The Other Grasses – Rice and Corn Rice is the 2 nd most important cereal crop.

1. The Other Grasses – Rice and Corn Rice is the 2nd most important cereal crop. About 11% of arable land is devoted to rice production. That production is about 370 million metric tons/year. Almost 1/3 of the human population depends on rice as their principal food source. Rice was domesticated and first cultivated ~11,500 years ago in eastern China and India virtually simultaneously. In both places the species domesticated was Oryza sativa. There is a different congener, O. glabberima, that originated and is grown in Africa. It is believed that rice evolved in lowland tropical areas, and evolved means to survive the periodic flooding that occurs there.

2. Rice plants: live and in drawings from the Linnean herbarium

3. The adaptations rice evolved to survive flooding are air chambers that permit air (O2) to reach continuously from stomates in leaves through stems to portions of the plant (stems, roots) below water level. Rice is not dependent on growing in flooded paddies. In many places (here Georgia, U.S.) rice is grown without flooding. Most rice, however, is grown in paddies in water 5 – 10 cm deep. There are also special varieties of deep water rice (DWR) that grow in 2 m depth or more (called floating rice).

4. Rice grown in standing water avoids certain types of pests, e.g. weeds, but is subject to a variety of diseases: pathogens, rusts, and small insects (thrips) are at the top of the list. Not all weeds are problems. There is a mutualistic association between an aquatic fern, Azolla, and a photosynthetic cyanobacterium, Anabaena azollae, that contributes nitrogen and reduces the need for fertilization in growing rice. That’s Azolla around the rice plant. This is an example of multicropping. The ducks feed on Azolla (and on the rice), but become a second crop from the same paddy.

5. Rice is a monocarpic (single seed crop) annual plant. Harvesting and planting must occur annually. Pollination is by wind. There is a limited capacity for self-pollination, but mostly successful pollination comes from outcrossing. There has been enormous effort to develop rice varieties for differing environments and characteristics. It all begins with a wild progenitor from the foothills of the Himalayas in Asia, Oryza rufipogon. From it the two major Asian rice ‘groups’ were developed: Oryza sativa var. indica on the Indian side of the mountains and Oryza sativa var. japonica on the Chinese side. In China, at least, the wild rice was collected and the domesticated variety produced by ~ 7,500 (Diamond) to 7,000 (Crawford and Shen) YBP.

6. In Africa rice cultivation is more recent, going back ~3,500 years. In the Near East rice cultivation began around 800 BC, and then it spread to Europe, but was not widely grown until the 15th century. Rice (Oryza glaberima) came from Africa to the New World in (a very specific) 1694. It began in the Carolinas, expanded, collapsed with the end of slavery, then picked up again further west (Louisiana, Arkansas, Texas). World production of rice was approximately 700 million tons in 2005. Leading producers: China 185 million tons India 129 Indonesia 54 Bangladesh 40 Vietnam 36

7. Rice is commercially prepared by first removing the chaff (“hulling” the rice). The result is brown rice. White rice continues the process, removing the germ and bran. White rice is then “polished” with glucose or talcum powder. Due to the potential for asbestos contamination, talc polishing is no longer legal in North America. White rice is frequently enriched to restore vitamins and minerals lost in removal of bran and polishing. Nutrients in 100 g of : white rice brown rice Carbohydrates 79g same Fat 0.6g same Protein 5.2 – 7.6g 8.5 – 9.5 g Vitamin B6 0.15mg same other vitamins thiamine, B1

8. Relative consumption of rice: 3 Kg/person/year in the U.S. 160 Kg/person/year in Asia Characteristics of the two main rice types: Oryza sativa var. indica - long-grained, less ‘sticky’ due to lower amounts of amylopectins, grown in tropical and semi-tropical environments. It can be grown in 3-4 months, and thus produce several crops per year.

9. Oryza sativa var. japonica – short-grained, more ‘sticky’ due to larger amounts of amylopectins, grown in temperate environments, flowers as a ‘short-day’ plant, thus likely one crop per year. Many cultivars: long-grained and aromatic Basmati, medium-grained Patna, a hybrid of Basmati and long-grained American rice called Texmati, black and red cultivars from Indonesia. Unhulled, short grain Japanese rice

10. Black rice Golden rice Red rice

11. There is a third type (not another cultivar) called Oryza sativa ssp. Javanum that is not widely cultivated, but is regarded by rice geneticists as a rich source of new genes to use in selecting new varieties. Among the results of variety selection: higher yields, disease resistance, and a “golden rice” that synthesizes β carotene in the endosperm. Production of golden rice in developing countries could enormously reduce vitamin A deficiency diseases (and vitamin deficiency blindness). How many varieties are there? IRRI (International Rice Research Institute in Los Baños, Philippines) houses 67,700 Asian cultivars; 26,000 African cultivars; >1000 wild strains

12. “Wild” rice varieties in North America are no relation to Oryza. Zizania aquatica andZizania texana, the types of wild rice you could buy in a store, are still mostly harvested from the wild by First Nations collectors in small boats. Attempts to cultivate wild rice have, in general, been failures.

13. Corn is the 3rd most important cereal crop. Linneaus gave corn its proper binomial, Zea mays, and maize is its common name throughout the Americas. Corn evolved from Zea mexicana or teosinte. There are apparently three other wild species of Zea; all are native to Mexico and northern Central America. Races are indigenous to Columbia, Peru, Chile, Arizona and New Mexico. It is thought that maize actually evolved from one race of teosinte, Zea mays ssp. parviglumis whose genetic sequence almost indistinguishable from modern maize. This race is from the Balsas River basin in the Michoacan-Guerrero border region of western Mexico. After origin, maize seems to have diversified into a number of different races in the course of domestication.

14. Map of Mexico

15. Maize differs from the other grasses considered; it is monoecious, with male and female flowers separate on the plant. The male (staminate) flowers are at the top of the stalk (culm) and are commonly called the tassel. The remnants of the pistillate (female) flowers are the corn silk you clean from the ear before cooking and eating it.

16. There are a number of types of corn grown. They can be sorted out by intended use, and by the nature of the starch stored in the grains. The starches are: • Amylose – a nearly unbranched chain of glucose molecules, “hard” starch and • Amylopectin – a highly branched chain of glucose, “soft” starch • The basic types of corn are: • Popcorn – (Zea mays everta) - hard starch on the outside surrounding a soft starch core. This is very old, and may be the most primitive type. Popcorn pops because unlike most other grains, the outer hull, or pericarp, of the popcorn kernel is both strong and impervious to moisture.

17. As the kernel is heated past the boiling point, water in the kernel turns to superheated, pressurized steam, contained within the moisture-proof hull. Under these conditions, the starch inside the kernel softens and becomes pliable. The pressure continues to increase until it reaches the breaking point of the hull: a pressure of about 135 psi, or 9.1 atmospheres. The hull ruptures rapidly, causing a sudden drop in pressure inside the kernel and a corresponding rapid expansion of the steam, which expands the starch and protein of the endosperm into an airy foam.

18. 2. Dent corn – (Zea mays indenata) – used in livestock feed, industrial products, and processed food. This is commonly called “field” corn. The name dent comes from the change in shape of the kernels as the corn matures. 3. Flint corn – (Zea mays indurata) - also known as Indian corn, is used for similar purposes as dent corn. Flint corn is distinguished by a hard outer shell and kernals with a range of colors from white to red.

19. 4. Sweetcorn – (Zea mays saccharata) - Sweet corn is extra sweet because it contains more natural sugars than other types of corn. (Field corn contains 4% sugar at the same stage standard sweet corn contains 10% sugar.) Almost 50% of the sugar can be converted to starch only 24 hours after sweet corn is picked, so it is best to eat it fresh! 5. Flour corn – (Zea mays amylacea) - is used in baked goods. It has a soft kernal that is easy to grind. Flour corn is primarily white, although it can be grown in other colors, for example, blue corn. One of the oldest types of corn, flour corn was a chief type grown by native Americans.

20. Products from maize include: corn oil (unsaturated), margarines corn syrup cornstarch adhesives, sizing, bulkers beer, bourbon, Canadian (Club) whiskey silage (animal feed) industrial material (cellulose for rayon etc.) corn extract: nutrients for antibiotic production organic acid production (acetic, citric, butyric acids) ethanol additive to gasoline (now 10% in regular gas)

21. In terms of human consumption and nutrition there are a large variety of applications: • succotash = corn + boiled beans • popcorn – was known and used by Incas (don’t need to grind popcorn to get at the nutritional part), and was likely consumed by North American colonials. The text suggests it was used as a breakfast cereal with milk and maple sugar. Only later did popcorn become a snack food. • Several major historical changes are associated with corn cultivation and transport of corn-based products: • expansion westward in the U.S. and Canada • an underlying reason for the Louisiana purchase • Canals, Railroads, roads

22. Maize is low in tryptophan, lysine and other essential nutrients (Niacin; Vitamin B12), therefore: • Diets heavily dependent on corn show evidence of ‘Kwashiorkor’ • Nutritional problems occur with a corn-only diet – vitamin deficiency causes pellagra. However, native American processing of corn with lime frees vitamins, and the disease rarely appears. In Europe, without lime processing, pellagra was first noticed in 1730 and the nutritional basis of the disease was not resolved until 1930s • 3. There has been a recent emphasis on fortifying amino acid content using both ‘traditional’ breeding approaches (selection of high lysine corn) and GMO (genetically modified organisms, more controversial).