producing flowers, the tassel, from the tops of corn (maize) plants and placing them on the ground. It is a form of pollination control, [1] employed to cross-breed, or hybridize, two varieties of corn.
Fields of corn that will be detasseled are planted with two varieties of corn. Removing the tassels from all the plants of one variety leaves the grain that is growing on those plants to be fertilized by the tassels of the other, resulting in a hybrid. In addition to being more physically uniform, hybrid corn produces dramatically higher yields than corn produced by open pollination. With modern seed corn, the varieties to hybridize are carefully selected so that the new variety will exhibit specific traits found in the parent plants. The detasseling process usually involves the use of both specialized machines and human labor.
Nearly all detasseling is done in two steps; the field is first detasseled by machine and then detasseled manually. Machine detasseling itself is typically a two step process. Initially a detasseling machine called a "cutter" goes through the rows of corn to be detasseled and cuts off the top portion of the plant. This is done to make the field more uniform so that a "puller" machine can come through the corn field a few days later and pull the tassel out of the plant by catching it between two rollers moving at a high speed. This removes the majority of the tassels.
Detasseling machines typically remove 60 to 90 percent of the tassels in a seed corn field. This is far less than the 99.5 percent that need to be removed to produce the uniformity of seed desired by farmers. The main problems for the machines are that they are unable to adapt quickly to height differences in plants and they throw tassels into the air where they can become lodged in other corn plants and inadvertently allow pollination. It is desirable that the pulled tassel ends up on the ground to prevent this problem.
Whether or not a field of seed corn is initially detasseled by machines, eventually people are employed to detassel the plants that the machines missed and to remove any tassels that the machines left in the leaves of other corn plants. This is done either by having "detasselers" walk through the corn field removing the tassels or by having detasselers ride through the corn field on a detasseler carrier. Detasseler carriers are typically employed when the corn is too tall to be detasseled from ground level. Each carrier can hold from eight to twelve detasselers.
Detasseling work is usually performed by teens; as such, it serves as a typical rite of passage in rural areas of the Corn Belt of the Midwestern United States. [2] [3] For many teens in these areas, it is their first job. Exact starting dates depend on the specific area of the country and the growing conditions of any given year. The detasseling "season" typically lasts from two to four weeks, with work days varying from just a few hours to over 10 hours, depending on the growing season. Wages for detasselers vary greatly; some detasselers earn minimum wage, while others earn over $12.00 per hour. Individual wages depend on the seed corn company, the detasseling contractor, the experience of the detasseler and even the individual field conditions, such as the number of plants per acre, percentage of the tassels pulled by a detasseling machine or the height of the corn.
The manner by which wages are determined can also vary greatly between detasseling contractors. Some pay a straight hourly wage; others pay on a piece rates basis, where detasselers are paid an amount for every row, panel or acre detasseled. Other contractors use a rating system to determine detasseler wages for a given day.
In addition to employing a large teenage workforce, some areas of the country employ migrant workers as detasselers. Migrant workers wages are usually paid on a piece rates basis.
Detasseling was used in the late 19th and early 20th centuries in the "ear-row" method of corn breeding. In this method, alternating rows of corn are detasseled and the seed from the detasseled rows is saved for planting the following season. However, ear-row breeding did not result in large yield increases and was largely abandoned after a few years. [4]
Around 1910, experimental corn breeders became excited by the possibility of improving corn yields by crossing two high yielding varieties. Again, this was accomplished by planting the varieties in alternating rows and detasseling one of the varieties. This method of seed production also proved disappointing and was also abandoned. [5]
However, the modern hybridization process, where one inbred line of corn is crossed with another, developed from this early work in cross breeding. In 1908, George Harrison Shull described heterosis, also known as hybrid vigor. Heterosis describes the tendency of the progeny of a specific cross to outperform both parents. In 1917, a process was developed that would make this hybridization commercially viable. In 1933, less than 1% of the corn produced in the United States was produced from hybrid seed; by 1944, over 83% was. [6] This hybrid seed is produced by crossing two inbred lines by planting a row of one inbred variety followed by several rows of a second variety. The tassels of the second variety were removed by hand so that the second variety could be pollinated by the first.
Hybrid corn was detasseled manually until the mid-1950s, when a cytoplasm was discovered that would cause one of the inbred lines to be male sterile while the hybridized seed corn it produced would regain male fertility. This gene allowed seed corn companies to greatly reduce their labor costs by producing seed corn without the need for manual detasseling. By the mid-1960s, nearly all seed corn was produced with this gene. [7]
This situation changed in 1971 with an outbreak of the fungus southern corn leaf blight. The cytoplasm used to produce male sterility was highly susceptible to this fungus. At the time, approximately 90% of hybrid corn used in the United States contained this gene. [8] About 15% of the corn crop was lost to infection, and for the next few years, male sterility was abandoned and nearly all seed corn was again detasseled manually. [9]
In the mid-1970s, machines were developed to help reduce the large labor costs associated with manual detasseling and as a response to a shrinking rural teen labor force. In the 1980s, male sterile varieties that were not susceptible to southern corn leaf blight were reintroduced; however, the reliance on a single sterile variety seen in the 1960s has not been repeated. [10]
Today, corn hybridization is accomplished by a combination of machine and manual detasseling as well as male-sterile genes.
Seed corn fields are planted in a repetitive pattern known as a "panel", "block" or "set", depending on the area of the country. There are two main planting patterns for these panels. A panel may be planted in a 6:2 pattern, where six "female" rows, the rows to be detasseled, are followed by two "male" or "bull" rows, the rows that will be used to pollinate the detasseled rows. Panels are also commonly planted in a 4:1 ratio, with four female rows followed by a single male row. Other, less common, patterns are also used, including 4:2 and 4:1:6:1. In all cases, the pattern is continued throughout the corn field. [11]
All or portions of seed corn fields may be surrounded by extra rows of male plants if it is likely that wind may carry foreign pollen into the seed corn field. These extra rows are called "buffer" or "isolation" rows, depending on the area of the country. Another important aspect to keeping undesirable pollen out of seed corn fields is a process known as roguing, a process that removes plants that differ from the variety intentionally planted.
In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different varieties, subspecies, species or genera through sexual reproduction. Generally, it means that each cell has genetic material from two different organisms, whereas an individual where some cells are derived from a different organism is called a chimera. Hybrids are not always intermediates between their parents such as in blending inheritance, but can show hybrid vigor, sometimes growing larger or taller than either parent. The concept of a hybrid is interpreted differently in animal and plant breeding, where there is interest in the individual parentage. In genetics, attention is focused on the numbers of chromosomes. In taxonomy, a key question is how closely related the parent species are.
Heterosis, hybrid vigor, or outbreeding enhancement is the improved or increased function of any biological quality in a hybrid offspring. An offspring is heterotic if its traits are enhanced as a result of mixing the genetic contributions of its parents. The heterotic offspring often has traits that are more than the simple addition of the parents' traits, and can be explained by Mendelian or non-Mendelian inheritance. Typical heterotic/hybrid traits of interest in agriculture are higher yield, quicker maturity, stability, drought tolerance etc.
Yuan Longping was a Chinese agronomist and inventor. He was a member of the Chinese Academy of Engineering known for developing the first hybrid rice varieties in the 1970s, part of the Green Revolution in agriculture. For his contributions, Yuan is known as the "Father of Hybrid Rice".
F1 hybrid (also known as filial 1 hybrid) is the first filial generation of offspring of distinctly different parental types. F1 hybrids are used in genetics, and in selective breeding, where the term F1 crossbreed may be used. The term is sometimes written with a subscript, as F1 hybrid. Subsequent generations are called F2, F3, etc.
"Open pollination" and "open pollinated" refer to a variety of concepts in the context of the sexual reproduction of plants. Generally speaking, the term refers to plants pollinated naturally by birds, insects, wind, or human hands.
In agriculture and gardening, hybrid seed is produced by deliberately cross-pollinated plants which are genetically diverse. Hybrid seed is common in industrial agriculture and home gardening. It is one of the main contributors to the dramatic rise in agricultural output during the last half of the 20th century. Alternatives to hybridization include open pollination and clonal propagation.
Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Almost all gymnosperms are anemophilous, as are many plants in the order Poales, including grasses, sedges, and rushes. Other common anemophilous plants are oaks, pecans, pistachios, sweet chestnuts, alders and members of the family Juglandaceae. Approximately 12% of plants across the globe are pollinated by anemophily, including cereal crops like rice and corn and other prominent crop plants like wheat, rye, barley, and oats. In addition, many pines, spruces, and firs are wind-pollinated.
Hand pollination, also known as mechanical pollination is a technique that can be used to pollinate plants when natural or open pollination is either undesirable or insufficient.
A seedless fruit is a fruit developed to possess no mature seeds. Since eating seedless fruits is generally easier and more convenient, they are considered commercially valuable.
Cytoplasmic male sterility is total or partial male sterility in hermaphrodite organisms, as the result of specific nuclear and mitochondrial interactions. Male sterility is the failure to produce functional anthers, pollen, or male gametes. Such male sterility in hermaphrodite populations leads to gynodioecious populations.
Hybrid rice is a type of Asian rice that has been crossbred from two very different parent varieties. As with other types of hybrids, hybrid rice typically displays heterosis or "hybrid vigor", so when grown under the same conditions as comparable purebred rice varieties, it can produce up to 30% more yield. To produce hybrid seeds in large quantity, a purebred sterile rice variety is fertilized with fertile pollen from a different variety. High-yield crops, including hybrid rice, are one of the most important tools for combatting worldwide food crises.
The Connecticut Agricultural Experiment Station (CAES) is the Connecticut state government's agricultural experiment station, a state government component that engages in scientific research and public outreach in agriculture and related fields. It is the oldest state experiment station in the United States, having been founded in 1875. Its official mission is to "develop, advance, and disseminate scientific knowledge, improve agricultural productivity and environmental quality, protect plants, and enhance human health and well-being through research for the benefit of Connecticut residents and the nation." The station operates a main research campus in New Haven, a research farm in Hamden, a satellite research facility and farm in Windsor, and a research farm in Griswold. The Storrs Agricultural Experiment Station is a separate agricultural research agency, founded in 1887 and part of the University of Connecticut, which also receives state and federal funding.
Joseph Gottlieb Kölreuter, also spelled Koelreuter or Kohlreuter, was a German botanist who pioneered the study of plant fertilization, hybridization and was the first to detect self-incompatibility. He was an observer as well as a rigorous experimenter who used careful crossing experiments although he did not inquire into the nature of heritability.
Maize, also known as corn in North American English, is a tall stout grass that produces cereal grain. It was domesticated by indigenous peoples in southern Mexico about 9,000 years ago from wild teosinte. Native Americans planted it alongside beans and squashes in the Three Sisters polyculture. The leafy stalk of the plant gives rise to male inflorescences or tassels which produce pollen, and female inflorescences called ears. The ears yield grain, known as kernels or seeds. In modern commercial varieties, these are usually yellow or white; other varieties can be of many colors.
Dent corn, also known as grain corn, is a type of field corn with a high soft starch content. It received its name because of the small indentation, or "dent", at the crown of each kernel on a ripe ear of corn. Reid's Yellow Dent is a variety developed by central Illinois farmer James L. Reid. Reid and his father, Robert Reid, moved from Brown County, Ohio, to Tazewell County, Illinois, in 1846 bringing with them a red corn variety known as "Johnny Hopkins", and crossed it with varieties of flint corn and flour corn. Most of today's hybrid corn varieties and cultivars are derived from it. This variety won a prize at the 1893 World's Fair.
Plant breeding is the science of changing the traits of plants in order to produce desired characteristics. It has been used to improve the quality of nutrition in products for humans and animals. The goals of plant breeding are to produce crop varieties that boast unique and superior traits for a variety of applications. The most frequently addressed agricultural traits are those related to biotic and abiotic stress tolerance, grain or biomass yield, end-use quality characteristics such as taste or the concentrations of specific biological molecules and ease of processing.
Plant breeding started with sedentary agriculture, particularly the domestication of the first agricultural plants, a practice which is estimated to date back 9,000 to 11,000 years. Initially, early human farmers selected food plants with particular desirable characteristics and used these as a seed source for subsequent generations, resulting in an accumulation of characteristics over time. In time however, experiments began with deliberate hybridization, the science and understanding of which was greatly enhanced by the work of Gregor Mendel. Mendel's work ultimately led to the new science of genetics. Modern plant breeding is applied genetics, but its scientific basis is broader, covering molecular biology, cytology, systematics, physiology, pathology, entomology, chemistry, and statistics (biometrics). It has also developed its own technology. Plant breeding efforts are divided into a number of different historical landmarks.
Dhara Mustard Hybrid-11, otherwise known as DMH - 11, is a genetically modified hybrid variety of the mustard species Brassica juncea. It was developed by Professor Deepak Pental from the University of Delhi, with the aim of reducing India's demand for edible oil imports. DMH - 11 was created through transgenic technology, primarily involving the Bar, Barnase and Barstar gene system. The Barnase gene confers male sterility, while the Barstar gene restores DMH - 11's ability to produce fertile seeds. The insertion of the third gene Bar, enables DMH - 11 to produce phosphinothricin-N- acetyl-transferase, the enzyme responsible for Glufosinate resistance. This hybrid mustard variety has come under intense public scrutiny, mainly due to concerns regarding DMH - 11's potential to adversely affect the environment as well as consumer health. DMH - 11 was found not to pose any food allergy risks, and has demonstrated increased yields over existing mustard varieties. Conflicting details and results regarding the field trials and safety evaluations conducted on DMH - 11 have delayed its approval for commercial cropping.
Starmaya is an F1 hybrid coffee tree that can be propagated by seed rather than through somatic embryogenesis (SE). It was propagated from a parent plant that is male-sterile. This facilitates controlled pollination because breeders do not have to manually castrate each individual flower of the autogamous coffee tree.
Silphium integrifolium is a species of flowering plant in the family Asteraceae. Its common names include rosinweed, whole-leaf rosinweed, entire-leaf rosinweed, prairie rosinweed, and silflower. It is native to eastern North America, including Ontario in Canada and the eastern and central United States as far west as New Mexico.