We have highlighted that Acala cultivars have been general outliers with lower than average yield for their length and particularly strength values in US and AUS data sets (Fig. 1 and Fig. 2).
Acala cotton has been developed in western US with particular attention to fibre properties and Verticillium Wilt (Verticillium dahliae) resistance and for some period under a one cultivar law in CA ( Smith et al., 1999).
As a result they tend to be lower yielding in regions outside of their origin ( Zhang et al., 2005).
Thus Acala cultivars may have been penalised by using overall mean yield across sites in US data.
This was particularly the case from 1999 to 2004 with few sites in western US.
In 2005–2009,
the research added Las Cruces, NM, improving the relative performance of Acala types ( USDA, 2011).