Introduction Of Rice Essay

1. Introduction to Rice
1.1 Rice as an important agricultural crop.

Rice which is a monocotyledonous angiosperm, belongs to the family Poaceae, genus Oryza, is the most important staple food crop of the world and serves as the main source of calories consumed by human and occupies almost one-fifth of the total land area covered under cereals. Rice was originated about 14 million years ago in South Asian area and Philippines. Now it has evolved and diversified into wild Oryza species which contains more than 20 species. Rice was originally cultivated in tropical Asia, the oldest record dating 5000 years BC, but then extended also to temperate regions.(Sharma and Singh, 2013).

Oryza sativa and Oryza glaberrima are the two cultivated species where Oryza sativa is grown all over the world and Oryza glaberrima is cultivated in West Africa (Londo et al., 2006).
Asian rice was first domesticated from Oryza rufipogon in China and now has spread all over the Asia and worldwide there are more than 40,000 different varieties of O.sativa, which has four major categories indica, japonica, aromatic and

Asia accounts for over 91% of the world's production of rice and the main producers are China and India (figure 1-A)

Figure 1: A- Average prodution of rice,paddy by region, 1996-2016/ B- Production yeild and area harvested quantities of rice, paddy in world, 1996-2006
(Source: FAOSTAT)

Area harvested rice, paddy and the production of rice increases with time due to increasing population and high demand (figure 1-B). Global rice production more than tripled between 1961 and 2010, with a compound growth rate of 2.24% per year (2.21% in rice- producing Asia)
1.3.2 Sri Lankan Rice