Project Background
Food security is one of the most pressing issues for humanity. Soil salinisation is a pervasive issue in agriculture that will increase with climate change globally. Crops growing in fields with saline soils or that can only be irrigated with brackish water experience a combination of osmotic, ionic and ion-specific (Na+, Cl-) stresses that increase gradually during plant development and impair plant physiology and development. Decades of research have unravelled the mechanisms that are involved in crop salt stress tolerance. In spite of this, attempts to improve crop resilience to salinity by modifying genes involved in salt stress response have not met expectations.
Some of the difficulties in improving crop yield stability under abiotic stress have been blamed on faulty experimental designs where abiotic stress treatments have little relevance to natural scenarios, yet direct comparisons between realistic and unrealistic stress treatments are rare. While it is recognised that the sudden introduction of high salinity in the root environment generates an osmotic shock unlikely to occur in field conditions where gradual salt accumulation engenders a different stress, the consequences of acute osmotic shock on the outcome of long-term salt stress experiments are unknown. In many salt stress studies, plants are grown in an inert medium like sand so as to permit control of the rhizosphere salt concentrations to provide a homogenous stress; however, soil is naturally heterogeneous and thus salt effects in soils will be as well. Additionally, root architecture of many plants differs in sand and soil, it is thus necessary to know to what extent the responses of crops to salt stress in sand differ to those in soil. The majority of salt stress treatments thus far rely on the application of a solution of sodium chloride. Although these are the main ions that accumulate in the soil during salt stress, other ions are present in saline soils, brackish water and seawater that can alleviate the physiological effects of high sodium chloride concentrations. Accordingly, white clover responses to flooding with sodium chloride solutions were markedly different (and more lethal) than exposure to acute flooding with seawater or commercial marine aquarium salt solutions, owing to the other ions present. Other than that, the difference in crop plant response between natural salt stress and sodium chloride has not been investigated.
