Salt tolerance and ionic relations of wheat as affected by individual chromosomes of salt-tolerant Lophopyrum elongatum

Bread wheat cv. Chinese Spring (CS), an amphiploid from a cross between CS and salt-tolerant Lophopyrum (= Agropyron) elongatum (Host) Löve, 19 of 21 possible disomic substitution lines of L. elongatum chromosomes for CS homoeologues, and a check cultivar, PI 178704, were grown in a replicated field trial under two levels of salinity and control conditions. Under salinity, the amphiploid greatly outperformed CS in grain yield, biomass, and other characters, indicating that it is more salt tolerant than CS. Of the seven L. elongatum chromosomes, six increased salt tolerance in disomic substitution lines; the most dramatic increase was conferred by chromosome 3E. Increased salt tolerance of the amphiploid was associated with the exclusion of Na+ and Cl− and inclusion of K+ as well as retranslocation of K+. Lophopyrum chromosomes controlling these physiological characters were identified. Some of the chromosomes had multiple effects, where as others affected only a specific character. The largest effects were associated with chromosome 3E. In addition, several wheat chromosomes controlled the exclusion or inclusion of these ions; the most notable effects were by chromosome 4D. Salt tolerance correlated negatively with Na+ and positively with K+ concentration in the flag leaf and with the K+/Na+ ratios. The relationships were strong enough to be exploited as selection tools in the breeding of salt-tolerant wheat cultivars.Key words: salt tolerance, wheat, Lophopyrum elongatum.