| In order to discover the inner regulation of strong heterosis combination in hybrid wheat ,the systematic and deeply research in this paper is mainly about the partition of parent group , analysis of FI heterosis and use of F2, the result as follows:I. Using four group 11 parents and their 55 hybrids by completely diallel design (Griffing II mode), heterotic pattern in hybrid wheat was studied, the result .based on the analysis of heterosis, combining ability, the frequency of heterotic hybrid in different type of combinations, indicated clearly that:(l).the crosses between more spikes and large kernel had the highest heterosis over mid-parent, high-parent and the check cultivar on yield per plant among 6 groups. The percents of crosses with strong heterosis average of SCA, and percents of crosses with higher SCA(SCA>1) of this group are also the highest among the 6 groups, it is concluded that the more spikes *large kernel is the parental combination type with strong heterosis.(2).there is common over mid-parent heterosis in Fl agronomic characters among 9 characters on which data was collected. The sequence of characters over mid-parent heterosis is yield per plant>yield per main spike > plant height >100 kernel weight>knob length under main spike >kernel numbers per main spike >Iittle spike per main spike height > numbers of spikes per plant. It is also found that the crosses with strong heterosis in yield should have at least two yield components with better positive heterosis.(3). It was found that GCA had no relationships to SCA, but correlated with heterosis . The correlation coefficients is no significant. The SCA had significant and positive correlation with heterosis.II. Using RAPD marker to classify 16 wheat cultivar, indicated clearly that: (l).the polymorphism of winter wheat was very low, RAPD marked genetic distance(GD) had significant correlation with number of little spikes per main spike over mid-parent heterosis, but had no correlation with yield heterosis. It was indicated that genome difference is not the important factor of yield heterosis.(2).It was found that geography difference was not correlate with the genome difference. Different local cultivar was classified in one group and different lines of the same cultivar was classified in different group, It was indicated that RAPD can be used as a kind of finger mapping in winter wheat.III. the MINIQUE(I) procedures were used for estimating variance components and genetic effect by analyzing 8 parents completely diallel design with Additive-Dominance mode , genotype value and F2 heterosis of F2 generation were then predicted. The result as follows:(1).Significant correlation coefficients between observed and expected genotype values and heterosis for F2 generation indicated that AD model was adaptable in prediction based upon data of parents and F| hybrids.(2). Heterosis over mid-parent value based on population mean was observed in most of the agronomic traits. Heterosis over high-parent value based on population mean was found significant correlation between FI hybrids and its F2 generation. It was indicted that F2 heterosis can be used if FI heterosis was very strong.(3) It was difficult to predict height of F2 generation, but in general circumstance, the relationship between height of F2 generation and difference height of two parents was liner and the equation is Y=4.499+0.184X (R=0.56**) .
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