Identification of best testers for heterotic grouping of tropical maize inbred lines using GGE biplot

An understanding of the heterotic pattern in the active germplasm is the first and crucial step in any hybrid breeding program. Diallel and line x tester (L x T) mating designs were extensively followed to understand the heterotic pattern based on the combining ability information. The present study adopted GGE biplots, generated using the L x T matrix to understand the tropical maize germplasm's heterotic pattern and identify the best tester combinations for heterotic grouping. The L x T matrix and combining ability information was generated by evaluating 985 testcross, generated by crossing 110 diverse tropical inbred lines with 10 inbred testers at two geographically diverse locations. The stability of combining ability effects, the magnitude and direction of combining ability effects, and also the discrimination and representativeness of testers were considered for the identification of best tester combinations for heterotic grouping. The present investigation has shown the usefulness of GGE biplots' effectiveness in understanding the heterotic pattern and identifying the best tester combinations for heterotic grouping. The results of the present investigation revealed the existing heterotic pattern in the elite tropical maize inbred lines that were extensively used in hybrid maize breeding. The findings of the present study are of immense practical significance, which not only guides different hybrid maize breeding programs but also helps to identify the best testers in their respective hybrid breeding programs. The study showed that the GGE biplot method can be adopted to understand the active germplasm's heterotic pattern and organize the germplasm into different heterotic groups.