|Ray, D - THE UNIV OF ARIZONA|
|Lorenz, G - ARIZONA STATE UNIV|
Submitted to: American Society of Agronomy
Publication Type: Abstract Only
Publication Acceptance Date: September 29, 2000
Publication Date: N/A
Technical Abstract: Plant breeding in guayule, a rubber and latex producing plant, has not been as effective as predicted or desired. Broad sense heritabilities were estimated for each trait and year by dividing the genotypic by the total variance. To estimate the genetic component of the measured variance for each trait, the environmental effects (variance from clonally propagated plants) were subtracted from the total variance (variance from open-pollinated (OP) seed-propagated plants). The heritability estimates calculated for each trait differed from year-to- year. For instance, heritability for plant height was estimated in line AZ-2 to be 0.84 at one year of age; 0.47 at two years of age; and 0.0 at three years of age. As the plant grows over several seasons, the environmental effects compound, masking the genetic effects, making effective selection choices more difficult. Selections for the measured traits in this study appear to be most effective during the first and second years of growth, with effectiveness diminishing during the third year. Most selections previous to this study were performed between three and five years of growth, thus suggesting one reason for the lack of significant progress in most breeding programs.