Varietal improvement for abiotic stress tolerance in crop plants: Special reference to salinity in rice

Abstract

Abiotic stresses are both serious in magnitude and widespread in occurrence and thus pose major hurdles to attaining higher crop productivity. In rice, salinity follows only drought stress in both extent and gravity. Tapping the potential of large salt-affected areas to increase rice production would contribute to food security and alleviate poverty in unfavorable rice growing environments where most resource poor farmers live. However, this would necessitate the development of salt tolerant varieties and their widespread adoption by farmers. Past progress in breeding new salt-tolerant varieties has been slow due to obvious reasons. Moreover, abiotic stresses seldom occur singly and are more severe when occur jointly. Progress, however, is being made in developing new salt tolerant genotypes using both conventional and non-conventional breeding methodologies. Robust screening techniques have been developed, the screening criteria and selection pressure are well elucidated, the genetics of salt tolerance are better understood and suitable genetic donors have been identified. Component traits for salinity tolerance are being pyramided, and recurrent selection methods such as the diallel selective mating are being employed to increase the frequency of the desired alleles in breeding populations specifically designed for deployment in specific target environments. Modern tools and techniques such as molecular marker-assisted selection is also being integrated into conventional breeding programs to increase the pace and efficiency of the varietal development process. Proven mechanisms of international collaboration are being harnessed to generate reliable research outputs while novel technology development and promotion approaches are employed to improve adoption levels and impact of new varieties. Various examples on these developments are provided in this chapter. © 2010 Springer Science + Business Media B.V. All Rights Reserved.