Crops domestication

The species known as sugar beet is a subspecies of Beta vulgaris of the Amaran-thaceae family. It is a biennial, hybrid crop domesticated from wild beets to obtain high sugar content that are stored in the root. 

Dempewolf, H., Rieseberg, L.H., Cronk, Q.C., 2008. Crop domestication in the Compositae a family-wide trait assessment. Genet. Resour. Crop Evol. 55, 1141-1157. 

G. Maniok Tapioka R manioc C. is a tropical root crop, domesticated in South and Central America. Wide distribution in many tropical countries in Afiica and Asia. C. is a shrubby, woody, short-lived - perennial, 3 m in height, which is easily propagated fiom stem cuttings. Leaves are large, deeply lobed and dark green. 

Another centre of crop domestication was sub-Saharan Africa but evidence is scarce. Diamond (2002) recognises three centres of plant domestication tropical West Africa, the Sahel and Ethiopia. Tef, a cereal, derives from the latter while pearl millet and sorghum, also a cereal, originated in... 

Caffeine. About 3% by weight of the roasted coffee bean is caffeine (16). The second U.S. Department of Agriculture world coffee crop estimate for 1988—1989 was 4.24 x 10 kg (93.3 million 100-lb bags) (102). World coffee consumption was predicted to rise in the foreseeable future at the rate of 1—2% per year and thus the total amount of caffeine and related alkaloids ingested from this source can also be expected to increase. Caffeine and related bases (eg, theophylline) are also found in various teas but, because most of the major producers (India, China, etc) export relatively Htfle of thek crops and keep most for domestic consumption, accurate figures on year-to-year production are more difficult to obtain. Nevertheless, these crops are of significant economic import (103). 

English or Persian Walnuts. Walnuts are produced in more countries than any of the other tree nuts but production figures are unrehable. The United States is the leading producer of walnuts, at 234,913 t in 1990—1991 (valued at 279,720,000). Production, mostly in Califomia and Oregon, is nearly one-half of the world total. Many countries produce substantial quantities of walnuts. The USDA considers estimates of the commercial crop more rehable than the total yearly production figures, which in 1990—1991 were 152,500 t in China, 66,000 t in Turkey, 17,000 t in India, 13,000 t in Prance, and 12,000 t in Italy. Walnuts, both in-sheU and shelled, may be imported from many countries, eg. Prance, Italy, China, Turkey, and India. Most imported walnuts are smaller than domestic walnuts and are used by the confectionery and baking industries. 

Pecans. Pecan is the most important horticultural crop native to North America (163). The United States is the only substantial producer of pecan, despite the fact that pecans have been introduced into AustraUa, Israel, South Africa, and Argentina. The principal producing states, from high to low, are Georgia, Texas, New Mexico, Louisiana, Alabama, Oklahoma, Mississippi, North Carolina, South Carolina, Florida, Arkansas, and California. Domestic production of 135,597 t/yr in 1990—1991 was valued at 308,954,500 (153). 

The group of tests that must be performed for each pesticide depends on how that pesticide is to be used. For example, if a pesticide is not used on food or feed crops, extensive residue and metaboHsm tests in plants and domestic animals might not be required. Similarly, if a pesticide is not used in field crops nor on other extensive outdoor areas, aH the environmental fate studies might not be required. 

Sodium selenate has been used on a small scale in commercial greenhouses, primarily for growing carnations and chrysanthemums. It is transformed by the plants into volatile selenides, which repel red spiders, mites, thrips, and aphids (see Insect control technology). Sodium selenite is not intended for crops which could ultimately be used as food for humans or domestic animals. 

Soybeans are the most important oilseed in international trade. The United States, Bra2il, and Argentina are the main suppHers to the export markets. In 1994—1995, United States exports of 22.0 x 10 metric tons represented 32% of the domestic production, 16% of the world crop, and 69% of the international trade in soybeans. The European Union, Japan, Mexico, and Taiwan were the largest importers of soybeans (51). Japan, which produces <5% of its soybean needs, is the largest single soybean customer of the United States. Japan imported 3.4 x 10 t in 1994 (51). The United States also exports processed soybean products, eg, oil and meal. For 1990—1993, an average of 47% of the crop was exported as whole beans and processed products. 

U.S. exports of the other oilseeds are smaller and foUow different patterns (50). Exports accounted for only 2—3% of the cottonseed crop and 16—31% of the processed oil production for 1991—1994. Of the peanut crop ca one-half is consumed domestically as whole nut products and 15—20% is exported. Only about 10% of the sunflower seed crop is exported. From 1991 to 1994 an average of 70% of the oil was exported, but only about 11% of the meal was shipped overseas. 

For the 1994 crops, 33 beet sugar factories in the United States processed 28.8 X 10 t of beets from 586,000 ha into 4.23 x 10 t (93 x 10 Cwt) of sugar 56% of the domestic production and 47% of the U.S. market. Cwt or hundred-weight of sugar is 100 lbs and is the common unit of commerce in the United States. This is a record level of production, an increase of 12% from the 1990 and 1991 crops. The average factory has a daily processing capacity of 4885 t compared to <3700 t in 1982. Since 1994, three factories in California have been closed and the constmction of one new factory has been announced for central Washington State. European factories process 10,000—15,000 t/d. 

The problems with jojoba as a commercial crop are the usual ones of domestication and cultivation. It is a slow-growing plant, available only in the wild and therefore has very wide genetic variabiUty. Efforts are underway to select the most promising variants and cultivate these as a crop in the southwestern United States deserts (7). A possible alternative for producing jojoba oil is to culture plant embryos in bioreactors (see Cell culture technology). 

Pests and Insecticides. The most destmctive pests of the cotton plant are the boU weevil and the boUworm/budworm complex. They are serious threats to the cotton industry in countries around the world. The boU weevil migrated from Mexico around 1892 and spread over the entire cotton belt within 30 years. The domestic cotton crop lost to the weevil is worth 200 million a year. In addition, about 75 million a year is spent for pesticides to control this destmctive pest (8). Unfortunately, some insecticides used to control the weevil kill many beneficial insects. Among the undesired casualties are insects that help to control the boUworm and the tobacco budworm, pests that cause another 200 million loss in cotton. 

The movement of fluoride through the atmosphere and into a food chain illustrates an air-water interaction at the local scale (<100 km) (3). Industrial sources of fluoride include phosphate fertilizer, aluminum, and glass manufacturing plants. Domestic livestock in the vicinity of substantial fluoride sources are exposed to fluoride by ingestion of forage crops. Fluoride released into the air by industry is deposited and accumulated in vegetation. Its concentration is sufficient to cause damage to the teeth and bone structure of the animals that consume the crops. 

Fertilization using animal products has been practiced since ancient times. Animal manure returns nutrients to the soil, replenishing elements that are depleted as crops are grown and harvested. It is likely that the use of animal fertilizers quickly followed the domestication of goats, sheep, and cattle. 

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