Genetic Diversity of Rice Grain Quality

Abstract

Rice (Oryza spp.) is one of the most important food crops in the world, being planted on almost 11% of the Earth’s cultivated land area over a wide number of ecosystems (Khush, 2005; Maclean et al., 2002). Two species, Oryza sativa and O. glaberrima, are cultivated while other species are wild. Human selection and environmental factors have contributed to the genetic diversity in rice, particularly in O. sativa cultivars (Maclean et al., 2002). A significant amount of this genetic diversity is housed in rice gene banks around the world, with a copy also conserved in the snowy depths of Svalbard, Norway. The diversity of rice offers a valuable resource to understand grain quality and how different agronomic backgrounds alter those traits. Rice is consumed mainly as milled, white grains or as brown grains (unpolished), and also as ingredients in food products. The cooking and sensory properties of a variety are key components that affect its acceptability to consumers (Cramer et al., 1993). Consumer preferences shift from low-quality to high-quality rice with increased income and market liberalisation (Cramer et al., 1993; Dawe & Slayton, 2004). Improvements in post-harvest technologies have also contributed to this shift in consumer preference by decreasing the price difference between lowand high-quality rice (Dawe & Slayton, 2004).