Shifting from a hunter-gatherer society to an agrarian society led to increasingly larger-scale agricultural production that involved selecting local crops for domestication. In recent history there has been a reduction in the number of agricultural crops grown for human consumption. There are estimated to be at least 20,000 species of edible plants on earth, out of more than 350,000 known species of higher plants. However, only a handful of crops feed most of the world's people. These include wheat, rice, corn, potatoes, sugar beets, sugarcane, cassava, barley, soybeans, tomatoes, and sorghum. Rice, wheat, and corn together account for a majority of calories consumed. In the effort to develop experimental crops, agricultural goals include expanding the diversity of plant food in the human diet.
Recent Successes
Soybeans (Glycine max) are a relatively new crop that gained worldwide acceptance and widespread cultivation in the second half of the twentieth century. Originally cultivated in China, soybeans gradually spread throughout Asia and became a staple food there. High in protein, soybeans were first grown in the Western world as animal feed. Concerted breeding efforts have resulted in many locally adapted varieties. Today, soybeans as both meal and oil are commonplace. Worldwide soybean production is now the greatest of any legume.
Triticale (x Triticosecale) is a hybrid created to combine the ruggedness and high protein content of rye (Secale cereale) with the high yield of wheat (Triticum aestivum). Triticale has not replaced wheat or rye in bread-making due to its rather low gluten content but is used to supplement bread flours. Triticale is also adaptable to marginal agricultural soils.
Kiwifruit (Actinidia deliciosa) is another recent success story. A previously little-known fruit originally called Chinese gooseberry, it was introduced to New Zealand at the turn of the twentieth century and renamed kiwifruit. The name change was a marketing strategy that led to worldwide popularity. Today kiwifruit cultivation and consumption are increasing worldwide. Kiwifruit grows on a deciduous vine, much like grapes. It can be harvested and then stored for several months without loss of quality.
Grains and Cereals
Quinoa (Chenopodium quinoa) is a grain native to the Andes Mountains of South America. It has been a staple in the diets of people living in that region for centuries. Although the leaves are edible, it is principally the tiny seed which is consumed. The seeds contain high amounts of protein, calcium, phosphorus, and the essential amino acid lysine, which is typically lacking in other cereals such as wheat, rye, and barley. Quinoa seeds must be washed or otherwise processed to remove the bitter saponins contained in the pericarp and can then be cooked and eaten much like rice. Quinoa can also be ground into flour as a supplement for bread making. Cultivation and use of quinoa have increased steadily since the 1980's.
Grain amaranths (Amaranth) are being rediscovered and developed as a potential new source of grain. Amaranth was a staple crop for centuries in Mexico, Central America, and South America. Amaranth is grown as an annual and yields thick, heavy seed heads containing numerous tiny seeds. The hard seed coat is removed by heating or boiling and can be prepared much like corn. Amaranth is comparable to other grains in protein, contains high amounts of lysine, and can be consumed by those allergic to typical grains. Breeding efforts over the last few decades involving A. hypochondriacus, A. cruentus, and A. hybridus have greatly increased seed yield as well as desirable plant growth habit. Another important characteristic is amaranth's drought resistance.
Legumes
Members of the Leguminosae family are particularly valuable as food sources because they contain high levels of protein. This is in part due to their ability to fix atmospheric nitrogen in root nodules that contain nitrogen-fixing bacteria. This symbiotic relationship with the bacteria means relatively little nitrogenous fertilizer is required for agricultural production of legumes. Tarwi (Lupinus mutabilis) is a legume native to the South American Andes that has a high protein and oil content, similar to the soybean. Tarwi is also high in the essential amino acid lysine. It grows well in poor soils and is drought-resistant. Current breeding efforts focus on reducing the bitter alkaloids, which can be removed by rinsing in water.
The winged bean (Psophocarpus tetragonolobus), native of tropical Asia, is entirely edible - leaves, flowers, seeds, pods, and tuberous roots. Like most legumes, the winged bean has a high protein content. This species could have tremendous potential in many tropical regions of the world, rivaling the success of the soybean.
A native of North America, the groundnut (Apios americana) was a major food source of many American Indian tribes. It is purported to have been offered to the Pilgrims to avert starvation. The numerous underground tubers can be prepared (cooking is necessary) like potatoes yet have a much higher protein content.
Several other legumes whose use and acceptance are likely to increase include the tepary bean (Phaseolus acutiflius), the pigeon pea (Cajanus cajan), and the bambara groundnut (Voandzeia subterranea).
Other Crops
There are many other potential food crops. Most have been cultivated on a small scale for years and are being rediscovered and researched for commercial production. Some of these include potato-like oca tubers (Oxalis tuberosa), fruits such as cherimoya (Annona cherimola), pepino (Solanum muricatum), and feijo (Acca sellowiana), and nuts such as egg nut (Couepia longipendula).
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