Mutation breeding for improved internal quality and appearance in Russet Burbank

Mutation breeding was investigated as a method to improve important quality traits in the cultivar Russet Burbank. Two thousand excised eyes were irradiated with a gamma-ray dose of 35 Gy. The irradiated eye pieces were planted directly to the field and approximately three tubers from each of resulting plants were harvested and, constituted the initial 6000 clone selection population. The M(1)V(1) tubers and subsequent clonal progeny were subjected to six generations of evaluation and selection. Selection criteria included appearance, resistance to blackspot bruise, french fry color following storage at 4 C, and specific gravity. At the end of six selection cycles, five mutants remained from the original population of approximately 6000. These included two mutants selected for improved appearance (RBM161 and RBM366), one for resistance to blackspot bruise (RBM166), one for french fry color (RBM13), and one for specific gravity (RBM170). An analysis of variance over three years showed that the three mutants selected for internal quality traits (RBM13, RBM166, and RBM170) produced lower yields in comparison with two Russet Burbank control clones. RBM161 was selected for its heavier, more uniform russet skin, and appeared to be similar to the mother clone for important agronomic and quality traits. RBM366 was selected for improved appearance, typified by higher breeders preference scores and a lower percentage of tubers exhibiting external defects. It also produced higher total and U.S. No. 1 yields than the controls.