High-yield Crops

High-yield Crops
High-yield Crops
High-yield agricultural crops are those that have been bred, genetically modified, or fertilized to increase their production yields.

The health and well-being of the world’s growing population are largely dependent on the ability of the agricultural industry to raise high yielding food and fiber crops. No one knows for certain when the first crops were cultivated.

At some time in the past, people discovered that seeds from certain wild grasses could be collected and later planted where they could be controlled during the growing process and eventually harvested for food. Agriculture was firmly established in Asia, India, Mesopotamia, Egypt, Mexico, Central America, and South America at least six thousand years ago.

Development of Modern Agriculture

Farming practices have under gone many changes, but until the nineteenth century most farms and ranches were family-owned, and people primarily practiced subsistence agriculture.

Just as in almost all other industries, the arrival of the Industrial Revolution dramatically changed the agriculture industry. Inventions such the cotton gin in 1793, the mechanical reaper in 1833, and the steel plow in 1837 led the way to mechanization of most farms and ranches.

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The Industrial Revolution produced significant societal changes, as people involved in agricultural production left the farms to work in city factories. Fewer and fewer people were required to produce more and more agricultural crops for an increasing number of consumers.

As the population continued to grow, it became necessary to select and produce higher-yielding crops. The Green Revolution of the twentieth century helped make this possible.

Agricultural scientists developed new, higher-yielding varieties of numerous crops, particularly the seed grains. Tremendous increases in the global food supply resulted from the use of these higher-yielding crops, along with improved farming methods.

Improved Yields

Improved Yields
Improved Yields
There are two major ways to improve yield in seed grains such as wheat: produce more seed per seed head or produce larger seeds. Numerous agricultural practices are required to produce higher yields, but one of the most important is the selection and breeding of genetically superior cultivars.

When a plant with a potentially desirable gene mutation appears to improve a yield characteristic, seeds are collected and studied to see whether they consistently produce plants with higher yields.

This selection process remains one of the major means of improving yield in agricultural crops. Advances in the understanding of genetics have made it possible to breed some of the desirable characteristics that have resulted from mutation into plants that lacked the characteristic. In addition, the advent of recombinant DNA technology makes it possible to transfer genetic characteristics from one plant to any other plant.

The high-yielding varieties led to an increased reliance on monoculture. This practice of growing only one crop over large areas has made efficient, mechanized farming possible, with relatively few workers.

It has also decreased the genetic variability of many agricultural plants, increased the need for commercial fertilizers and pesticides, and produced an increased susceptibility among crops to damage from a host of biotic and abiotic factors. For example, most pests prey upon specific plant species.

If many fields are planted in one crop, the entire farm—and possibly the whole community—is susceptible should a pest strike. The corn blight that destroyed more than 15 percent of the North American crop in 1970 would have been less severe if a single cultivar of corn had not been so heavily planted in the United States.

The major high-yielding crops, in terms of land devoted to their culture and the total amount of produce, are wheat, corn, soybeans, rice, potatoes, and cotton. Each of these crops originated from a low-yielding native plant that was gradually converted into one of the highest-yielding plants in the world.

High-Yield Grains

High-Yield Grains
High-Yield Grains
Throughout the world, large portions of agricultural land are devoted to the production of wheat (Triticumsativum).Wheat is the staple of forty-three countries and 35 percent of the people of the world. It also provides 20 percent of the total food calories for the world’s population.

The cultivation of wheat is older than the written history of humankind. Its place of origin is unknown, but many authorities believe wheat may have grown wild in the Tigris and Euphrates Valleys and spread from there to the rest of the Old World.

Wheat is mentioned in the first book of the Bible, was grown by Stone Age Europeans, and was reportedly produced in China as far back as 2700 b.c.e. Wheat is widely adapted throughout the world and can grow in many climates; about the only places where wheat does not grow are those with climates that are continually hot and moist.

The total production of rice (Oryza sativa) is similar to that of wheat, and it is the principal food crop for nearly half of the world’s population. Rice has been under cultivation for so long that its country of origin is unknown; however, botanists believe that the plant originated in Southeast Asia. Rice was being cultivated in India as early as 3000 b.c.e. and spread from there throughout Asia.

Although rice is currently produced on all continents, more than 90 percent of the total world crop is grown in Asia. Rice was introduced into the United States in 1694, and the total U.S. crop is produced in just six states.

The per capita consumption of rice is less than 10 pounds per person in the United States; however, in some Southeast Asian countries, the percapita consumption can be as high as 325 pounds per person.

Corn (Zea mays) ranks third behind wheat and rice in world production of cereal grain. Corn may be the Americas’ greatest contribution to agriculture. The earliest traces of the human use of corn date back to about 5200 b.c.e.

It was probably first cultivated in the high plateau region of central or southern Mexico and was the basic food plant of all pre-Columbian advanced cultures and civilizations, including the Inca of South America and the Maya of Central America.

Corn is still produced primarily in the Western Hemisphere, although some is produced in Europe. It makes up more than 50 percent of the acreage devoted to all seed grains in the United States.Of the total grain crop produced, approximately 85 percent is fed to animals.

High-Yield Potatoes, Soybeans, and Cotton

High-Yield Potatoes, Soybeans, and Cotton
High-Yield Potatoes, Soybeans, and Cotton
The potato (Solanum tuberosum) is the New World’s second gift to world agriculture. The white potato is capable of nourishing large populations, especially in cooler regions where many other crops will not grow. It contains large stores of energy, high-quality protein, and valuable minerals and vitamins.

Potatoes are indigenous to South America and probably originated in the central Andean region. The potato has become one of the world’s great food crops because it combines, in one crop, the desirable characteristics of high yield, low cost, and nutrition as well as palatability.

Potatoes are grown in practically all countries of the world. As the potato is better adapted to cool, humid climates, total production and average yields are much higher in northern Europe than in the United States.

Soybeans (Glycine max) have been an important food crop in Asian countries, particularly China and Japan, since long before the time of recorded history. Soybeans will grow in nearly all soil types except extremely deep sand and are adapted mainly to temperate regions with fairly humid, warm growing seasons. Hence, soybeans are now grown in much of the New World.

Cotton (Gossypium), with a total annual production of more than 13 million tons, is by far the most important fiber crop in the world. Humans heavily rely on it for clothing and other textiles. Cotton enters the daily life of more people than any other product except salt.

Cotton fiber has been known and highly valued by people throughout the world for more than three thousand years. Like most crop plants that have been in cultivation a long time, cotton has an obscure origin. A vigorous cotton industry was present in India as early as 1500 b.c.e. From India, the cultivation of cotton spread to Egypt and then to Spain and Italy.

In the New World, a different species of cotton was being grown in the West Indies and South America long before the Europeans arrived. Although cotton is native to tropical regions, it has been adapted to humid, subtropical climates where there are warm days, relatively warm nights, and a frost-free season of at least two hundred days.

Genetic Engineering

The importance of plant nutrition was discovered during the nineteenth century, and the use of fertilizers has dramatically increased crop yields. Advances in the understanding of genetics in the early part of the twentieth century made it possible for people to breed desirable characteristics into plants, and people began to breed plants to increase yields.

At about the same time, the development of large-scale chemical synthesis and processing made it possible to produce a variety of chemical agents to control plant pests, but many of these chemicals were found to be hazardous to the environment.

Developing plants with high natural resistance would decrease the reliance on chemical pesticides, so plant breeders started to breed not only for increased yields but also for increased resistance.

Plant breeders began to examine older, abandoned cultivars, discarded breeders’ stock, wild plant relatives, and native or foreign cultivars and occasionally induced mutations for increased yields or resistance to pests.

When a particularly attractive trait was found, genetic crosses were made until progeny that showed improved yields and increased resistance were obtained. These developments in plant resistance have been partially responsible for the tremendous advances in the production of high-yield crops during the last half of the twentieth century.

To copewith the need for crop varieties that will both provide higher yields and exhibit greater resistance to pests and disease (thus avoiding the use of too many chemicals), new biotechnologies, including genetic engineering, are being refined.

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Total crop production can also be raised by using biotechnology to engineer plants that will flourish under what may have previously been considered marginal growing conditions, such as salty soil.

As the population grows, the agricultural industry will feel the pressure to produce more food, with the added element of pressure to make crop production more friendly to the environment. Biotechnology has the potential to play a major role in the development of a long-term, sustainable, environmentally friendly agricultural system.

The future development of higher-yielding crops that can be harvested mechanically and the production of new types of equipment to facilitate the harvesting process will also be important improvements in the production of high-yielding crops.

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