How much sodium accumulation is necessary for salt tolerance in subspecies of the halophyte Atriplex canescens?

Accessions of Triticum tauschii (Coss.) Schmal. (D genome donor to hexaploid wheat) vary in salt tolerance and in the rate that Na(+) accumulates in leaves. The aim of this study was to determine whether these differences in salt tolerance and leaf Na(+) concentration would be expressed in hexaploid wheat. Synthetic hexaploids were produced from five T. tauschii accessions varying in salt tolerance and two salt-sensitive T. turgidum cultivars. The degree of salt tolerance of the hexaploids was evaluated as the grain yield per plant in 150 mol m(-3) NaCl relative to grain yield in 1 mol m(-3) NaCl (control). Sodium concentration in leaf 5 was measured after the leaf was fully expanded. The salt tolerance of the genotypes correlated negatively with the concentration of Na(+) in leaf 5. The salt tolerance of the synthetic hexaploids was greater than the tetraploid parents primarily due to the maintenance of kernel weight under saline conditions. Synthetic hexaploids varied in salt tolerance with the source of their D genome which demonstrates that genes for salt tolerance from the diploid are expressed at the hexaploid level. Show more