Location of Genes for Dwarfing in the Wheat Variety Sonora 64

Monosomic F₂ analysis from crosses between Cadet monosomic lines and Sonora 64 have shown that fifteen chromosomes are involved in dwarfing the culm to different degrees. Two chromosomes (5B and 7D) of Sonora 64 have been found to have no significant effect on culm length. All the chromosomes belonging to the homeologous group 2, 3 and 4 and some belonging to group 1, 5 and 7 were found to have effect in dwarfing. Amongst these chromosomes, members of group 2 and 3 were more homogeneous in their efiect within a group, while members of 1, 4, 5 and 7 groups were heterogeneous in effect. There have been found at least two chromosomes in each genome (2A and 4A, 1B and 2B, 2D and 5D) reducing the culm length most. It has been assumed, that the fifteen chromosomes of Sonora 64 reduce the culm length to different degrees, show the effect of the major and minor genes for dwarfing located on them. It has been tentatively suggested that the two major dwarfing genes of Sonora 64 may possibly be located on 1B, 2A, 2B, 2D, 4A or 5D and most probably on 1B and 5D.

Disomic F₃ lines have transgressed both the dwarf and tall parents. Importance of the dwarfer lines in the future breeding programme has been pointed out.