Science Fair Project Encyclopedia
- This article is about peanut, the plant. There is a separate article about Peanuts, the comic strip by Charles M. Schulz.
The Peanut (Arachis hypogaea) is a species in the pea family Fabaceae native to South America. It is an annual herbaceous plant growing to 30-50 cm tall. The leaves are alternate, pinnate with four leaflets (two opposite pairs; no terminal leaflet), each leaflet 1-7 cm long and 1-3 cm broad. The flowers are a typical peaflower in shape, 2-4 cm across, yellow with reddish veining. After pollination, the fruit develops into a legume 3-7 cm long containing 2-3 (rarely 1 or 4) seeds, which forces its way underground to mature. Although a nut in the culinary sense, in the botanical sense the fruit of the peanut is a woody, indehiscent legume or pod.
Peanuts are also known as Groundnuts (because they grow underground), Earthnuts, Goobers, Goober peas, Pindas, Pinders, Manila nuts and Monkey nuts (the last of these is often used to mean the entire pod, not just the seeds).
Archaeological evidence demonstrates that the peanut was domesticated in prehistoric times in South America, where wild ancestors are still found. The plant was later spread worldwide by European traders. Cultivation in North America was popularized by African American, who brought the Kikongo word goober.
The flower of the Arachis hypogaea is borne above ground and after it withers, the stalk elongates, bends down, and forces the ovary underground. When the seed is mature, the inner lining of the pods (called the seed coat) changes color from white to a reddish brown. The entire plant, including most of the roots, is removed from the soil during harvesting.
The pods begin in the orange veined, yellow petaled, pealike flowers, which are borne in axillary clusters above ground. Following self-pollination (peanuts are complete inbreeders), the flowers fade. The stalks at the bases of the ovaries, called pegs, elongate rapidly, and turn downward to bury the fruits several inches in the ground to complete their development.
The pods act in nutrient absorption. The fruits have wrinkled shells that are constricted between the two to three seeds. The mature seeds resemble other legume seeds, such as beans, but they have paper-thin seed coats, as opposed to the usual, hard legume seed coats.
Peanuts grow best in light, sandy loam soil. They require five months of warm weather, and an annual rainfall of 50-100 cm (20-40 inches) or the equivalent in irrigation water.
The pods ripen 120 to 150 days after the seeds are planted. If the crop is harvested too early, the pods will be unripe. If they are harvested late, the pods will snap off at the stalk, and will remain in the soil.
Cultivars of Peanuts
Thousands of peanut cultivars are grown, with four major Cultivar Groups being the most popular: Spanish, Runner, Virginia, and Valencia. There are also Tennessee Red and Tennessee White groups. Certain Cultivar Groups are preferred for particular uses because of differences in flavor, oil content, size, shape, and disease resistance. For many uses the different cultivars are interchangeable. Most peanuts marketed in the shell are of the Virginia type, along with some Valencias selected for large size and the attractive appearance of the shell. Spanish peanuts are used mostly for peanut candy, salted nuts, and peanut butter. Most Runners are used to make peanut butter.
The various types are distinguished by branching habit and branch length. There are numerous varieties of each type of peanut. There are two main growth forms, bunch and runner. Bunch types grow upright, while runner types grow near the ground.
Each year new cultivars of peanuts are bred and introduced somewhere in the peanut belt of the U.S. or in other countries. Introducing a new cultivar may mean change in the planting rate, adjusting the planter, harvester, dryer, cleaner, sheller, and method of marketing.
The small Spanish types are grown in South Africa, and in the southwestern and southeastern U.S. Prior to 1940, 90 percent of the peanuts grown in Georgia were Spanish types, but the trend since then has been larger seeded, higher yielding, more disease resistant cultivars. Spanish peanuts have a higher oil content than other types of peanuts and in the U.S. are now primarily grown in Oklahoma and Texas.
Cultivars of the Spanish group include 'Dixie Spanish', 'Improved Spanish 2B', 'GFA Spanish', 'Argentine', 'Spantex', 'Spanette', 'Shaffers Spanish', 'Natal Common (Spanish)', 'White Kernel Varieties', 'Starr', 'Comet', 'Florispan', 'Spanhoma', 'Spancross', and 'Wilco I'.
Since 1940, there has been a shift to production of Runner group peanuts in the southeastern U.S. Runners are found in Georgia, Alabama, Florida, and South Carolina. This shift is due to good flavor, better roasting characterics and higher yields when compared to Spanish types leading to food manufacturers' preference for use in peanut butter and salting.
Cultivars of Runners include 'Southeastern Runner 56-15', 'Dixie Runner', 'Early Runner', 'Virginia Bunch 67', 'Bradford Runner', 'Egyptian Giant' (also known as 'Virginia Bunch' and 'Giant'), 'Rhodesian Spanish Bunch' (Valencia and Virginia Bunch), 'North Carolina Runner 56-15', 'Florunner', and 'Shulamit'.
The large seeded Virginia Group peanuts are grown in Virginia, North Carolina, Tennessee, and parts of Georgia. They are increasing in popularity due to demand for large peanuts for processing, particularly for salting, confections, and roasting in the shells.
Virginia Group peanuts are either bunch or running in growth habit. The bunch type is upright to spreading. It attains a height of 45-55 cm (18-22 inches), and a spread of 70-80 cm (28-30 inches), with 80-90 cm (33-36 inch) rows that seldom cover the ground. The pods are borne within 5-10 cm of the base of the plant.
Cultivars of Virginia type peanuts include 'Virginia Bunch Large', 'Virginia Bunch 46-2', 'Virginia Bunch Small', 'Virginia Bunch 67', 'Virginia Bunch G2', 'Virginia Runner G26', 'NC 4X', 'NC 2', 'NC 5', 'Georgia Hybrid 119-20', 'Holland Jumbo', 'Holland Station Runner', 'Adkins Runner', 'Virginia Runner 26', 'Virginia Runner G' ('Holland Virginia Runner'), 'Virginia 56 R', 'Virginia 61 R', 'Florigiant', 'Georgia Hybrid 119-18', 'Virginia B22-15', 'Virginia A17-12', 'Virginia A23-7', and 'Florida 416'.
Valencia Group peanuts are coarse, and they have heavy reddish stems and large foliage. In the U.S. they are primarily grown in Eastern New Mexico. They are comparatively tall, having a height of 125 cm (50 inches) and a spread of 75 cm (30 inches). Peanut pods are borne on pegs arising from the main stem and the side branches. Most of the pods are clustered around the base of the plant, and only a few are found several inches away. Valencia types are three seeded and smooth, with no constriction between the seeds. Seeds are oval and tightly crowded into the pods. There are two strains, one with flesh and the other with red seeds. Typical seed weight is 0.4-0.5 g.
Tennessee Red and Tennessee White Groups
These are alike, except for the color of the seed. The plants are similar to Valencia types, except that the stems are green to greenish brown, and the pods are rough, irregular, and have a smaller proportion of kernels.
Peanuts for edible uses account for two-thirds of the total peanut consumption in the United States. The principal uses are salted, shelled nuts, peanut butter (popular in sandwiches), peanut brittle, candy bars, and nuts that have been roasted in the shell. Salted peanuts are usually roasted in oil and packed in retail size, plastic bags or hermetically sealed cans. Dry roasted, salted peanuts are also marketed in significant quantities. The primary use of peanut butter is in the home, but large quantities are also used in the commercial manufacture of sandwiches, candy, and bakery products. Boiled peanuts are a preparation of raw, unshelled green peanuts typically eaten as a snack in the southern United States where most peanuts are grown. Peanuts are also often eaten raw, or boiled in salt water. Peanut oil is often used in cooking, because it has a mild flavor and burns only at a relatively high temperature.
Peanuts are also very widely sold for garden bird feeding. Low grade or culled peanuts not suitable for the edible market are used in the production of peanut oil, seed and feed.
Peanuts have a variety of industrial end uses. Paint, varnish, lubricating oil, leather dressings, furniture polish, insecticides, and nitroglycerin are made from peanut oil. Soap is made from saponified oil, and many cosmetics contain peanut oil and its derivatives. The protein portion of the oil is used in the manufacture of some textile fibers.
Peanut shells are put to use in the manufacture of plastic, wallboard, abrasives, and fuel. They are also used to make cellulose (used in rayon and paper) and mucilage (glue).
Peanut plant tops are used to make hay. The protein cake (oilcake meal) residue from oil processing is utilized as an animal feed and as a soil fertilizer.
Although many people enjoy foods made with peanuts, some people have severe allergic reactions to peanuts. For people with peanut allergy, exposure can cause fatal anaphylactic shock. For these individuals, eating a single peanut or just breathing the dust from peanuts can cause a fatal reaction.
A theory of the development of peanut allergy has to do with the way that peanuts are processed in North America versus other countries like China. Peanuts are widely eaten in China but the prevalence of peanut allegry is almost unheard of there. Soheila J. Maleki, PhD, from the United States Department of Agriculture discovered that roasting peanuts as is done in North America causes the major peanut allergen, Ara h2 to become a stronger digestive enzyme inhibitor and more resistant to digestion. Boiling peanuts, as is done in China, does not cause this affect. The allergy can last a lifetime, however new research has shown that almost 25% of children will outgrow a peanut allergy. Society is helping in the protection of allergic children banning peanuts in many school districts. There is now an experimental drug being tested to combat this allergy, called TNX-901.
As the peanut is a member of the pea family unrelated to other nuts, individuals with peanut allergies may not be alergic to the other types of nuts, and vice-versa.
U.S. Department of Agriculture Program for Peanuts
George Washington Carver, an American agricultural researcher, was the first to identify more than 300 different uses for peanuts (which, contrary to popular belief, did not include peanut butter) and is generally credited with introducing peanuts to the United States food market. He encouraged cotton farmers in Alabama to grow peanuts instead of, or in addition to cotton, because cotton had leached so much nitrogen from the soil, and one of the peanut's properties as a legume is to put nitrogen back into the soil (a process known as nitrogen fixation). His purpose in identifying a variety of uses was to encourage the growth of demand for the peanut so it could become a viable cash crop alternative to cotton.
Using the results of Carver's studies, peanuts were designated by the U.S. Congress to be one of America's basic crops. In order to protect domestic industry by keeping prices artificially high, the United States Department of Agriculture (USDA) conducts a Program for Peanuts . Two USDA programs for domestic peanuts are the Price Support Program and the Production Adjustment Program (National Poundage Quota). The Price Support Program consists of a two-tier price support system that is tied to a maximum poundage quota. Domestic peanuts produced subject to the poundage quota are supported at the higher of two prices, while peanuts over quota or those produced on farms not having a quota are supported at the lower rate. The quota support price acts as a floor price for domestic edible peanuts. For producers who fail to fill their quota in any given year, there is a maximum 10 percent over marketing allowance for the subsequent year. Pursuant to the program, producers may place peanuts under nonrecourse loan with the Commodity Credit Corporation (CCC) at the designated support price or they may privately contract for the sale of their crop. It is also illegal under Federal Law to grow peanuts on more than one acre of land for commercial consumption. This effectively creates a peanut monopoly, as it is not economically feasible to grow peanuts on only one acre of land, while drastically increasing prices.
The major producers/exporters of peanuts are the United States, Argentina, Sudan, Senegal, and Brazil. These five countries account for 71 percent of total world exports. In recent years, the United States has been the leading exporter of peanuts. The major peanut importers are the European Union (EU), Canada, and Japan. These three areas account for 78 percent of the world's imports.
Although India and China are the world's largest producers of peanuts, they account for a small part of international trade because most of their production is consumed domestically as peanut oil. Exports of peanuts from India and China are equivalent to less than four percent of world trade.
Ninety percent of India's production is processed into peanut oil. Only a nominal amount of hand-picked select-grade peanuts are exported. India prohibits the importation of all oil seeds, including peanuts.
The European Union is the largest consuming region in the world that does not produce peanuts. All of its consumption is supplied by imports. Consumption of peanuts in the EU is primarily as food, mostly as roasted-in-shell peanuts and as shelled peanuts used in confectionery and bakery products.
The average annual U.S. imports of peanuts are less than 0.5 percent of U.S. consumption. Two thirds of U.S. imports are roasted, unshelled peanuts. The major suppliers are Singapore, Taiwan, Malaysia, Hong Kong, Mainland China, and Canada. The principal suppliers of shelled peanut imports are Argentina and Canada. Most of Canada's peanut butter is processed from Chinese peanuts. Imports of peanut butter from Argentina are in the form of a paste and must be further processed in the U.S. Other minor suppliers of peanut butter include Malawi, China, India, and Singapore.
Approximately fifty percent of all peanuts produced in the United States are grown within a 160 km (100 mile) radius of Dothan, Alabama. Dothan is home to the National Peanut Festival established in 1938 and held each fall to honor peanut growers and celebrate the harvest.
- List of edible seeds
- Jimmy Carter, a peanut farmer who became President of the United States of America
- George Washington Carver, a prominent American botanist
- peanut butter and jelly sandwich
- Vitamin E
- Mr. Peanut
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