Salinity induced differences in growth,ion distribution and partitioning in barley between the cultivar Maythorpe and its derived mutant Golden Promise

Dry matter changes and ion partitioning in two near isogenic barley cultivars Maythorpe (relatively salt sensitive) and Golden Promise (relatively salt tolerant) were studied in response to increasing salinity. Although the growth of both cultivars was significantly reduced by exposure to NaCl, the effect was greater in Maythorpe, whilst Golden Promise maintained an increased ratio of young to old leaf blade. Golden Promise maintained significantly lower Na⁺ concentrations in young expanding tissues compared with Maythorpe. Partitioning of Cl^– was evident in that both varieties maintained lower Cl^– concentrations in mesophyll than in epidermal cells. Golden Promise maintained higher K⁺/Na⁺ and Ca²⁺/Na⁺ ratios in young leaf blade and young sheath tissues than Maythorpe when exposed to salt. Differences in ion partitioning and the maintenance of higher K⁺ and Ca²⁺ to Na⁺ ratios, especially in young growing and recently expanded tissues, would appear to be important mechanisms contributing to the improved salt tolerance of Golden Promise.