Introduction:
Rice is an annual plant related to the family of gramincee and constitutes, with wheat and corn, one of the three basic cultivations of man. Its origins go far back in time that its habitat could be characterized in the ancient Gondwana super-continent, However, since the area still today has major varieties ranging from the region of Assam to northern India crossing the long chain of mountains of China, it is believed that the premature variety disappeared due to severe periodic drought, probably emerged after twelve thousand years or so along the southern slopes of the Himalayas. The main cultivated species called Oryza Asian Sativa (Oryza being the botanical name of the rice) Rice is closely involved in the culture as well as the food and the economy of many societies. Rice is an integral part of various cultures connected to various myths, for example Chinese myth, tells of rice being a gift. Throughout China today, tradition states that “the precious things of life are not pearls and jade but five grains”, of which rice is first.

Origin and Diffusion of Rice

The origins of rice have been debated for some time but the plant is of such antiquity that the precise time and place of its first development will perhaps never been known. It is certain, however, that the domestication of rice ranks as one of the most important developments in history, for its grain has fed more people over a longer period of time than has any other crop. The earliest agriculture was probably focused on plants that reproduced vegetative, but the seeds of easily shattering varieties of wild rice such as Oryza Fatua may have found their way to the gardens at an early date. The most likely places took place in the area of Korat or some sheltered basin area of northern Thailand, in the valley of Myanmars Shan Upland, in southwestern China in Assam. Cultivated rice belongs to two species, O, Sativa and Glaberrima. O, Sativa is by far the more widely utilized, complex one in its group. O, rufipogon is distinctive in South Asia, China, New Guinea, Australia and America. The O, Sativa began to diverge from the main forms about 15 million years ago. At the time, during the Miocene, the Asian portion of Gondwanaland collided with the Australian and New Guinean portion creating a land bridge across which O, Sativa migrates. Divergence between the South Asian and Chinese forms, the ancestors of what are commonly referred to today as indica and japonica (or sinica) types, is believed to have commenced 2 – 3 million years ago. The largest variety of such rice is found in zones of monsoon rainfall extending from eastern India through Myanmar, Thailand, Laos, and northern Vietnam and into southern China. In the course of the millennium the species of rice cultivated in Asia, Oryza Sativa, has differed in three subspecies. There are indica, from ancient finds in northern China, which go back as far as the V1 and V century a. C. the japonica, adapted in the moderate areas, last from China and Japan, and finally the Javanica, diffused in the islands of Indonesia. The three subspecies have maintained, through time, the respective dominant characteristics, that is: Long grain, thin and crystalline, short grain, with a thick pearl starch and sometimes glutinous, the japonica long and wide grain (similar to the varieties from Madagascar) The rice plant, grows, whatever the species in water, thanks to channels that enable the transportation of oxygen to the roots. In Italy, it is knowledge that the Greeks and Romans cultivated rice in the Mediterranean basin; this cultivation was then introduced to the Arabs during the 1, 11 and X111 century, in the regions of Puglie, Calabria and Sicily. Later rice found its habitat in northern Italy in the Po plain. The use of rice soon diffused especially in the areas of Milan, Novara and Vercelli.