A New Method for Identifying Lines with Superior and Stable Alleles to Improve An Elite Single Cross Hybrid.

Choice of the donor line, among the several available lines, to improve an elite single cross hybrid is critical. Theory, based on quantitative genetics, has been developed to identify line (I_w) possessing favorable dominant alleles (µG’) not present in the elite single cross (I₁ X I₂) by Dudley and others. This theory followed by several other modifications proved the effectiveness of these methods in maize and several other crops. However, the stability of these alleles (µG’) when tested under different environments, locations or years or combination of both, may vary when GxE interactions are significant. Even though, in general, combined data over environments is considered for analysis of µG’ there is also a need to take into consideration of the µG’ at each individual environment in order to identify the most effective donor which could possess the significant favorable alleles uniformly under all target environments. To fulfill this objective, a new and simple method has been proposed to select a donor line not only with possessing higher proportion of significant favorable alleles (µG’), but also with the ability in possessing the same degree of higher proportion of significant favorable alleles (µG’) under all environments considered for testing. This method consists of calculating the proportion of significant favorable dominant alleles (µG’) based on the combined data across several environments, besides a non parametric score for each donor. This non parametric score for each donor in each environment has been assigned as fallows. If µG’ is +ve and > than 2 SE, +1; if µG’ is +ve or -ve and < than 2 SE, 0; if µG’ is -ve and > than 2 SE, -1. So if a donor has shown the significant proportion of µG’ in all the environments its maximum score would be N (where, N=No of environments). Therefore, this new procedure will help in selecting the donor with maximum significant favorable alleles (µG’) based on combined data with maximum score which signifies the donor with stable in possessing the same degree of higher proportion of significant favorable dominant alleles (µG’) under all environments considered for testing. This procedure when applied to a known data set clearly showed the change in the ranks of the donors. Field validation of this technique using maize is under progress.