Strategies for increasing the yield potential of cereals: case of rice as an example

Rice is the most important food crop. Worldwide, more than 3.5 billion people depend upon rice for more than 20% of their calories. Global rice demand is estimated to rise from 676 million tons in 2010 to 763 million tons in 2020 and to further increase to 852 million tons in 2035. This is an overall increase of 176 million tons in the next 25 years. To meet this challenge rice production on existing land must be increased. Grain production is largely influenced by the yield potential of rice varieties. Therefore, improvement in the yield potential of rice is the major strategy to increase world rice production. Various strategies to increase the yield potential include; (1) conventional hybridization and selection, (2) ideotype breeding, (3) hybrid breeding, (4) exploitation of wild species germplasm, (5) enhancement of photosynthesis, (6) genomic approaches and (7) physiological approaches. Rice has become a model plant for genetics and breeding research. Advances in molecular biology and genomics, proteomics and metabolics have opened new avenues to apply innovative approaches to rice breeding. Molecular-assisted selection (MAS) has become an integral component of germplasm improvement. A large number of genes/QTLs for various traits have been tagged with molecular markers to apply MAS for trait improvement. Genome sequence data have become an important source for detecting allelic variation. It is now possible to precisely understand the role of epigenetic changes in gene expression, thus understanding the stability of various stresses under changing environments. All these advances when integrated with conventional breeding will result in designer rice varieties to meet the challenges of rice food security in 21th century.