In the cross involving chromosome 6A of UP 301 all the plants had brown awns which confirmed presence of independently dominant gene A for brown coloured awns on chromosome 6A of UP 301.
The F2 population monosomic for chromosome 2B showed a good fit for 60 brown : 4 black awns (x2=2.85) indicating the presence of a dominant complementary gene, B on chromosome 2B of UP 301.
The critical population monosomic for chromosome 1D of UP 301 was found to agree with 3 brown : 1 black awns ratio (x2=0.25) which proved the presence of a recessive allele of the complementary gene C for brown coloured awns.
The other two populations viz., 3B and 5B which were critical at 5 per cent level of probability are thought to carry minor modifying factors which cause slight deviation in the phenotypic frequency.
As no reports are available on the cytogenetic analysis of awn colour, the present finding is only tentative. However, an indirect evidence can be derived. SIKKA et al. (1961) found linkage between genes controlling glume pubescence and awn colour. In the present investigation a basic gene for glabrous glume and an independent dominant gene for brown awns were found to be located on chromosome 6A of UP 301 which is an indication of linkage between the genes for glume pubescence and awn colour.
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