The Effect of Photoperiod Insensitivity on the Salt Tolerance of Amphiploids between Bread Wheat ( Triticum aestivum ) and Sand Couch Grass ( Thinopyrum bessarabicum )

The amphiploid between bread wheat cv. ‘Chinese Spring’ and sand couch grass Thinopyrum bessarabicum is tolerant of salinity stress under long daylengths, but is extremely late‐flowering and grows poorly under short daylength conditions. A newly synthesized amphiploid between the inter‐varietal single chromosome substitution line carrying chromosome 2D of the photoinsensitive cultivar ‘Ciano 67’ in a ‘Chinese Spring’ background and the same accession of Th. bessarabicum is photoinsensitive and is more tolerant of salinity stress under short daylengths, both in terms of decreased ionic uptake and in showing less damage to a range of agronomic characters. The genetic basis of this difference is probably due to the presence in this genotype of both Ppdl and to allelic differences between the Thinopyrum gametes involved in the two amphiploids.