Maintenance of high K+ concentrations in salt-tolerant genotypes was observed only among plants grown in soil at ECe 7.2 dS m-1 in Experiment 2, which may be one of the mechanisms underlying their higher salt tolerance (Table 4). However, for plants grown in hydroponics, at a soil ECe ∼15.3 dS m−1 and in the field there was no significant relationship between salt tolerance and/or grain yield and the shoot concentrations of K+. The ratio of K+:Na+ has been associated with salt tolerance , however, in the current study, the significant positive correlation between grain yield and K+:Na+ appears to be due to the genotypic variation in shoot Na+ concentration rather than maintenance of high shoot K+ concentration: there was a negative correlation between salt tolerance and Na+ and no significant relationship with K+.