Salinity stress negatively impacts agricultural yield throughout the world affecting plant production, whether it is for subsistence or economic gain. Salinity threat to global agriculture is also aggravating by becoming more prevalent with the intensity of land use increase worldwide (Meloni et al., 2003; Rangasamy, 2006).

Salinity often reduces shoot growth more than root growth (Läuchli and Epstein, 1990). However, when plants are growing in high salt concentrations, an adequate sequestration of ions in the vacuole can become a limiting factor, especially in the case of glycophytes. In this scenario, undue amounts of Na⁺ accumulated by plants in their cytosol, disrupt many aspects of cellular physiology. Antagonistic effects on nutrient uptake may occur, causing deficiencies, particularly of K⁺ and Ca²⁺ under conditions of excessive Na⁺ content (Shahzad et al., 2012). For example, the physiochemical similarities between Na⁺ and K⁺ lead to competition at transport and catalytic sites that normally bind the essential cation K⁺ and maintaining a high cytosolic K⁺/Na⁺ ratio is believed to improve salt resistance (Maathuis and Amtmann, 1999; Zhu, 2001).  In our project combined treatments of K⁺ and Na⁺ have been added to examine physiological differences with varying salinity levels.

It is expected that exposure of plants to salinity will also result in a wide range of metabolic responses. Intracellular concentration of a range of soluble, neutral organic compounds that are collectively titled as ‘compatible solutes’ are the well explained metabolic changes (Bohnert et al., 1995; Bohnert and Shen, 1998). However, compatible solutes are non-toxic and do not disturb cellular functions even when present in high concentrations (Yancey, 2005). It is believed that the increased concentrations of compatible solutes in the cytoplasm can contribute to reduce the water potential in the cytoplasm by balancing the decreased water potential associated with Na⁺ accumulation in the vacuoles and the extracellular volume (Widodo et al., 2009).

In summary current project focused on metabolic changes in the pea leaves which can increase our physiological knowledge in understanding the salinity tolerance. Also, how combined treatments of K⁺ and Na⁺ can affect the change in leaf metabolites in two salt tolerant (Climax) and salt sensitive (Meteor) cultivars of pea.