| Spring wheat breeding and the transfer of economic
characters from related species and genera Fred C. ELLIOTT Department of Agronomy, Washington State College, Pullman Washington, U.S.A. Work on the Translocation of bunt resistance and in separate material the translocation of combined leaf and stem rust resistance from tall wheatgrass, Agropyron elongatum 2n=70 to hexaploid wheats, is going forward. The dominant bunt resistance of tall wheatgrass is carried on one extra chromosome in resistant derivatives obtained by continuous backcrossing to a susceptible winter variety. Through both irradiation and continuous backcrossing a number of 42 chromosome resistant plants have been obtained. Progeny tests of these are being made this year. Both 42 and 43 chromosome X4 plants have also been obtained from an X3 progeny row homozygous for resistance to the various biotypes of 15 b and other stem and leaf rust races in the rust nursery of the Dominion Cereal Laboratory at Winnipeg in the summer of 1955. This material arose from an 18.000 gamma X-ray treatment of the F0 Seed (2n=49) obtained from the cross between a rust-resistant 56 chromosome wheatgrass derivative and a susceptible spring variety. During the year a number of octaploid wheat-like materials have been assembled for intercrossing and irradiation in an attempt to develop new wheat types at this chromosome level. |