Speciality corn types with reference to quality protein Maize (Zea mays L.) -A review

Ceareals are the major source of nutrition for one third of the world's population espacially in developing countries. The three major cereals rice, wheat and maize constitute about 85% of total global cereal production amounting to about 200 million tonnes of protein harvest annually at an average of 10% protein content, out of which a sizeable proportion goes into human consumption. Corn is one of the most diverse grain crop found in nature. Selection pressure by both humans and nature has resulted in various types of corn generally classified by characteristics of their kernel endosperm (tissue surrounding the embryo that provides food for the seed's growth). The most common types of corn include dent corn, sweet corn, pop corn, high lysine corn (QPM), high oil corn, waxy corn, high amylose corn, ornamental corn and corncob corns. The physical appearance of each kernel type is determined by its pattern of endosperm composition as well as quantity and quality of endosperm. At global level, maize accounts for 15% of proteins and 20% of calories in world food diet. Breeding for improved protein quality in maize began in the mid-1960s with the discovery of mutants such as opaque-2, that produce enhanced levels of lysine and tryptophan, the two amino acids deficient in maize endosperm proteins. Quality protein maize has widely been adopted for cultivation in the developing world to fight protein malnutrition. Maize is also important component of livestock feed espacially in developed nations where, 78% of total maize production goes into livestock feed. Therefore, breeding strategies aimed at improving the protein profile of maize will go a long way in reducing prevalence and persistence of malnutrition in developing world.