Salt tolerance improvement in some wheat cultivars after application of in vitro selection pressure

Somatic embryogenesis through callus initiation has been quantified under salt stress conditions for 8 wheat cultivars currently cultivated in Morocco. The cultivars were classed according to the mean number of somatic embryos formed per immature embryo half and regenerated plants per 100 explants under saline conditions. Regenerated plants from control callus (R0-0) and callus initiated on 10 g l(-1) NaCl (R0-10) did not show significant differences concerning plant height, spike length and grain number per ear but, the R0-10 plants remained less developed than parent plants. When watered with a solution containing more than 20 g l(-1) NaCl, the seeds of cultivar Te derived from R0-10 regenerated plants exhibited the best elongation of roots and coleoptiles. Furthermore, a chlorophyll fluorescence test showed a clear improvement in salt tolerance of R1-10 plants at four to five-leaf stage, compared to R1-0 plants. It is concluded that plant regeneration from callus initiated on high NaCl levels may be a valid method of selection for salt tolerance.