Introduction

"Rice is the primary staple food for more than half the world's population, and Asia, Sub-Saharan Africa, and South America are the largest consuming regions. The bulk of global rice is classified as Oryza sativa, a plant species that is believed to have originated in Asia from the Graminaceae (grass) family. Although rice is produced over vast areas of the world, the physical requirements for growing it are limited to certain areas. Economically sound production typically requires high daytime temperatures and cooler nights during the growing season, a plentiful supply of water applied as needed, a smooth land surface to facilitate uniform flooding and drainage, and a subsoil hard-pan that inhibits percolation (downward movement of water through the rice bed). Four major types of rice are produced and traded worldwide (table 1)." - USDA: Rice Sector at a Glance