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Crop Science Sample LessonCS122 Rice
MAIN IDEA: What are the requirements for growing rice? COMMON AND SCIENTIFIC NAMES Rice is an annual monocot and a member of the grass family -- Gramineae. The scientific or botanical name for rice is Oryza sativa. Wild Rice is native to North America, and its scientific name is Zizania palustris -- a different genus than rice paddy or upland rice. VARIETIES AND FEATURES Common rice is lowland or paddy rice which requires continuous irrigation or flooded ponding. Upland rice is grown in nonflooded conditions. Rice is divided into short, medium and long grain varieties. Some of these varieties have distinct aromas, flavors and starch types. Different rice cultivars vary in maturity date or length of growing season as shown below:
Rice is further classified by cultural adaptation. Japonica is usually short-grained kernels and is grown in temperate zones. Indica is usually found in tropical climates, and it is typically long-grained. Some common cultivars include Katy, Newbonnet, Lemont, Texmont, Della, Dellmont, Gulfmont, Labelle, Mars, Rexmont, Skybonnet, Starbonnet and Tebonnet. When choosing a variety/cultivar, growers consider seed availability, date to be seeded, suitable maturity, resistance to lodging, desirable grain type, disease resistance, processing characteristics and yield potential. CLIMATIC REQUIREMENTS FOR GROWTH Rice thrives under the hot and humid conditions which characterize areas of the southern U.S. during the summer months. The rice-producing states within the United States include Florida, Arkansas, Louisiana, California, Texas, Mississippi and Missouri. Growing rice plants need plenty of sunlight and warm growing conditions. Extended temperatures below 55 F may result in poor grain formation. SOIL TYPES AND NUTRIENT REQUIREMENTS Paddy leveling and levee building are very critical to maintaining optimum and uniform paddy water depth. Soils must hold water well after flooding. Soil pH needs to be between 5.0 and 7.5. Fertilizer needs are determined by soil testing. Soil types suited for rice production preferably have subsoil of clay or plow pan, which reduce infiltration and water loss. Deep, sandy loam and silt loam soils could be less desirable because of the water lost by leaching during the initial flooding. But after the permanent flood has been established for two to three weeks, the water requirement for loam soils is about the same as for any other soil suited for rice production. PROPAGATION METHODS Rice is propagated from seed. The seed is pregerminated (sprouted) for aerial seeding methods. Rice seed is generally treated with a fungicide by the seed conditioner/dealer for control of seedling diseases. Several fungicides are registered for use as seed treatments. Rice is an aquatic crop and is flooded during its growing season. In growing areas with a rainy season, rice fields actually serve as temporary storage for this rainfall and allow for the gradual addition of this water back into the environment. Flooding is used to control some weeds and insect pests, but may lead to waterborne disease spread, some water weeds and some water insect pests. Typically, flooding begins when the rice seeds are tillering, although flooding at planting occurs in some instances. Rice fields are flooded when the rice plant is about six inches high. The flood is maintained two to four inches deep until the rice grain has matured and begins to dry out. The flood is drained prior to harvest to ensure firm ground for harvesting equipment. PLANTING Rice is planted in a level, well-prepared field. A grain drill, similar to what is used to plant other small grains, sows about 90 pounds of rice seed per acre. Some rice is seeded with an airplane. In areas with a long growing season like Florida, rice plants can be harvested and then allowed to regrow for a second harvest (also called a ratoon crop) which is regrown from young shoots or tillers. DISEASES AND PESTS Rice diseases are influenced by factors such as fertilization rate, soil type, environmental conditions and varietal susceptibility. Depending upon the severity, diseases can cause substantial losses in yields as well as decreased grain quality. Growers control certain diseases by using seed treatment, resistant varieties and fungicides along with cultural and management practices. The fungal disease blast is a serious problem for rice growers. The best control available is to plant blast-tolerant varieties, although some fungicide is used in case of high disease prevalence. Other diseases of rice include seedling blight, sheath blight, red rice, leaf spot, stem rot and root rot. When rice is grown as a rotation crop with sugarcane or vegetables, certain insects such as the rice water weevil have not become a problem. Insect pests include stinkbugs, rice water weevils, leafhoppers, thrips and grasshoppers. Fields are scouted and control measures with approved insecticides are started when population thresholds are exceeded. Stinkbugs are a major problem that must be controlled. Stinkbugs pierce the immature kernels with their proboscises and suck the juices, reducing the quality of the seed. The rice water weevil can also be major concern. The larvae stage causes the injury. These larvae can cause severe root pruning. Growers can control the larvae with properly timed insecticide applications. Insect-feeding birds and wading birds are welcome additions to rice fields. Blackbirds and bobolinks are not as welcome. Blackbirds not only pull up the new seedlings and eat the seed but they also eat the mature grain. Bobolinks are small, migratory, sparrow-like birds that eat large amounts of mature grain just before harvest. Both blackbirds and bobolinks can seriously reduce yields. Weeds are controlled by integrating cultural practices and herbicides. Field preparation includes complete weed removal through disking. Immediately after planting, an herbicide is applied that inhibits weed seed germination or kills growing weeds. As soon as the rice plants reach five to six inches in height, the flood is applied, further inhibiting weed growth. In some areas, rice is not planted on the same field two years in a row, in order to control problem weeds with normal crop rotation. WATER REQUIREMENTS Most people think of rice plants as being produced under flooded conditions because rice is well-adapted to a semi-aquatic habitat. Rice stems contain a specialized type of tissue called aerenchyma cells which facilitate air movement from the leaves to the roots by forming hollow tubes within the plant. Upland rice, however, is grown without being flooded. Upland rice produces significantly lower yields than paddy rice and requires abundant moisture at frequent intervals. Paddy rice is the preferable method for commercial rice production. The flooded culture of rice is not needed to supply unusually large amounts of water to the plant. Throughout its growing period the rice plant has a water requirement similar to that of other plants grown on dry land. Flooding is used to control some weeds and insect pests. Proper management of the quantities of water pumped onto a rice field is critical. Excessive water flowing across a rice field is not necessary and is a waste of water. GROWTH CHARACTERISTICS The rice plants develop new shoots (tillers) with the number of shoots depending on spacing and soil fertility. A single shoot appears first, followed by one, two and more offshoots. Each stalk has five or six or more hollow joints and a leaf is located at each joint. The leaf blades are long, pointed, flat and rather stiff. The highest joint on the plant grows a branched head called a panicle. This is similar to an oat plant, but it is more compact and it droops more. Each head bears from 50 to 300 flowers (spikelets) from which the grains develop. HARVESTING The length of time from planting to harvesting is determined by the rice variety and weather conditions. It takes an average of 120 days (90 to 120 days after planting, depending on variety) for the first crop to mature and another 85 days for the ratoon crop to mature. Rice fields are drained prior to harvest, returning much of the water to the environment. When the grain heads, called panicles, have tipped over and started to turn brown, the water is drained. After the water has been drained, the rice plant becomes fully brown within 7 to 14 days. At this point the rice is ready for harvest. Once the rice is mature and the fields have been drained, the rice field is harvested with a conventional grain combine. The moisture content of the rice kernel is about 19 percent at harvest -- too high for quality storage. Rice straw is either left in the field and tilled into the soil or baled and used for livestock. STORAGE AND USES After harvest, rice is dried by heated air that is forced through the rice until the moisture content has been reduced to 12 to 13 percent. The rice is then stored in silos or bins until it is milled and sold. Rice milling separates the outer portions of the kernel from the inner endosperm. Milling steps include cleaning, hulling, pearling, polishing and grading. Products of rice milling include brown rice (bran left on), milled rice, polished rice, parboiled rice (precooked), rice flour, flaked rice and rice oil. By-products from rice milling that can be used for livestock feeds include rough rice, brown rice, brewer's rice, rice bran, rice hulls, rice mill by-product, rice polishings and rice straw. EXERCISES: 1. Create a map of the United States that shows the growing areas for rice. 2. Report on rice production trends in the United States. For example, you could find information about yield, acreage and production in the United States. Use current and historical rice production statistics/graphics for the United States from the California Rice Growers Association Web site (California Rice Statistics report) or from the USDA National Agricultural Statistics Service Web site. Both sites are listed under Internet Resources. 3. Develop a presentation or a report on the history and/or culture of rice. Possibly narrow your presentation to its history in China, Japan or another Asian country. The following Web sites listed under Internet Resources will be useful: RiceWeb, A Guide to Thailand and MediumGrain Rice.com. Or just use a search engine such as Google to find the information. Be sure you note the source of your information and try to determine its reliability. 4. You have a field of 1,280 acres to seed. Approximately how many pounds of rice seed will you need? INTERNET RESOURCES:
** California Rice Commission - How Rice Grows
** California Rice Commission - California Rice Statistics and
Related National and International Data
** A Guide to Thailand - A Brief History of Rice
** International Rice Research Institute - Rice Knowledge Bank
** International Rice Research Institute - What Is Rice Milling?
** MediumGrain Rice.com - A History of Rice
** Mississippi State University Extension Service - Rice Production
** USDA National Agricultural Statistics Service (NASS)
** U.S. Rice Producers Association TEST: 1. Rice belongs to the __________ family and its scientific or botanical name is __________ __________ . 2. Wild rice, native to North America, is an ancestor of commercially grown rice. TRUE or FALSE? 3. A second harvest of rice also called a __________ crop can be regrown from young shoots or tillers.
4. Identify three factors growers consider when choosing a variety/cultivar of rice. 5. Rice fields are flooded when the rice plant is about __________ inches high, and the flood is maintained at __________ to __________ inches deep until the rice grain has matured. 6. Rice production requires that the field be flooded. TRUE or FALSE?
7. Name two insects that can be a major problem in rice production. 8. How are weeds controlled in a rice field? 9. On the average, rice is harvested __________ to __________ days after planting. 10. What is the moisture content of stored rice?
---------------------------------------------------------------------------- END STUDENT SECTION CS122 RiceTEACHER'S GUIDEOBJECTIVE: Students should be able to describe rice production methods.
PREPARATION: Take the following steps to prepare for this lesson: REFERENCE: Parker, Rick. "Introduction to Plant Science." Albany, New York: Delmar Publishers, 2000. INTERNET RESOURCES:
** California Rice Commission - How Rice Grows
** California Rice Commission - California Rice Statistics and
Related National and International Data
** A Guide to Thailand - A Brief History of Rice
** International Rice Research Institute - Rice Knowledge Bank
** International Rice Research Institute - What Is Rice Milling?
** MediumGrain Rice.com - A History of Rice
** Mississippi State University Extension Service - Rice Production
** USDA National Agricultural Statistics Service (NASS)
** U.S. Rice Producers Association IMPORTANT TERMS: aerenchyma cells, paddy, pregerminated, levee, ratoon, spikelets, tillers, thrips, upland rice. EXTENSION IDEAS: 1. Use current and historical rice production statistics/graphics for the United States for classroom discussion. You should be able to find information from the California Rice Growers Association or USDA National Agricultural Statistics Service Web sites listed under Internet Resources. 2. Cook rice and have students learn to eat the rice with chopsticks as you begin the discussion of the production of rice and its importance as a food to many cultures. 3. Have students do a "scavenger hunt" to find human foods that contain rice. Some examples are cereals, rice cakes, rice flour, rice drink (Horchata) and so on. Create a bulletin board display of all the labels from foods containing rice. 4. Guide students in creating a bulletin board display showing the steps and equipment used in the milling of rice. Information on the milling of rice can be found in a food science book, from an encyclopedia, or by searching the Internet and finding sites like the International Rice Research Institute Web site listed under Internet Resources. EXERCISE ANSWERS: 1. Using a United States map, students can correlate the text of the lesson with the location of the rice-growing states. This could be further refined by having the student determine the regions within the states where rice is grown. 2. Reports on rice production will vary and students could be assigned different aspects of rice production. For example, reports could cover yield, acreage and trends. Using the Web sites listed will require the students to do a little research to find the information that they need. 3. Reports or presentations on the history of rice culture will vary. Because of the importance rice holds as a food in many areas, there should be enough information that students can all find something different for their reports. 4. Answer = 1,280 acres X 90 pounds per acre = 115,200 pounds of seed. TEST KEY: 1. Rice belongs to the Gramineae family and its scientific or botanical name is Oryza sativa. 2. Wild rice, native to North America, is an ancestor of commercially grown rice. TRUE or FALSE? FALSE, wild rice is from a different genus. 3. A second harvest of rice also called a ratoon crop can be regrown from young shoots or tillers. 4. Identify three factors growers consider when choosing a variety/cultivar of rice. The following were listed in the lesson: seed availability, date to be seeded, suitable maturity, resistance to lodging, desirable grain type, disease resistance, processing characteristics and yield potential. 5. Rice fields are flooded when the rice plant is about six inches high, and the flood is maintained at two to four inches deep until the rice grain has matured. 6. Rice production requires that the field be flooded. TRUE or FALSE? FALSE. For paddy rice growing, flooding is not required, but is used to control some weeds and insect pests. Upland rice is not grown with flooding.
7. Name two insects that can be a major problem in rice production. 8. How are weeds controlled in a rice field? The lesson covers several methods, including water covering the field, herbicides, disking and crop rotation. 9. On the average, rice is harvested 90 to 120 days after planting. 10. What is the moisture content of stored rice? 12 to 13 percent CROSSWORD PUZZLE ANSWERS:
Across: 1. Spikelet, 4. Brown, 6. Tiller, 7. Thrip, 9. Paddy, 10. Japonica, 11. Blackbird, 12. Upland, 13. Grass. END TEACHER'S GUIDE
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