PERFORMANCE AND STABILITY OF 9 4X CLONES FROM 4X-2X CROSSES AND 4 COMMERCIAL CULTIVARS

Nine clones from 4x-2x crosses were evaluated along with four cultivars in six Wisconsin environments. The 4x clones from 4x-2x crosses had as their 2x parents hybrids with haploid Tuberosum and either Group Phureja or Solanum tarijense. The 2x hybrids produced 2n pollen by first division restitution. The traits evaluated were marketable yield, mass density and chip color. Stability analysis was conducted by determining the linear relationships between mean yield of individual clones and environmental mean yields. Mean square deviations from linear regression (s2d) were used to evaluate phenotypic stability and regression coefficients (b) as environmental response parameters. Three 4x clones from 4x-2x crosses were more stable and not significantly different for yield than cv. Atlantic; some also had superior specific gravity and chip color. The results suggest that the 4x x 2x breeding method is very efficient for the production of high yielding, stable clones with superior processing qualities, particularly since the 4x clones from 4x-2x crosses originated from very small source populations.