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Independent Culling is a selection strategy whereby a genotype is culled if it does not meet the requirement for a single trait, regardless of its levels on other traits. This strategy guarantees that a genotype that is selected as a new cultivar/variety has no major defects.
In the multi-trait selection tool of GGEbiplot, Independent culling on a trait is conducted by considering three pieces of specifications by the researcher:
1. Culling rate (0 to 50%),
2. Weight (relative importance, [-1, +1]) of the trait, and
3. Action direction of the trait (the sign of the weight).
For Example: If the culling rate is 30%, and the weight of the trait is 0.5, then genotypes with a value of 0.15 (= 0.3 * 0.5) or lower relatitve to the maximum value of the trait will be discarded. If the culling rate is 30%, and the weight is -0.6, then genotypes of a value of 0.82 (= 1 - 0.3 * 0.6) or higher relative to the maximum will be discarded.