Results
3.1. Population performance
In the SPS F2 generation, means of each population were similar for each trait and the range within population varied from 6% for uniformity to over 30% for elongation and micronaire. The range
for each trait in SPS compared to the standard errors of control
single plants was five-fold (LP and micronaire)to ten-fold for length
(Table 2) indicating variability existed within the SPS populations.
The effects of year and treatment (population and controls) for
PRs and replicated data were significant for all traits, along with
the year by treatment interaction (Table 2). The ranking of the pop-
ulation means was consistent for each trait across years but the
magnitude was affected by the growing conditions. The year by
treatment interactions were associated with differences between
populations and control cultivars. For example, the control Siokra
24 out yielded the three population means and Sicot 71 in 2012–13,
but had relatively lower yield in the PR 2010–11 season. Both con-
trol cultivars had relatively lower LP compared with populations
in 2010–11 than in other seasons. For fibre properties, there was
a greater difference in fibre length and strength between controls
and population means in 2010–11 than in other years. For micron-
aire, fineness, maturity ratio and YQI, population CSX211 varied in
ranking between 2010–11 and 2012–13. Importantly, populations
had significant diversity between the 100 lines and the interaction
of year by line was significant in yield, LP and length (Table 3),
indicating the ranking of lines within populations differed in some
years for these traits.