Genetic Studies in Tetraploid Wheat V

Inheritance of waxybloom, early flowering and plant height has been studied in six intra-specific and five inter-specific combinations of tetraploid wheats. Waxiness was found to be recessive in all the combinations except in two inter-specific crosses (T. dicoccum ×T. durum and T. durum ×T. pyramidale). In all the combinations waxiness was controlled by a single pair of alleles except in T. dicoccum—KDH × T. durum—Nurshit where two pairs of dominant alleles were responsible for the expression of this character. Arbitrary classification of earliness in flowering (60±3 days as early and rese as late) suggested this character to be monogenically controlled in NI-146 × Townse and T. durum ×T. pyramidale and digenic control was observed in two T. durum crosses. By adopting similar classification for plant height, operation of duplicate dominant genes has been noticed. In these studies the dwarf parents used are the homozygous inter- specific derivatives of T. dicoccum ×T. turgidum and T. pyramidale ×T. dicoccum combinations breeding true for dwarmess. These are different sources for dwarfness than the usual T. durum—Norin-10 widely used in the breeding programme.

Overall comparison of these results revealed constancy in the genetic constitution, shifts from monogenic to digenic control and reversal of dominance.