Assessment of salinity tolerance based upon seedling root growth response functions in maize (Zea mays L.)

Root growth response of 10-days-old seedlings of 100 maize accessions at, 0 mM, 60 mM, 80 mM and 150 mM NaCl concentration was assessed in solution culture. The non-linear least square method was used to quantify the salt tolerance of maize accessions. The estimated salinity threshold, Ct, the NaCl concentration at which root growth starts to decrease, C0, and C50, the concentrations at which roots stop growing and 50% of its control value revealed considerable differences between the accessions. No general consistency for tolerance was, however, found between the estimates of Ct and C50. Different genetic systems appeared to be involved in controlling the inheritance of Ct and C50. Both Ct and C50 appeared to quantify accession tolerance, and the expression of root growth as a function of NaCl concentrations provides a useful guideline for salt tolerance. Estimates of broad sense heritability for relative root length were moderate in size (0.62 to 0.82), suggesting the scope for enhancing salt tolerance in maize through selection and breeding.