Stratification of sorghum hybrid testing sites in southern Africa based on grain yield

Sequential retrospective (SeqRet) pattern analysis technique was applied to classify sorghum hybrid testing sites in accordance with their similarity for yield differentiation among genotypes. Historical grain yield data from 150 multi-environment trials (METs) conducted at 23 sites in the Southern Africa Development Community (SADC) region during 1987/1988–1992/1993 was used. The sites were clustered into six major environment groups in the SADC region with a model fit of R 2 = 68%. Analysis of these 6 years’ data together with additional data from 1999/2000 stratified the 23 sites in the same six major groups ( R 2 = 69%), the additional five sites in 1999/2000 classified with appropriate site groups. These results suggest that future sorghum hybrid testing could be cost-effectively conducted in a few representative sites selected from within each of the six identified site groups.