RESUMEN
A study to obtain information on early segregating generations of an intervarietal cross 'WG 357' X 'Tobari 66' in spring wheat on the genetics of days to heading, plant height, ear length and spikelets per spike was conducted. 'WG 357' has amber, hard and lustrous grains and is a well adapted high yielding variety of North India whereas 'Tobari 66' is red grained introduction from CIMMYT.The parental F1, F2, B1, B2, biparentals, F3 (parents of biparentals), F3 bulk and F4 bulk generations were studied in order to provide analysis of generations means (Mather 1949; Hayman 1958) and variance component analysis (Kearsay 1965; Perkins and Jinks 1970).There were highly significant differences among the generations for all the characters studied. There were significant differences among the F3 lines as well as among the biparental progenies. Only in case of ear length was the contrast between the two also significant. The mean value of most of the generations arising from the cross fell between the parental range.The three-parameter model failed to account for the variation in generation means in the case of days to heading. This character was concluded to be influenced by linkage and higher order interactions. For the other characters the three parameter model was adequate. For all characters, additive gene effects were most important as compared to dominance gene effects.The analysis of gene action as provided by the generation variance indicated that additive variance was much more pronounced as compared to dominance variance. The heritability was high for days to heading (71 per cent for narrow sense and 80 per cent in broad sense) and plant height (62 and 93 per cent in narrow and broad sense respectively.The implications of the results in breeding programmes have been discussed.