USDA-ARS Research Geneticist
Comments at 57th Summer Field Tour and Program
Texas Rice is Life
July 8, 2004
November 2003 began a year long celebration of the 50th year anniversary for the Agricultural Research Service. ARS is a federal agency whose roots go back to the creation of the Department of Agriculture in 1862 by President Lincoln's administration. The mission of the USDA was to "acquire and disseminate useful information on subjects related to agriculture to the people of the United States". In this same year, the government set aside over 13 million acres to establish the land grant college system that resulted in the creation of the State agricultural experiment stations. Over the next few years, various government bureaus were established within the USDA to address research issues in specific disciplines like botany, microscopy, and animal industry. In 1953, the same year that Watson and Crick published the double helix structure of DNA, these bureaus were merged to form the Agricultural Research Service. The mission of ARS is to develop new knowledge and technology that will sustain the production of food, feed, and fiber products that are of high quality, safe for consumers, and help sustain the economic viability of agriculture in our society. Today ARS is the largest science organization in the world dedicated to agricultural research. ARS employs over 2100 scientists that are working on some 1000 projects located in research laboratories across the nation. These projects are part of 22 national programs that are focused on addressing complex research issues in food safety, crops, animal science, human nutrition, and preservation of natural resources.
ARS has been a significant contributor to progress in agriculture and has developed a worldwide reputation for research which has benefited farmers, consumers, and the environment.
The following are a few highlights of USDA ARS accomplishments that have occurred in rice research over the last century.
At the turn of the 19th century rice cultivars were collected from Japan, Taiwan, Honduras, the Philippines, India, and Madagascar by federal envoys and were introduced into this country forming the basis of the US rice industry. In addition,some cultivars were obtained from participants from other countries that attended the 1904 World's Fair that took place in St. Louis, a century ago.
As rice production became established in the US, irrigation canal systems like the one that currently feeds into the Beaumont research station were created by local state and county governments.
In the Early 1900's field experimentation and demonstration trials were set up by the USDA in South Carolina, Arkansas, California, Virginia, and Texas. These studies were expanded in the 1920's and 1930's with the assignment of USDA scientists from specific disciplines in breeding, agronomy, weed control, cultural management methods, and pathology to conduct research in Arkansas, Texas, Louisiana, and California.
Some of the first rice cultivars developed through rigorous breeding efforts were released for production starting in the 1940's. These were tall, leafy, and late maturing cultivars that were able to shade out weeds in the rice fields and were harvested using hand operated binders. Bundles of rice were left to dry in the field, and then these were threshed with steam operated machines.
During WWII there was a scarcity of labor but an increasing demand for rice. This resulted in a need for greater mechanization in rice agriculture. After the war, the availability of WWII training airplanes and pilots soon facilitated the development of aerial application of agricultural chemicals. By 1946 fields were being seeded using airplanes. Just four years later, 90% of the Texas rice crop was being harvested by combines.
With the advent of combines, the rice crop needed to be harvested earlier and at higher moisture while the crop was still standing in the field. This led ARS researchers at the Southern Regional Research Center in New Orleans to determine the proper moisture level for harvest and the storage methods which would optimize milling yield. On farm and commercial rice driers were developed and the Southern Regional Research Center identified the best drying methods for storing and milling the rice. It was also during this time that the Southern Regional Research Center discovered that oil from rice bran was edible and nutritious; adding value to the rice crop.
In 1955 the ARS Rice Quality Laboratory was established at Beaumont as a result of demand from the industry for improved cooking quality in rice. As a service to the US rice industry, ARS evaluates thousands of breeding lines each year at Beaumont to make sure that new cultivars meet the high standards expected by consumers and the industry.
In 1957 National Seed Storage Laboratory was established in Ft. Collins, CO as a long term preservation center that currently holds over a quarter million crop varieties. This is one of 19 seed storage facilities in the US. Some 17, 000 rice genetic stocks have been collected from around the world and are maintained by ARS as part of this national germplasm system. They are grown out at Stuttgart, AR and stored in the National Germplasm Collection located in Pocatello, Idaho. ARS scientist Dr. Bob Dilday was instrumental in organizing and expanding this rice collection. These natural genetic resources offer promise in developing new rice cultivars that have improved resistance to diseases and insects that will reduce the need for pesticides and enhance nutritional quality which is important for a healthy diet.
The cultivar Belle Patna was released by ARS Scientist Hank Beachell in 1961. It was the first cultivar for the south that matured early enough to be ratoon (second) cropped. This significantly increased economic value to farmers. Soon "Propanil" herbicide was developed and allowed farmers to apply increased rates of fertilizer without increasing weed pressure. This drove breeders to develop shorter, lodging resistant cultivars which did not have to be as leafy to shade out weeds. However, with the increased use of fertilizers, increased pressure from diseases was observed.
In 1967, Ted Johnson, ARS researcher at Stuttgart, released Starbonnet which became a major rice cultivar and, at its peak, was grown on 67% acreage in AR.
Around 1970, ARS scientist Roy Adair released short statured medium grains for the California production system that allowed greater use of fertilizers and higher yield potential in this temperate environment.
In 1972, the cultivar Labelle was released at Beaumont, TX by Dr. Charles Bollich. This cultivar was very early, had better yield, was resistant to blast disease, and was shorter allowing higher fertilizer rates to be used. Labelle was a major variety in the south for over 20 years. . In addition, an ARS research project was established at Beaumont, under the leadership of Dr. "Toni" Marchetti, to improve the disease resistance of rice cultivars grown in the south.
In 1979, the cultivar Newrex was developed as part of a collaboration with Campbell Soup, Inc. This accomplishment opened door for developing other rice varieties for specific industry needs. Derivatives of Newrex include Rexmont and Dixiebelle which, over the years, have been used by the parboiling and canning industries because of their unique processing and canning quality.
Dr. Neil Rutger, who is currently the ARS center director at Stuttgart, AR, has had a long career in mutation breeding. In the 1980's semidwarf medium grains were developed through his research and more recently, mutants that have early maturity and unique quality traits have been developed from his research.
In 1983, the cultivar Lemont was developed by Dr. Bollich at Beaumont. Lemont is a semidwarf cultivar that demonstrated superior straw strength by being able to withstand hurricane force winds. Lemont revolutionized rice production in the south because of its high yield, excellent milling quality, and good resistance to blast disease. It was also found to produce higher parboiled rice yields which accounted for over 25% of the rice production market at that time. Today most of the rice cultivars grown in Texas, Louisiana, and Mississippi trace their parentage to Lemont.
In 1987, ARS scientist Hank Beachell and Gurdev Khush, from the International Rice Research Institute in The Philippines, won The Japan Prize for their development of semidwarf rice cultivars that brought the "green revolution" to rice. They were the first agricultural scientists to win this coveted prize. In 1994 Dr. Bollich was inducted into ARS Hall of Fame because of his career accomplishments in rice breeding. Two years later, Drs. Beachell and Khush won the World Food Prize. Although today Dr. Beachell is "90 something", he is still involved in rice research, and 30 years of his career in rice was as an ARS researcher in Beaumont, TX.
In addition to developing rice cultivars using conventional breeding methods, the ARS research program in Beaumont has been a leader in developing genetic markers that are linked to important traits in rice and can be used by breeders to facilitate the development of new rice cultivars. This technology was developed in partnership with Dr. W.D. Park at Texas A&M University in College Station and has been used to reduce the development time for new rice cultivars by several years. This technology will facilitate using the diversity of natural genes found among the 17, 000 rice genetic stocks collected from around the world that are maintained by ARS in the National Germplasm System. These natural genetic resources offer promise in developing new rice cultivars that have improved resistance to diseases and insects that will reduce the need for pesticides and will enhance nutritional quality which is important for a healthy diet.
This is a small glimpse of some of the accomplishments from ARS research in rice. These successes have come from the strong partnership that ARS has had with state agricultural experiment stations, like Texas A&M University, and with farmers, millers, and processors of the US rice industry. Such agricultural research has resulted in an affordable, safe, and abundant food and feed supply that has provided the stability for our nation to grow and prosper. 2004 is the International Year of Rice and the 50th anniversary of the establishment of ARS. This is an opportunity to reflect on some of the benefits that science has brought to our world.
By Dr. Shannon Pinson
It is often assumed that rice plants require a lot of water to grow because all rice in the US and many other parts of the world is grown under flooded conditions. In truth, however, even when surrounded by standing water, the rice plant does not require more water than would a wheat or barley plant grown in some areas of the world, rice is not grown in flooded fields, but under what is known as "upland" conditions. Rice that is kept watered but not flooded is also referred to as "aerobic rice".
So, why are rice paddies flooded? The primary reason rice is grown under flooded conditions is the water provides an environmentally friendly, non-chemical control of major weed species. Plant cell elongation and multiplication, processes necessary for plant growth, involve chemical reactions that require oxygen. Flooded fields have less oxygen available for plant roots than dry or aerated soils. Thus, the flood water applied to rice paddies is used to prevent the germination and growth of weeds that would otherwise compete with the rice crop for nutrients and light. Rice is a unique grass species that it is able to survive such flooded conditions. Rice leaves and stems have an internal air spaces, like a series of small tunnels, through which air is collected and passed down to the root cells. This is a survival mechanism common among aquatic plants. Rice plants need to have about one-third of their vegetative height out of the water for this to work. Although there are some types of rice that can grow in very deep water, most rice will die if all the leaves are covered with water for too long. The water level in rice paddies is carefully monitored and kept low until the plants have grown tall enough to keep the flood level at 4 to 8 inches in depth.
Rice reaps other benefits from the flood waters as well. Army worm and chinch bugs can be a problem in young rice fields, but these pests leave once the fields are flooded. Flood water also moderates fluctuations in field temperatures. Dark soil heats up faster and cools down faster than water does. This means the flood waters cool the rice plants during hot days, and warm the rice plants during cool nights. This is particularly useful in California where hot day-time temperatures regularly alternate with cool night-time temperatures because of lack of cloud cover to hold in heat.
Flooded rice paddies benefit the environment as well as the rice crop. Salt accumulation due to surface evaporation can become a problem with other irrigated row crops, and will cause the land to become sterile (no longer capable of supporting plant growth) if not rectified. In contrast, the flooding of rice prevents excessive salt accumulation. Allowing water to flow slowly through marsh plants is known to purify surface water. In some cases, properly managed rice paddies may actually serve as artificial wetlands and emit water that is cleaner than the incoming irrigation water. Much of the U.S. rice growing region also serves as an important habitat for waterfowl and migratory birds and is an example of how properly managed agriculture can enhance the environment.
Rice is a staple food crop for most of the world's population and is a natural source of good nutrition. Rice harvested from the field is called paddy, or rough rice, and it is shipped to a mill where the hulls on the grain are removed to produce brown rice. The outer bran layer of brown rice is high in fiber, B vitamins, and minerals like calcium, phosphorus, iron, sodium, and potassium. Although the bran layer contains most of the nutritious components of the grain, it is also a barrier to water absorption and is the reason why it takes about 45 minutes to cook brown rice. Most people prefer to eat white rice, that has had the brown layer removed by milling, because it takes only about 20 minutes to cook. Because white rice is rich in easily digestible carbohydrates and has very little protein, it is one of the first solid foods given to babies. To replace the nutrients that are lost from the brown rice during the milling process, most white rice is fortified with vitamins and minerals that are absorbed by the grain during cooking.
There are three typical types of rice found in the grocery store: long, medium, and short grain. One's choice at the grocery store will largely determine how the rice will cook up at home. Long grain rice cooks up light and fluffy, whereas medium and short grain rice tend to be moist and sticky after cooking. Long grain rice is preferred by most of the US population and is also commonly used in frozen dinners, canned soup, and seasoned packaged products. In contrast, medium and short grain rices are preferred for use in Asian cuisine partly due to the fact that sticky rice is easier to eat with chopsticks. In addition, medium grain rice is used in cereal manufacturing, whereas short grain rice is used in puddings. The primary reason why various types of rice differ in their cooking quality and use in food products is due to differences in the chemical composition of the starch in the rice grain.
Rice starch is made up of two components, amylose and amylopectin, that are intertwined and tightly packed into microscopic granules in the rice grain. During the cooking process, the starch granules absorb water and expand, forcing out the chains of amylose in a process called leaching. Once the rice is cooked and cooled, the leached amylose chains line up, lock together and form a gel. This locking process is very noticeable once the rice cools to room temperature because the starch "retrogrades" and becomes very firm. Thus, leftover cooked long grain rice that is stored in the refrigerator becomes very hard, whereas leftover medium or short grain rice remains relatively soft after cooling. Amylose is the major component of the starch that will determine the final cooked texture, stickiness, and glossiness of the rice. It also determines what type of food product it can be best used in. For example, rice that has a high concentration of amylose is particularly suited for canned soup products because it is very firm when it is cooked and loses little starch into the water during the canning process. In contrast, rice that has intermediate amylose content has a soft texture when cooked and is preferred as a table rice.
There are also specialty rices that possess unique flavors and cooking qualities. One of the most popular is aromatic rice. Rice, like other grain crops, possesses compounds that produce different aromas when cooked. One of these compounds, 2-acetyl-1-pyrroline, can be found in high concentrations is some rice varieties and gives a buttery or popcorn-like aroma and flavor. This characteristic is found in aromatic or scented rice products like "jasmine" and "basmati" rice. The basmati rice is also unique in that it has very slender grains that elongate dramatically when cooked. This type of rice is commonly used in Indian cuisine. Arborio rice is a very large, round grain with a large chalky (opaque) center. This type of rice is usually cooked briefly in oil, and then mixed with broth, sausage, seasoning, and vegetables to prepare the Italian dish, "risotto". It is believed that the large chalky grain absorbs the flavors of the other ingredients better than other kinds of rice. Rice with colored bran (purple, black, or red) not only has a unique texture and flavor, but is also high in phenolic content, an antioxidant, which is believed to have a beneficial effect on human health by protecting against oxidative damage which has been implicated in a range of diseases. In some Asian countries colored rices are served at ceremonial occasions and are used as a health supplement.
Whether you select brown, parboiled, pre-cooked, or milled rice or its co-products like rice flour, rice bran, or rice oil, there are many products using rice that meet our nutritional and culinary needs. The different flavor, texture, aroma, and appearance characteristics that are found in rice allow consumers a wide range of products to choose from at the grocery store.
Some rices are scented and smell like popcorn when cooked. This aroma is due to the presence of the naturally occurring compound 2-acetyl-1-pyrroline (2AP) which is also found in other plants such as peanuts and corn. The popcorn aroma is typical of basmati- and jasmine-type scented rices which command a premium price around the world because of their unique quality. The 2AP compound is expressed throughout the plant and can be smelled even when walking through a field of aromatic rice during the growing season. Ironically, 2AP is very similar to a pheromone that tigers use to mark their territory and ward off competitors (Nature 1990 344:26).