Breeding for salinity tolerance

Abstract

Soil salinity is a major factor adversely affecting crop yields worldwide. It is estimated that worldwide about 1 billion ha of land is affected by salinity. In addition, salinity problem is increasing at a rate of about 10% annually worldwide. Salinity can cause a combination of complex interactions that affect plant metabolism, susceptibility to injury or internal nutrient requirement. The negative interactions of salts with crop plants may reduce growth and consequently nutrient use efficiency. Management practices which can be adopted to reduce negative effects of salts on plant growth includes leaching salts from soil profile, use of amendments such as gypsum, and use of farmyard manners. However, use of salt-tolerant crop species or genotypes within species is a very attractive strategy to reduce cost of salt reclamation and environmental pollution. Although salt tolerance is relatively low in most crop species, it is encouraging that genetic variability exists not only among species but also among genotypes of same species. Salt-tolerant crop species are barley, cotton, oats, rye, triticale, sugar beet, guar, and canola or rapseed. Plant resistance responses include both salt avoidance (selective uptake or exclusion mechanisms and salt secretion, such as through salt glands) and salt tolerance (osmotic adjustment to maintain turgor pressure, tissue tolerance to specific toxic ions, e.g., Na and Cl, and tissue dehydration tolerance).