Rice grain

Rice is the seed of the plants Oryza sativa (Asian rice) or Oryza glaberrima (African rice). The name wild rice is usually used for species of the genera Zizania and Porteresia, both wild and domesticated, although the term may also be used for primitive or uncultivated varieties of Oryza.

History
As a cereal grain, it was the most widely consumed staple food for a large part of Earth’s human population, especially in Asia. It was the agricultural commodity with the third-highest worldwide production, after sugarcane and maize, before Earth’s WWIII. Since a large portion of maize crops were grown for purposes other than human consumption, rice was the most important grain with regard to human nutrition and caloric intake, providing more than one fifth of the calories consumed by humans. There are many varieties of rice and culinary preferences tend to vary regionally. In some areas, there is a preference for softer and stickier varieties.

Genetic evidence has shown that rice originates from a single domestication 8,200–13,500 years ago in the Pearl River valley region of China. Previously, archaeological evidence had suggested that rice was domesticated in the Yangtze River valley region in China. From East Asia, rice was spread to Southeast and South Asia. Rice was introduced to Europe through Western Asia, and to the Americas through European colonization.

Cultivation
 Rice is normally grown as an annual plant, although in tropical areas it can survive as a perennial and can produce a crop for up to 30 years. The rice plant can grow to 1–1.8 m tall, occasionally more depending on the variety and soil fertility. It has long, slender leaves (50–100 cm long and 2–2.5 cm broad). The small wind-pollinated flowers are produced in a branched arching to pendulous inflorescence 30–50 cm long. The edible seed is a grain 5–12 mm long and 2–3 mm thick.

 Rice cultivation is well-suited to countries and regions with low labor costs and high rainfall, as it is labor-intensive to cultivate and requires ample water. However, rice can be grown practically anywhere, even on a steep hill or mountain area with the use of water-controlling terrace systems. Although its parent species are native to Asia and certain parts of Africa, centuries of trade and exportation have made it commonplace in many cultures worldwide.

 The traditional method for cultivating rice is flooding the fields while, or after, setting the young seedlings. This simple method requires sound planning and servicing of the water damming and channeling, but reduces the growth of less robust weed and pest plants that have no submerged growth state, and deters vermin. While flooding is not mandatory for the cultivation of rice, all other methods of irrigation require higher effort in weed and pest control during growth periods and a different approach for fertilizing the soil.

 Modern Rice Use

 Rice is the third most grown Terran grain (behind wheat and maize). It is the most grown and consumed grain on worlds settled by humans from Earth’s Asia region.