What do rice grains grow on

Plants · Research · Agriculture · Food

Panicles of rice plants (above), rice fields on Bali (below)

Photo (above): USDA / ARS
Photo (below): ASchick01 / pixelio.de

Scientific name:Oryza sativa

Family: Sweet grasses (Poaceae)

Growth habit: The annual grass is up to 1.5 meters high. Rice plants form a main stalk and several secondary stems. The hollow stalks are interrupted by about twenty nodes on which leaves grow. These are one to two inches wide and up to sixty inches long. The inflorescence consists of thirty to 200 so-called spikelets, which are arranged in a panicle. Each spikelet encloses a hermaphrodite flower between a lemma and two glumes.

Rice plants have a ventilation fabric (Aerenchyma) in their roots. This allows them to grow on flooded soils.

Fruit: The fruit, the grain of rice, emerges from a fertilized flower. The fruit is botanically called the caryopsis among the grasses. Typical of this type of fruit is the fusing of the pericarp and the seed coat.

Propagation: In all types of rice, it is mainly self-fertilization that takes place. Cross-fertilization only occurs in about four percent of cases.

Outcrossing: Since self-fertilization predominates in rice, types of rice do not cross with each other very much. Basically, in areas where both cultivated and wild species grow, cultivated rice is released into the wild and various types of rice are hybridized. Wild species are more likely to cross with related species than cultivated rice varieties, as the latter have a greater tendency to self-pollinate and the lifespan of the pollen is shorter.

A species that is closely related to the cultural rice grows in the Eurasian region: Oryza oryzoides occurs on stream banks and in ditches.

Cultivation: Rice is not a water plant, but thanks to its ventilation system in the roots it can also grow in water. Therefore, both wet and dry rice cultivation is possible. Wet rice cultivation provides a constant supply of water and nutrients and prevents weeds from growing. In the case of dry rice cultivation, sufficient rainfall must fall during the growing season.

Rice is more adapted to site conditions than other types of grain. Therefore, the appropriate varieties must be bred for the different locations.

Origin: The genus Oryza is distributed worldwide with over twenty species in the tropics and subtropics. There are two types of culture: the one common in India and China Oryza sativa and the species native to West Africa O. glaberrima.

History: Finds in China, India and Thailand indicate that rice was cultivated until around 6,000 BC. Is backdated. In West Africa, too, was already 3,500 BC. Rice used as food. First, around 400 BC. BC, the spread of cultivated rice advanced to the regions of Iraq, Syria and Anatolia. Later the Moors spread rice cultivation in Europe. It was not until the 17th century that rice was grown in America and a century later in Australia.

The cultivation of rice can be considered one of the most important developments in human history. No other crop has fed as many people as rice for such a long period of time.