The Importance Of Rice

Rice (Oryza spices) is a monocotyledonous plant belonging to the family Granineae and subfamily Oryzoidea. It is cultivated under diverse eco-geographical conditions in various tropical and subtropical countries1. Due to its importance as a food crop, rice is being planted on approximately 11% of the Earth’s cultivated land area2. It is the grain with the third highest production globally after sugarcane and maize (FAOSTAT, 2012). Oryza sativa and Oryza glaberrima are the only two cultivated species of rice while the other species are wild. Oryza sativa is commonly grown in Asia, North and South America, Europe and Africa. Oryza glaberrima is highly grown in West African but due to higher yields of O.sativa and O. glaberrima-sativa varieties;

Glutinous or waxy rice in which endosperm starch lacks or has very little amylose content consists mainly of amylopectin starch4. The ratio of amylose to amylopectin has a major effect on the physical properties of starch. When cooked, the semi-crystalline structure of rice starch is disrupted thus transforming the starch into a softer, edible, and gel-like material5. Generally, the amylose content of milled rice is classified into five classes: waxy (0–2%), very low amylose (3–9%), low amylose (10–19%), intermediate amylose (20–24%) and high amylose (above 24%)6. The cooking temperature at which water is absorbed and the endosperm starch granule swell irreversibly with subsequent loss of crystalline structure is referred to as gelatinization temperature (GT)7. Gelatinization temperature is an important component of rice cooking quality. Rice grain with low gelatinization temperature takes shorter cooking times leading to significant

The high genetic variation within the sample populations could be due to increased gene flow or mutations of a number of repeats of a given genotype for a given SSR. In addition, natural selection mechanism could be another source of this high genetic variation within the rice genotypes studied. On the other hand, the relatively low genetic variation among these rice genotypes could be attributed by sharing of same SSR profiles among themselves. The low genetic variation among these genotypes could explain the probability of sharing a common ancestry despite the fact that they are grown in different countries. Similar huge differences in percentage variation between and among a group of rice genotypes studied using SSR markers were reported