INHERITANCE OF THE TYPE OF SOLID STEM IN GOLDEN BALL (TRITICUM DURUM). III. THE EFFECT OF SELECTION FOR SOLID STEM BEYOND F5 IN HEXAPLOID SEGREGATES OF THE HYBRID RESCUE (T. AESTIVUM) X GOLDEN BALL

Abstract

Introduction .An attempt to transfer the extreme solidness of the top c u l ~ n internode of Golden Ball (Triticz~v~11 ~ Z ~ I Z L W I Desf.) to a hexaploid wheat by crossing Golden Ball u,itll Rescue ( T . aestivrnll I,. emend Thell.), \vhich has a less solid top internode, but more solid lo\ver internodes, was onlv partially successful. Apparently, chromosome 3D (XVI) from the D genome of ~ e s c ; e prevented full expression of the Golden Ball gene(s) for a solid top internode (I,arson, 1959a and b). T h e degrce of solidness of the lower internodes nras inherited independently of the number of D-genome chromosomes present. Three 12-chromosome plants were found in the F, test (Larson, 1959b). 'Their top internodes were more solid than those of Rescue but less solid than those of Golden Ball. They differed from one another in degree of solidness of both top and lower internodes. Although it seemed unliltely that further selection could produce a hybrid \I-ith a top internode as solid asvthat of Golden Ball, it was considered possible that accunlulation of nlinor genes could increase the solidness, provided that the I;, hvbrids were still heterozygous at one or more loci for solid stem. T o test this' possibility, selections made for increased and for decreased solidness in the F,, were tested in the F;. Selections for increased solidness only were made in the F7 and tested in the F.. This paper deals \vith the segregat io~~ for stem so,lidness in these lines.