Progress in Plant Salinity Resistance Research: Need for an Integrative Paradigm

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Abstract
SUMMARY Population pressure, shortage of good arable land and good quality waters are forcing crop production into more marginal environments facing abiotic stresses (drought and salinity) and thereby limiting the adaptation and productivity of staple food crops. The situation is assuming serious proportion, as almost half of the existing irrigation system of the world is under the influence of secondary salinity, sodicity or waterlogging. Therefore, to maintain productivity of existing arable land, the sustainability of the agricultural and irrigation systems that has been generated at a huge cost, is more important than immediate increases in yield. Much work done in the last century in several countries has increased our understanding of the genetics and physiology of salt tolerance of plants. Crop responses to salt stress are made up of a number of complex and interrelated, morphological, physiological, and biochemical processes. However, we still do not have a complete understanding of the underlying mechanisms of salt tolerance. The multigenic, quantitative nature of salt tolerance imposes several limitations on the efforts to improve salt tolerance of plants. The biological approach to tackle problems of salinity has its critics as well as advocates. Identification and development of crops and their cultivars with improved salt tolerance has been the key to improve productivity. Efforts in this direction using traditional methods of plant breeding and modern tools of biotechnology have led to the development and release of many cultivars with improved salt tolerance at the global level. Many of these superior cultivars have yet to prove their worth in actual stress situations. Integrative approaches in this direction, including the frontier areas of plant molecular biology have been discussed. In view of the enormity of the situation and immense challenges involved, efforts in this direction have to be more focused and multidisciplinary in approach. This should receive much higher priority and resources from scientists, administrators, and policy makers.