A practical approach to improving salinity tolerance in winter cereals

Abstract

Tolerance of crop species, such as wheat and barley to salt stress is a complex trait and is considerably influenced by the environment. There is a paucity of information on the genetics and physiological basis of salt tolerance. The evaluation of germplasm for salinity tolerance under field conditions is complicated by the heterogeneity in salt concentration at different depths in the soil, time and space, and by the differential response of plants to salt stress at different stages of growth. Usually, empirical methods are used to screen germplasm lines for salt tolerance. Although salt-tolerant lines have been identified in screening experiments, wheat and barley cultivars have rarely been developed on the basis of their tolerance to salt stress. Development of broad-based germplasm pools by intercrossing salt-tolerant lines of diverse origin followed by mass propagation under highly saline conditions is a realistic approach. Maximum benefits from such salt-tolerant germplasm pools could be derived by maintaining them in a dynamic state of genetic heterogeneity. Planned introgression from promising wild relatives should be allowed to enhance genetic diversity in these salt-tolerant germplasm pools. These enriched and dynamic populations would then form the basic materials in breeding for salt tolerance. Genetic improvement of cereal crops for salt tolerance should be an integrated interdisciplinary approach, involving molecular and whole plant geneticists and stress physiologists. Current developments in elucidating genetic basis of salt-tolerance are reviewed.