| Frequency of albina plants was calculated on a total of 19039 seedlings - 16754 were
green and 2285 were albina seedlings. The overall frequency of albina was thus 12.00%. SEARS (1958) proposed a general model of breeding behaviour of monosomics. The frequencies proposed were disomics (21")=24%, monosomics (20"+ 1')=73% and nullisomics (20")=30%, when a normal monosomic plant is selfed. In the present data a very high frequency of nullisomics (12%), a marginal increase in disomics (27%) and significant reduction in the frequency of monosomics (61%) was observed as compared with the frequencies expected by SEARS (1958). The high frequency (12%) of nullisomics indicates that deficient male gamete functioned in about 18% of the cases as compared with a frequency of 4% that was observed, in general, by SEARS (1958). Functional female gametes were transmitted with a frequency of 67%, while this was 75% as reported by SEARS (loc, cit.). On the basis of this observation, the breeding behaviour of line monosomic for chromosome 3A in Pb. C 591 appears to be as proposed in Table 2. High transmission rate (18%) of deficient male gamete indicates lesser involvement of chromosome 3A in the post meiotic activities. Decrease in the transmission rate for the female gamete deficient for chromosome 3A suggests its greater involvement in prefertilization activities. Literature Cited SEARS, E.R. (1958). The aneuploids of common wheat. Proc. Ist Int. Wheat Genet. Symp. Winnipeg : 221-228. Singh, D. and B.C. Joshi (1979). Chlorophyll synthetic gene(s) in T. aestivum (var. Pb. C 591). Wheat Inf. Serv. 50: 45-46. |
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