Agricultural Uses
Rice (Oryza sativa) is probably the single most consumed
food grain in the world. It has been in existence for the
last 7000 years. Rice, an annual, is multi-stalked plant which grows to around a meter. The grains,
borne by a panicle, are surrounded by bracts. Air
columns in the stalk enable the diffusion of air through
the stem down to the roots. The process of threshing and
winnowing, followed by milling and polishing, converts
the harvest into the marketable product that people
commonly consume.
Since rice is the native of South-East Asia, it is best
suited to a watery ecosystem and is mostly grown in
flooded fields. Rice plants are able to resist decay even
while they remain submerged for long periods. This
happens by the help of the stems that are both elongated
and perforated, helping the plants to photosynthesize and
transport oxygen to the roots.
Over thousands of years of its existence, rice has
adapted itself to survive different situations, like drought,
floods, nutrient stress, etc. Rice is categorized according
to the environment in which it grows. Thus, rice is grown
in rainfed lowland, deepwater, tidal wetland, rainfed
upland and irrigated land areas. Upland rice is the rice
cultivated on lands without ponding
Rice is grown on 155 million hectares of land across
100 countries. Consumption of rice increases by an
average of 2 % every year. Asia produces 92 % of the total
rice, accounting for 90% of the harvested area.
However, there is still a shortage of the grain in the
world. While Australia has achieved the highest rice
yield (10 tons per hectare). Asia manages only 3.9 tons
per hectare. One of the reasons is that in Asia, there are
about 250 million tiny land holdings dedicated to rice,
making large scale agricultural practices difficult to
adopt.
Rice is a good source of thiamine and niacin (both
Vitamin B). It also provides iron, phosphorus and
magnesium. It has higher levels of amino acid and lysine
compared to other cereal grains.
Rice is also categorized on the basis of the nature and
treatment of the grain, that is, size, variety and
processing. Accordingly, there is long grain rice,
medium grain rice, short grain rice (according to size)
Arborio, jasmine, black rice, fermented red rice,
parboiled rice, aromatic rice, glutinous rice, etc.
(according to variety) and enriched rice, converted rice,
instant white rice, etc. (based on processing methods).
The nutrient value decreases when processes like
mechanized milling and polishing are used. The
unprocessed rice is called brown rice (the dehulled whole grain) which is more nutritious compared to white rice
which is refined and processed.
