USE OF WINTER-WHEAT X TRITICUM-TAUSCHII BACKCROSS POPULATIONS FOR GERMPLASM EVALUATION

The wild diploid goatgrass, Triticum tauschii (Coss.) Schmal., is an i mportant source of genes for resistance to both diseases and insects i n common wheat (Triticum aestivum L.) We have evaluated grain yield, k ernel weight, protein concentration, and kernel hardness of 641 BC2 F- 1-derived families from direct crosses involving four T. aestivum cult ivars and 13 T. tauschii accessions over 2 years and at two Kansas, US A, locations. On average, T. tauschii germplasm depressed grain yield and increased protein concentration, whereas kernel weight was affecte d either positively or negatively, depending on the T. tauschii parent . Three T. tauschii parents produced a large proportion of families wi th very soft endosperm. Some variation among progeny of different T. t auschii parents resulted from the segregation of genes for resistance to leaf rust (caused by Puccinia recondita Rob. ex Desm.). This study confirmed that random BC2-derived families can be used to evaluate the effects of T. tauschii genes in the field. This methodology, although laborious, can provide useful information which is not obtainable by the screening of T. tauschii accessions themselves.